Publications by category
Journal articles
Witt M, Godley B, Pikesley S (In Press). A novel approach to estimate the distribution, density and at-sea risks of a
centrally-placed mobile marine vertebrate. Biological Conservation
Varela MR, Patricio AR, Anderson K, Broderick AC, DeBell L, Hawkes LA, Tilley D, Snape R, Westoby MJ, Godley BJ, et al (In Press). Assessing climate change associated sea level rise impacts on sea turtle nesting beaches using drones, photogrammetry and a novel GPS system. Global Change Biology
Duncan E, Arrowsmith JA, Bain CE, Bowdery H, Broderick A, Chalmers T, Fuller WJ, Galloway T, Lee JH, Lindeque PK, et al (In Press). Diet-related selectivity of macroplastic ingestion in green turtles (Chelonia mydas) in the eastern Mediterranean. Scientific Reports
Weber SB, Richardson AJ, Brown J, Bolton M, Clark B, Godley B, Leat EHK, Oppel S, Soetaert KER, Weber N, et al (In Press). Direct evidence of a prey depletion ‘halo’ surrounding a pelagic predator colony. Proceedings of the National Academy of Sciences of USA
Patricio AR, Formia A, Barbosa C, Broderick AC, Bruford M, Carreras C, Catry P, Ciofi C, Regalla A, Godley BJ, et al (In Press). Dispersal of green turtles from Africa’s largest rookery assessed through genetic markers. Marine Ecology Progress Series
Bjorndal KA, Bolten AB, Chaloupka M, Saba VS, Bellini C, Marcovaldi MAG, Santos AJ, Bortolon LFW, Meylan AB, Meylan PA, et al (In Press). Ecological regime shift drives declining growth rates of sea turtles throughout the West Atlantic. Global Change Biology
Rees AF, Carreras C, Broderick AC, Margaritoulis D, Stringell T, Godley BJ (In Press). Linking loggerhead locations: using multiple methods to determine the origin of sea turtles in feeding grounds. Marine Biology
Stevens M, Broderick AC, Godley BJ, Lown AE, Troscianko J, Weber N, Weber SB (In Press). Phenotype-Environment Matching in Sand Fleas. Biology Letters
Stringell TB, Clerveaux WV, Godley BJ, Phillips Q, Ranger S, Richardson PB, Sanghera A, Broderick AC (In Press). Protecting the breeders: research informs legislative change in a marine turtle fishery.
Biodiversity and ConservationAbstract:
Protecting the breeders: research informs legislative change in a marine turtle fishery
Marine turtles are sensitive to harvesting because of life-cycle traits such as longevity, late maturity and natal philopatry. The take of nesting females is of conservation concern because they are key to population maintenance and has led to global efforts to protect this life stage. In the Turks and Caicos Islands (TCI; a UK Overseas Territory in the Caribbean), previous turtle fishery legislation protected nesting turtles on the beach but not in the water, where turtles over a minimum size were subject to legal take. In a 2-year study, we undertook nesting beach and in-water surveys, molecular analyses, satellite tracking and collation of fisheries landing data to investigate the populations of green
(Chelonia mydas) and hawksbill (Eretmochelys imbricata) turtles in the TCI and its turtle fishery. Adults were frequently taken in one of the region’s largest legal and artisanal turtle fisheries. We suggest that nesting populations in the TCI, which contain genetically unique
haplotypes, have diminished since the 1980s, likely as a result of the harvest of adults. Using these multiple lines of evidence, we highlight the inadequacies of the former fishery regulations and propose specific legislative amendments, which, as a result of this study, were implemented on 1 July 2014 by the TCI government. With good enforcement, these measures will protect adults breeding in the TCI and those from nesting rookeries in the region that use the waters of the TCI, improve the management of this fishery, and safeguard fisher livelihoods.
Abstract.
Palmer JL, Armstrong C, Akbora HD, Beton D, Çağlar Ç, Godley BJ, Metcalfe K, Özkan M, Snape RTE, Broderick AC, et al (2024). Behavioural patterns, spatial utilisation and landings composition of a small-scale fishery in the eastern Mediterranean.
Fisheries Research,
269Abstract:
Behavioural patterns, spatial utilisation and landings composition of a small-scale fishery in the eastern Mediterranean
Small-scale fisheries (SSFs) are crucial for global food security and cultural heritage, however, information on their spatial distribution and practices are often lacking, precluding effective management and mitigation of ecological impacts. This is acutely the case in the eastern Mediterranean basin, where, despite concerns being raised regarding the magnitude of marine turtle bycatch in SSFs over two decades ago, a poor understanding of the fishery persists. To address this knowledge gap, we characterised the SSF fleet of Northern Cyprus through a combination of onboard observations, fisher self-reporting and vessel tracking to provide the first comprehensive overview of the fishery. Northern Cyprus had a fleet size, standardised by coastline length, ranked 14th of 23 Mediterranean fleets assessed, with an estimated 49542 and 57198 fishing days in total in 2020 and 2021, respectively. Vessels operated mainly over the continental shelf (< 200 m) and were predominantly active during the night (53.2%, n = 573378 locations). Clear crepuscular peaks in vessel activity and gear deployment raise concerns over spatiotemporal overlap with vulnerable species, even within MPAs previously established to protect them. Fishers (n = 1296 fishing operations) predominantly utilised static and demersal gear types including gill nets (35.0%), trammel nets (27.3%), trammel and gill nets combined (20.3%), demersal longlines (17.0%) and handlines (0.5%). Landings composition was highly diverse with a minimum of 238 different taxa identified, including, but not limited to, 123 species of bony fish, 22 elasmobranch species, 3 marine turtle species and 12 mollusc species of which 18.6% are considered threatened either at a Mediterranean or global scale. However, over 70.0% of total landing mass was comprised of only five species including bogue (Boops boops), picarel (Spicara smaris), blotched picarel (Spicara maena), greater amberjack (Seriola dumerili) and Mediterranean parrotfish (Sparisoma cretense). As the most up to date and detailed understanding of this fishery's operating behaviours, our research compares the results obtained from onboard observer and self-reporting fisher sampling methodologies and discusses the caveats of each and identifies potential opportunities to adapt existing practices and MPAs to improve long-term sustainability of the fishery, whilst maintaining its socio-economic benefits to the local community.
Abstract.
Fuentes MMPB, Santos AJB, Abreu-Grobois A, Briseño-Dueñas R, Al-Khayat J, Hamza S, Saliba S, Anderson D, Rusenko KW, Mitchell NJ, et al (2023). Adaptation of sea turtles to climate warming: Will phenological responses be sufficient to counteract changes in reproductive output?.
Glob Chang BiolAbstract:
Adaptation of sea turtles to climate warming: Will phenological responses be sufficient to counteract changes in reproductive output?
Sea turtles are vulnerable to climate change since their reproductive output is influenced by incubating temperatures, with warmer temperatures causing lower hatching success and increased feminization of embryos. Their ability to cope with projected increases in ambient temperatures will depend on their capacity to adapt to shifts in climatic regimes. Here, we assessed the extent to which phenological shifts could mitigate impacts from increases in ambient temperatures (from 1.5 to 3°C in air temperatures and from 1.4 to 2.3°C in sea surface temperatures by 2100 at our sites) on four species of sea turtles, under a "middle of the road" scenario (SSP2-4.5). Sand temperatures at sea turtle nesting sites are projected to increase from 0.58 to 4.17°C by 2100 and expected shifts in nesting of 26-43 days earlier will not be sufficient to maintain current incubation temperatures at 7 (29%) of our sites, hatching success rates at 10 (42%) of our sites, with current trends in hatchling sex ratio being able to be maintained at half of the sites. We also calculated the phenological shifts that would be required (both backward for an earlier shift in nesting and forward for a later shift) to keep up with present-day incubation temperatures, hatching success rates, and sex ratios. The required shifts backward in nesting for incubation temperatures ranged from -20 to -191 days, whereas the required shifts forward ranged from +54 to +180 days. However, for half of the sites, no matter the shift the median incubation temperature will always be warmer than the 75th percentile of current ranges. Given that phenological shifts will not be able to ameliorate predicted changes in temperature, hatching success and sex ratio at most sites, turtles may need to use other adaptive responses and/or there is the need to enhance sea turtle resilience to climate warming.
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O’Keefe M, Bengil EGT, Palmer JL, Beton D, Çağlar Ç, Godley BJ, Özkan M, Snape RTE, Broderick AC (2023). Diversity and distribution of elasmobranchs in the coastal waters of Cyprus: using bycatch data to inform management and conservation. Frontiers in Marine Science, 10
Kaska A, Koç G, Sözbilen D, Salih D, Glidan A, Elsowayeb AA, Saied A, Margaritoulis D, Theodorou P, Rees A, et al (2023). Increased sample size provides novel insights into population structure of Mediterranean loggerhead sea turtles. Conservation Genetics Resources, 15(1-2), 67-75.
Mazaris AD, Dimitriadis C, Papazekou M, Schofield G, Doxa A, Chatzimentor A, Turkozan O, Katsanevakis S, Lioliou A, Abalo-Morla S, et al (2023). Priorities for Mediterranean marine turtle conservation and management in the face of climate change.
J Environ Manage,
339Abstract:
Priorities for Mediterranean marine turtle conservation and management in the face of climate change.
As climate-related impacts threaten marine biodiversity globally, it is important to adjust conservation efforts to mitigate the effects of climate change. Translating scientific knowledge into practical management, however, is often complicated due to resource, economic and policy constraints, generating a knowledge-action gap. To develop potential solutions for marine turtle conservation, we explored the perceptions of key actors across 18 countries in the Mediterranean. These actors evaluated their perceived relative importance of 19 adaptation and mitigation measures that could safeguard marine turtles from climate change. of importance, despite differences in expertise, experience and focal country, the perceptions of researchers and management practitioners largely converged with respect to prioritizing adaptation and mitigation measures. Climate change was considered to have the greatest impacts on offspring sex ratios and suitable nesting sites. The most viable adaptation/mitigation measures were considered to be reducing other pressures that act in parallel to climate change. Ecological effectiveness represented a key determinant for implementing proposed measures, followed by practical applicability, financial cost, and societal cost. This convergence in opinions across actors likely reflects long-standing initiatives in the Mediterranean region towards supporting knowledge exchange in marine turtle conservation. Our results provide important guidance on how to prioritize measures that incorporate climate change in decision-making processes related to the current and future management and protection of marine turtles at the ocean-basin scale, and could be used to guide decisions in other regions globally. Importantly, this study demonstrates a successful example of how interactive processes can be used to fill the knowledge-action gap between research and management.
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de Kock W, Mackie M, Ramsøe M, Allentoft ME, Broderick AC, Haywood JC, Godley BJ, Snape RTE, Bradshaw PJ, Genz H, et al (2023). Threatened North African seagrass meadows have supported green turtle populations for millennia.
Proceedings of the National Academy of Sciences,
120(30).
Abstract:
Threatened North African seagrass meadows have supported green turtle populations for millennia
. “Protect and restore ecosystems and biodiversity”
. is the second official aim of the current UN Ocean Decade (2021 to 2030) calling for the identification and protection of critical marine habitats. However, data to inform policy are often lacking altogether or confined to recent times, preventing the establishment of long-term baselines. The unique insights gained from combining bioarchaeology (palaeoproteomics, stable isotope analysis) with contemporary data (from satellite tracking) identified habitats which sea turtles have been using in the Eastern Mediterranean over five millennia. Specifically, our analysis of archaeological green turtle (
. Chelonia mydas
. ) bones revealed that they likely foraged on the same North African seagrass meadows as their modern-day counterparts. Here, millennia-long foraging habitat fidelity has been directly demonstrated, highlighting the significance (and long-term dividends) of protecting these critical coastal habitats that are especially vulnerable to global warming. We highlight the potential for historical ecology to inform policy in safeguarding critical marine habitats.
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Collins C, Letessier TB, Benaragama A, Broderick A, Wijesundara I, Wijetunge D, Nuno A (2023). Valuable bycatch: Eliciting social importance of sharks in Sri Lanka through value chain analysis.
Marine Policy,
157Abstract:
Valuable bycatch: Eliciting social importance of sharks in Sri Lanka through value chain analysis
Decades of unsustainable fishing have caused widespread declines in shark populations leading to calls for increased management and policy. To design successful measures, an understanding of the social context and drivers for trade is needed. This study uses a value chain approach in Sri Lanka, where shark landings have declined rapidly, to map shark trade actors, ascertain determinants of price of shark meat and determine wider social value of shark products. Data was collected over one year from surveys of sales events (n = 630), and semi-structured interviews (n = 24), at two sites on the south and west coasts. We identify a dynamic, flexible supply chain with a small number of specialised stakeholders that may alternate roles depending on factors such as supply of sharks. Sharks were the primary income source for most (71%, n = 17) and 25% (n = 6) reported no alternative income sources. Trade was dominated by dried shark meat in the domestic market, and demand shaped by its perceived nutritional benefits and taste. Identification of species was difficult, and shark meat was primarily sold as size categories, however, whether or not shark was sold as blue shark (Prionace glauca) significantly impacted price reportedly due to lower international demand for their fins. Stakeholders perceived substantial drops in shark landings and trade > 10 years ago. We show that, within Sri Lanka, shark products represent a nexus of two dramatically different markets: high-value fins for their export markets and low to medium-value meat important for domestic earnings. The presence of dried products reportedly increases resilience of shark trade to socio-ecological shocks. Disentangling the relative social importance of these products, through product-specific and species-specific data is vital for a move towards predictive management that is capable of robust outcomes.
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DiMatteo A, Cañadas A, Roberts J, Sparks L, Panigada S, Boisseau O, Moscrop A, Fortuna CM, Lauriano G, Holcer D, et al (2022). Basin-wide estimates of loggerhead turtle abundance in the Mediterranean Sea derived from line transect surveys. Frontiers in Marine Science, 9
Al Ameri H, Al Harthi S, Al Kiyumi A, Al Sariri T, Al-Zaidan A, Antonopoulou M, Broderick A, Chatting M, Das H, Hesni M, et al (2022). Biology and conservation of marine turtles in the northwestern Indian Ocean: a review. Endangered Species Research, 48, 67-86.
Al Ameri H, Al Harthi S, Al Kiyumi A, Al Sariri T, Al-Zaidan A, Antonopoulou M, Broderick A, Chatting M, Das H, Hesni M, et al (2022). CORRIGENDUM: Biology and conservation of marine turtles in the northwestern Indian Ocean: a review. Endangered Species Research, 48
de Geer C, Bourjea J, Broderick A, Dalleau M, Fernandes R, Harris L, Inteca G, Kiponda F, Louro C, Mortimer J, et al (2022). Marine turtles of the African east coast: current knowledge and priorities for conservation and research. Endangered Species Research, 47, 297-331.
Snape RTE, Beton D, Davey S, Godley BJ, Haywood J, Omeyer LCM, Ozkan M, Broderick AC (2022). Mediterranean green turtle population recovery increasingly depends on Lake Bardawil, Egypt.
Global Ecology and Conservation,
40Abstract:
Mediterranean green turtle population recovery increasingly depends on Lake Bardawil, Egypt
To assign conservation status to a population, its size, trends, and distribution must be estimated. The Mediterranean green turtle population has shown signs of recovering over the past decade, likely in response to nest protection, but satellite tracking suggests adult foraging remains largely restricted to only a few key sites in the eastern Mediterranean. Previous research suggested that the majority of green turtles nesting at an important rookery in Cyprus, forage in Lake Bardawil, Egypt making an observed population increase dependent on this important site, which is under a high degree of anthropogenic maintenance. Here we provide new data that further demonstrates the importance of Lake Bardawil to green turtles that nest at other major rookeries on Cyprus, in the Karpaz Peninsula, with 74 % of satellite tracked females (n = 19) migrating to this key site. We also report on the first systematic nest counts for this area in over two decades and identify the inter-nesting habitat used by females nesting at these important beaches on the north and south coasts of the Peninsula. Comparing the oldest available 3-year nest count averages (1993–1995), with nest counts undertaken as part of this study (2017–2019), mean annual nest numbers increased from 186 to 554, an increase of 198 %. Our data confirm the continued importance of these beaches for the Mediterranean green turtle population and underscore the reliance of this endangered population on a man-made lagoon for recent increases in clutch counts at monitored beaches. The results highlight the utility of satellite telemetry to inform conservation status assessments and establishing conservation at both nesting and foraging sites across the population.
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Kot CY, Åkesson S, Alfaro‐Shigueto J, Amorocho Llanos DF, Antonopoulou M, Balazs GH, Baverstock WR, Blumenthal JM, Broderick AC, Bruno I, et al (2022). Network analysis of sea turtle movements and connectivity: a tool for conservation prioritization.
Diversity and Distributions,
28(4), 810-829.
Abstract:
Network analysis of sea turtle movements and connectivity: a tool for conservation prioritization
AbstractAimUnderstanding the spatial ecology of animal movements is a critical element in conserving long‐lived, highly mobile marine species. Analyzing networks developed from movements of six sea turtle species reveals marine connectivity and can help prioritize conservation efforts.LocationGlobal.MethodsWe collated telemetry data from 1235 individuals and reviewed the literature to determine our dataset's representativeness. We used the telemetry data to develop spatial networks at different scales to examine areas, connections, and their geographic arrangement. We used graph theory metrics to compare networks across regions and species and to identify the role of important areas and connections.ResultsRelevant literature and citations for data used in this study had very little overlap. Network analysis showed that sampling effort influenced network structure, and the arrangement of areas and connections for most networks was complex. However, important areas and connections identified by graph theory metrics can be different than areas of high data density. For the global network, marine regions in the Mediterranean had high closeness, while links with high betweenness among marine regions in the South Atlantic were critical for maintaining connectivity. Comparisons among species‐specific networks showed that functional connectivity was related to movement ecology, resulting in networks composed of different areas and links.Main conclusionsNetwork analysis identified the structure and functional connectivity of the sea turtles in our sample at multiple scales. These network characteristics could help guide the coordination of management strategies for wide‐ranging animals throughout their geographic extent. Most networks had complex structures that can contribute to greater robustness but may be more difficult to manage changes when compared to simpler forms. Area‐based conservation measures would benefit sea turtle populations when directed toward areas with high closeness dominating network function. Promoting seascape connectivity of links with high betweenness would decrease network vulnerability.
Abstract.
Wu NC, Rusli MU, Broderick AC, Barneche DR (2022). Size scaling of sea turtle reproduction may reconcile fundamental ecology and conservation strategies at the global scale.
Global Ecology and Biogeography,
31(7), 1277-1289.
Abstract:
Size scaling of sea turtle reproduction may reconcile fundamental ecology and conservation strategies at the global scale
Aim: the body size of marine megafauna can influence population dynamics because larger females have disproportionally greater reproductive output. We explored how this size scaling relationship can affect predictions of population size structure in nesting sea turtles by combining a phylogenetically controlled meta-analysis with a long-term field nesting survey. Location: Global (meta-analysis) and Malaysia (field survey). Time period: Present. Major taxa studied: Sea turtles. Methods: We extracted body size and reproductive parameters of all sea turtle species from the literature and estimated the reproductive-energy output using allometric models. We then examined the relationship between body size and the proportion of protected nesting beaches by country as an indicator of conservation efforts on body size. Long-term monitoring (1993–2019) of body size and nesting data on green turtles (Chelonia mydas) from Redang Island (Malaysia) was used to examine temporal changes in body size and fecundity and to test whether the size scaling of fecundity was isometric (linear) or allometric (curvilinear). Results: We show that the total reproductive-energy output of larger nesting females was, on average, disproportionately greater in all sea turtle species. We found no strong correlations for countries with a higher proportion of protected nesting sites with female size. Finally, we showed that scaling-derived calculations of population-level yearly reproductive output in the green turtle population from Redang Island were more accurate when using a hyperallometric (rather than an isometric) relationship at the individual level. Main conclusions: Understanding ecosystem function and conservation effort requires accurate predictions of population trends. Our findings highlight the necessity to account for scaling effects of body size in predicting anthropogenically mediated population shifts, and the need to protect large females in order to facilitate effective population replenishment.
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Gough C, Ateweberhan M, Godley BJ, Harris A, Le Manach F, Zafindranosy E, Broderick AC (2022). Temporal Change and Fishing Down Food Webs in Small-Scale Fisheries in Morondava, Madagascar. Frontiers in Marine Science, 9
Barbanti A, Blumenthal JM, Broderick AC, Godley BJ, Prat-Varela A, Turmo M, Pascual M, Carreras C (2022). The architecture of assisted colonisation in sea turtles: building new populations in a biodiversity crisis.
Nat Commun,
13(1).
Abstract:
The architecture of assisted colonisation in sea turtles: building new populations in a biodiversity crisis.
Due to changing environmental conditions, many species will have to migrate or occupy new suitable areas to avoid potential extinction in the current biodiversity crisis. Long-lived animals are especially vulnerable and ex-situ conservation actions can provide solutions through assisted colonisations. However, there is little empirical evidence on the process of founding new populations for such species or the feasibility of assisted colonisations as a viable conservation measure. Here, we combined genetics with reproductive data to study the rise of two wild populations of green turtles (Chelonia mydas) in the Cayman Islands as a possible outcome of a reintroduction program started 50 years ago. We show that both populations are highly related to the captive population but rapidly diverged due to genetic drift. Individuals from the reintroduced populations showed high levels of nest fidelity, within and across nesting seasons, indicating that philopatry may help reinforce the success of new populations. Additionally, we show that reintroduction from captive populations has not undermined the reproductive fitness of first generation individuals. Sea turtle reintroduction programs can, therefore, establish new populations but require scientific evaluation of costs and benefits and should be monitored over time to ensure viability in the long-term.
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Blumenthal JM, Hardwick JL, Austin TJ, Broderick AC, Chin P, Collyer L, Ebanks-Petrie G, Grant L, Lamb LD, Olynik J, et al (2021). Cayman Islands Sea Turtle Nesting Population Increases over 22 Years of Monitoring.
Frontiers in Marine Science,
8Abstract:
Cayman Islands Sea Turtle Nesting Population Increases over 22 Years of Monitoring
Given differing trajectories of sea turtle populations worldwide, there is a need to assess and report long-term population trends and determine which conservation strategies are effective. In this study, we report on sea turtle nest monitoring in the Cayman Islands over a 22-year period. We found that green (Chelonia mydas) and loggerhead (Caretta caretta) nest numbers increased significantly across the three islands since monitoring began in 1998, but that hawksbill nest numbers remained low with a maximum of 13 nests recorded in a season. Comparing the first 5 years of nest numbers to the most recent 5 years, the greatest percentage increase in green turtle nests was in Grand Cayman from 82 to 1,005 nests (1,126%), whereas the greatest percentage increase for loggerhead turtle nests was in Little Cayman from 10 to 290 nests (3,800%). A captive breeding operation contributed to the increase in the Grand Cayman green turtle population, however, loggerhead turtles were never captive-bred, and these populations began to increase after a legal traditional turtle fishery became inactive in 2008. Although both species have shown significant signs of recovery, populations remain at a fragment of their historical level and are vulnerable to threats. Illegal harvesting occurs to this day, with multiple females taken from nesting beaches each year. For nests and hatchlings, threats include artificial lighting on nesting beaches, causing hatchlings to misorient away from the sea, and inundation of nests by seawater reducing hatch success. The impacts of lighting were found to increase over the monitoring period. Spatial data on nest distribution was used to identify critical nesting habitat for green and loggerhead turtles and is used by the Cayman Islands Department of Environment to facilitate remediation of threats related to beachside development and for targeted future management efforts.
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Palmer JL, Beton D, Çiçek BA, Davey S, Duncan EM, Fuller WJ, Godley BJ, Haywood JC, Hüseyinoğlu MF, Omeyer LCM, et al (2021). Dietary analysis of two sympatric marine turtle species in the eastern Mediterranean.
Marine Biology,
168(6).
Abstract:
Dietary analysis of two sympatric marine turtle species in the eastern Mediterranean
AbstractDietary studies provide key insights into threats and changes within ecosystems and subsequent impacts on focal species. Diet is particularly challenging to study within marine environments and therefore is often poorly understood. Here, we examined the diet of stranded and bycaught loggerhead (Caretta caretta) and green turtles (Chelonia mydas) in North Cyprus (35.33° N, 33.47° E) between 2011 and 2019. A total of 129 taxa were recorded in the diet of loggerhead turtles (n = 45), which were predominantly carnivorous (on average 72.1% of dietary biomass), foraging on a large variety of invertebrates, macroalgae, seagrasses and bony fish in low frequencies. Despite this opportunistic foraging strategy, one species was particularly dominant, the sponge Chondrosia reniformis (21.5%). Consumption of this sponge decreased with increasing turtle size. A greater degree of herbivory was found in green turtles (n = 40) which predominantly consumed seagrasses and macroalgae (88.8%) with a total of 101 taxa recorded. The most dominant species was a Lessepsian invasive seagrass, Halophila stipulacea (31.1%). This is the highest percentage recorded for this species in green turtle diet in the Mediterranean thus far. With increasing turtle size, the percentage of seagrass consumed increased with a concomitant decrease in macroalgae. Seagrass was consumed year-round. Omnivory occurred in all green turtle size classes but reduced in larger turtles (> 75 cm CCL) suggesting a slow ontogenetic dietary shift. Macroplastic ingestion was more common in green (31.6% of individuals) than loggerhead turtles (5.7%). This study provides the most complete dietary list for marine turtles in the eastern Mediterranean.
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Omeyer LCM, Stokes KL, Beton D, Çiçek BA, Davey S, Fuller WJ, Godley BJ, Sherley RB, Snape RTE, Broderick AC, et al (2021). Investigating differences in population recovery rates of two sympatrically nesting sea turtle species.
Animal Conservation,
24(5), 832-846.
Abstract:
Investigating differences in population recovery rates of two sympatrically nesting sea turtle species
AbstractEstimating life‐history traits and understanding their variation underpins the management of long‐lived, migratory animals, while knowledge of recovery dynamics can inform the management of conservation‐dependent species. Using a combination of nest counts and individual‐based life‐history data collected since 1993, we explore the drivers underlying contrasting population recovery rates of sympatrically nesting loggerhead (Caretta caretta) and green (Chelonia mydas) turtles in North Cyprus. We found that nest counts of loggerhead and green turtles from 28 beaches across the island increased by 46% and 162%, respectively over the past 27 years. A Bayesian state‐space model revealed that, at our individual‐based monitoring site, nesting of green turtles increased annually at four times the rate of that of loggerhead turtles. Furthermore, we found that loggerhead turtles nesting at the individual‐based monitoring site had stable reproductive parameters and average adult survival for the species and are the smallest breeding adults globally. Based on results from multiple matrix model scenarios, we propose that higher mortality rates of individuals in all age classes (likely driven by differences in life history and interaction with fisheries), rather than low reproductive output, are impeding the recovery of this species. While the increase in green turtles is encouraging, the Mediterranean population is estimated to have around 3,400 adults and is restricted to the Eastern Basin. The recovery of loggerhead turtles is likely to be compromised until mortality rates in the region are adequately quantified and mitigated. As survival of immature individuals is a powerful driver for sea turtle population numbers, additional efforts should target management at pelagic and neritic foraging areas. Understanding threats faced by immature life stages is crucial to accurately parameterise population models and to target conservation actions for long‐lived marine vertebrates.
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Beton D, Broderick AC, Godley BJ, Kolaç E, Ok M, Snape RTE (2021). New monitoring confirms regular breeding of the Mediterranean monk seal in Northern Cyprus.
ORYX,
55(4), 522-525.
Abstract:
New monitoring confirms regular breeding of the Mediterranean monk seal in Northern Cyprus
The Endangered Mediterranean monk seal Monachus monachus is one of the most threatened marine mammals. Across Cyprus, suitable habitat and presence of monk seals is well documented and, recently, camera-trap surveys in Southern Cyprus found there to be pupping. We present results of the first camera-trap surveys in Northern Cyprus spanning the pupping period. Four adult/subadults and three pups were identified in three of eight caves monitored with camera traps. One site on the north-west of the island supported at least three adult/subadult seals and pupping occurred there in 3 consecutive years. The breeding and resting sites identified require urgent conservation to manage threats of disturbance, coastal development and fisheries bycatch. To determine the size of this population, a long-term survey with greater and more continuous coverage is required.
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Collins C, Nuno A, Benaragama A, Broderick A, Wijesundara I, Wijetunge D, Letessier TB (2021). Ocean-scale footprint of a highly mobile fishing fleet: Social-ecological drivers of fleet behaviour and evidence of illegal fishing.
People and Nature,
3(3), 740-755.
Abstract:
Ocean-scale footprint of a highly mobile fishing fleet: Social-ecological drivers of fleet behaviour and evidence of illegal fishing
Managing the footprint of highly mobile fishing fleets is increasingly important due to continuing declines in fish populations. However, social-ecological drivers for fisher behaviour remain poorly understood for many fleets globally. Using the Sri Lankan fleet as a case study, we explored the role of social, environmental and policy drivers of effort distribution and illegal fishing. We used semi-structured interviews and participatory mapping with 95 fishers, combined with explanatory modelling (GLM) and multivariate statistics, including principal component analysis (PCA). Our findings highlighted the broad footprint (~3,800,000 km2) of this fleet, with fishing effort expended in high seas (53.9%), domestic (40.9%) and, illegally, in foreign waters (5.2%). Twenty-six per cent of fishers directly admitted to fishing illegally in foreign waters during interviews, whereas 62% of fishers indicated doing so during participatory mapping. GLMs explained underlying decisions of where to fish (36% of the total deviance in effort distribution) as a function of social variables (14%), notably distance from landing sites (13%), and environmental variables (11%), notably sea surface temperature (10%). Multivariate analysis revealed that individual fisher characteristics associated with illegal fishing, such as a level of reliance on sharks, vary across the fleet. The analysis of qualitative data suggested that the influence of interpersonal and community social networks and perceptions of higher catch value, particularly of sharks, may be important. Our approach demonstrated the utility of mixed methods research, including the collection of qualitative data, for creating a detailed understanding of spatial behaviour, including decisions of whether to fish illegally. Results highlighted the importance of adopting a social-ecological lens to investigate drivers for human behaviour and non-compliance with rules. We advocate for a nuanced approach to monitoring and managing of fleets, including investigating localised social drivers for illegal fishing and enhancing regional transparency in fleet monitoring. A free Plain Language Summary can be found within the Supporting Information of this article.
Abstract.
Nuno A, Matos L, Metcalfe K, Godley BJ, Broderick AC (2021). Perceived influence over marine conservation: Determinants and implications of empowerment.
Conservation Letters,
14(3).
Abstract:
Perceived influence over marine conservation: Determinants and implications of empowerment
Understanding empowerment is integral to facilitating sustainable use policies and requires assessing potential drivers. However, critical applications are rare in conservation. Using the island of Príncipe (São Tomé and Príncipe) as a case study, we undertook household surveys (N = 869) to assess potential drivers of psychological empowerment towards conservation, measured as the perceived abilities of people to individually or collectively influence marine conservation outcomes, accounting for gender. Law enforcement, collective influence, freedom of choice and action, environmental condition and living in coastal community were key variables for understanding perceived personal influence. In particular, no-fishing areas and raising awareness about sustainable practices were recommended by those with higher self-perceived influence. Such information on target groups and factors to promote is essential for facilitating empowerment towards conservation and laying robust foundations for resource comanagement, especially given the role communities can play in the face of limited state capacity and enforcement.
Abstract.
Duncan EM, Broderick AC, Critchell K, Galloway TS, Hamann M, Limpus CJ, Lindeque PK, Santillo D, Tucker AD, Whiting S, et al (2021). Plastic Pollution and Small Juvenile Marine Turtles: a Potential Evolutionary Trap.
FRONTIERS IN MARINE SCIENCE,
8 Author URL.
Collins C, Nuno A, Broderick A (2021). Understanding Persistent Non-compliance in a Remote, Large-Scale Marine Protected Area. Frontiers in Marine Science
Colman LP, Lara PH, Bennie J, Broderick AC, de Freitas JR, Marcondes A, Witt MJ, Godley BJ (2020). Assessing coastal artificial light and potential exposure of wildlife at a national scale: the case of marine turtles in Brazil.
Biodiversity and Conservation,
29(4), 1135-1152.
Abstract:
Assessing coastal artificial light and potential exposure of wildlife at a national scale: the case of marine turtles in Brazil
AbstractCoastal areas provide critical nesting habitat for marine turtles. Understanding how artificial light might impact populations is key to guide management strategies. Here we assess the extent to which nesting populations of four marine turtle species—leatherback (Dermochelys coriacea), olive ridley (Lepidochelys olivacea), hawksbill (Eretmochelys imbricata) and two subpopulations of loggerhead (Caretta caretta) turtles—are exposed to light pollution across 604 km of the Brazilian coast. We used yearly night-time satellite images from two 5-year periods (1992–1996 and 2008–2012) from the US Air Force Defense Meteorological Satellite Programme (DMSP) to determine the proportion of nesting areas that are exposed to detectable levels of artificial light and identify how this has changed over time. Over the monitored time-frame, 63.7% of the nesting beaches experienced an increase in night light levels. Based on nest densities, we identified 54 reproductive hotspots: 62.9% were located in areas potentially exposed to light pollution. Light levels appeared to have a significant effect on nest densities of hawksbills and the northern loggerhead turtle stock, however high nest densities were also seen in lit areas. The status of all species/subpopulations has improved across the time period despite increased light levels. These findings suggest that (1) nest site selection is likely primarily determined by variables other than light and (2) conservation strategies in Brazil appear to have been successful in contributing to reducing impacts on nesting beaches. There is, however, the possibility that light also affects hatchlings in coastal waters, and impacts on population recruitment may take longer to fully manifest in nesting numbers. Recommendations are made to further this work to provide deeper insights into the impacts of anthropogenic light on marine turtles.
Abstract.
Gough CLA, Dewar KM, Godley BJ, Zafindranosy E, Broderick AC (2020). Evidence of Overfishing in Small-Scale Fisheries in Madagascar. Frontiers in Marine Science, 7
Haywood JC, Casale P, Freggi D, Fuller WJ, Godley BJ, Lazar B, Margaritoulis D, Rees AF, Shutler JD, Snape RT, et al (2020). Foraging ecology of Mediterranean juvenile loggerhead turtles: insights from C and N stable isotope ratios.
Marine Biology,
167(3).
Abstract:
Foraging ecology of Mediterranean juvenile loggerhead turtles: insights from C and N stable isotope ratios
AbstractBycatch is one of the key threats to juvenile marine turtles in the Mediterranean Sea. As fishing methods are regional or habitat specific, the susceptibility of marine turtles may differ according to inter- and intra-population variations in foraging ecology. An understanding of these variations is necessary to assess bycatch susceptibility and to implement region-specific management. To determine if foraging ecology differs with region, sex, and size of juvenile loggerhead turtles (Caretta caretta), stable isotope analysis of carbon and nitrogen was performed on 171 juveniles from a range of foraging regions across the central and eastern Mediterranean Sea. Isotope ratios differed with geographical region, likely due to baseline variations in δ13C and δ15N values. The absence of sex-specific differences suggests that within an area, all comparably sized animals likely exploit similar foraging strategies, and therefore, their susceptibility to fisheries threats will likely be similar. The isotope ratios of juveniles occupying the North East Adriatic and North Levantine basin increased with size, potentially due to increased consumption of more prey items at higher trophic levels from a more neritic source. Isotope ratios of juveniles with access to both neritic and oceanic habitats did not differ with size which is consistent with them consuming prey items from both habitats interchangeably. With foraging habitats exploited differently among size classes in a population, the susceptibility to fisheries interactions will likely differ with size; therefore, region-specific management approaches will be needed.
Abstract.
Godley BJ, Broderick AC, Colman LP, Formia A, Godfrey MH, Hamann M, Nuno A, Omeyer LCM, Patrício AR, Phillott AD, et al (2020). Reflections on sea turtle conservation. Oryx, 54(3), 287-289.
Doherty PD, Broderick AC, Godley BJ, Hart KA, Phillips Q, Sanghera A, Stringell TB, Walker JT, Richardson PB (2020). Spatial Ecology of Sub-Adult Green Turtles in Coastal Waters of the Turks and Caicos Islands: Implications for Conservation Management. Frontiers in Marine Science, 7
Haywood JC, Fuller WJ, Godley BJ, Margaritoulis D, Shutler JD, Snape RTE, Widdicombe S, Zbinden JA, Broderick AC (2020). Spatial ecology of loggerhead turtles: Insights from stable isotope markers and satellite telemetry.
Diversity and Distributions,
26(3), 368-381.
Abstract:
Spatial ecology of loggerhead turtles: Insights from stable isotope markers and satellite telemetry
Aim: Using a combination of satellite telemetry and stable isotope analysis (SIA), our aim was to identify foraging grounds of loggerhead turtles (Caretta caretta) at important rookeries in the Mediterranean, examine foraging ground fidelity, and across 25 years determine the proportion of nesting females recruiting from each foraging region to a major rookery in Cyprus. Location: Mediterranean Sea. Methods: Between 1993 and 2018, we investigated the spatial ecology of loggerhead turtles from rookeries in Cyprus and Greece using satellite telemetry (n = 55 adults) and SIA of three elements (n = 296). Results: Satellite telemetry from both rookeries revealed the main foraging areas as the Adriatic region (Cyprus: 4% of individuals, Greece: 55%), Tunisian Plateau (Cyprus: 16%, Greece: 40%) and the eastern Mediterranean (Cyprus: 80%, Greece: 5%). Combining satellite telemetry and SIA allowed 64% of all nesting females to be assigned to; the Adriatic region (Cyprus: 2%, Greece: 38.5%), Tunisian Plateau (Cyprus: 47%, Greece: 38.5%) and the eastern Mediterranean (Cyprus: 51%, Greece: 23%), which are markedly different to proportions obtained using satellite telemetry. The proportion of the Cyprus nesting cohort using each foraging region did not change significantly, with the exception that individuals foraging in the Adriatic region are only present in the Cyprus nesting population from 2012. Repeat satellite tracking (n = 3) and temporal consistency in isotope ratios (n = 36) of Cyprus females, strongly suggest foraging ground fidelity over multiple decades. Main conclusions: This study demonstrates the advantages of combining satellite telemetry and SIA to investigate spatial ecology at a population level. The importance of the Tunisian Plateau for foraging is demonstrated. This study indicates that females generally show high fidelity to foraging grounds and shows a potential recent shift to foraging in the Adriatic region for Cyprus females, while the importance of other regions persists across decades, thus providing baselines to develop and assess conservation strategies.
Abstract.
Collins C, Bech Letessier T, Broderick A, Wijesundara I, Nuno A (2020). Using perceptions to examine human responses to blanket bans: the case of the thresher shark landing-ban in Sri Lanka.
Marine Policy,
121Abstract:
Using perceptions to examine human responses to blanket bans: the case of the thresher shark landing-ban in Sri Lanka
Species-specific bans are increasingly being implemented to stem loss of vulnerable marine species, but there is a paucity of evaluative research into resulting socio-economic and ecological consequences. In 2012, a blanket ban on landing Alopiidae (thresher) sharks was introduced in Sri Lanka. We used fisher perceptions, shown to influence support and compliance with conservation policies, to examine human responses. Data, gathered over a ten-month period in 2019 from focus groups and informal engagement during site visits, suggest support for the ban was lowest amongst fishers who perceived negative social consequences to be higher. Perceptions were also undermined by feelings of poor engagement from institutions and a lack of ecological necessity. The ban appears effective in halting targeted fisheries; however, persistent bycatch was reported by fishers. Further, bycatch appears to be widely unrecorded partly owing to mistrust and confusion amongst fishers. Occasional illegal landings were reported, seemingly motivated by interlinked factors such as good economic returns for thresher meat and high vessel running costs. The potential severity and inequity in social consequences stemming from blanket bans was highlighted, particularly when bycatch and targeted fisheries co-exist. Case study lessons are translated into a checklist containing key questions, designed to aid policy-makers to assess data provision and needs prior to introducing bans. Increasing data provision could enhance the capability of policies to predict and adapt to human behavioural responses, a key requirement considering continuing global declines in sharks despite increasing conservation effort.
Abstract.
Cerritelli G, Bianco G, Santini G, Broderick AC, Godley BJ, Hays GC, Luschi P, Åkesson S (2019). Assessing reliance on vector navigation in the long-distance oceanic migrations of green sea turtles.
Behavioral Ecology,
30(1), 68-79.
Abstract:
Assessing reliance on vector navigation in the long-distance oceanic migrations of green sea turtles
Vector navigation, i.e. maintaining a constant heading for a given amount of time, is hypothesized to provide a viable basis for the navigational feats of a number of long-distance animal migrants. Since animals following this strategy are subject to drift by wind or by ocean current, performing long migrations relying on vector navigation is particularly challenging. We tested whether vector navigation could be involved in the migrations of green turtles (Chelonia mydas) that migrate between the remote Ascension Island and Brazil. To this aim, a novel approach was followed using individual-based numerical models to simulate migratory trajectories of virtual turtles that were compared to actual routes reconstructed by satellite. Simulated postnesting migrations from Ascension revealed that weak currents enabled modeled turtles to reach the Brazilian coast, but only for a limited range of headings around due West. This conclusion was corroborated by comparing modeled trajectories with the actual routes of previously tracked turtles, with a beeline vector navigation strategy providing the best fit, although a true-navigation strategy directed to the landfall site produced similar results. Finally, we tested if a vector navigational strategy was feasible for the prebreeding migration from Brazil towards Ascension, but modeled routes mostly failed to reach the island or a larger area around it, with individuals drifting away under the influence of currents. We conclude that Ascension turtles can take advantage of vector navigation when migrating towards a wide target like the Brazilian coast, while the demanding prebreeding migration likely requires more complex navigational systems.
Abstract.
Patrício AR, Varela MR, Barbosa C, Broderick AC, Catry P, Hawkes LA, Regalla A, Godley BJ (2019). Climate change resilience of a globally important sea turtle nesting population.
Glob Chang Biol,
25(2), 522-535.
Abstract:
Climate change resilience of a globally important sea turtle nesting population.
Few studies have looked into climate change resilience of populations of wild animals. We use a model higher vertebrate, the green sea turtle, as its life history is fundamentally affected by climatic conditions, including temperature-dependent sex determination and obligate use of beaches subject to sea level rise (SLR). We use empirical data from a globally important population in West Africa to assess resistance to climate change within a quantitative framework. We project 200 years of primary sex ratios (1900-2100) and create a digital elevation model of the nesting beach to estimate impacts of projected SLR. Primary sex ratio is currently almost balanced, with 52% of hatchlings produced being female. Under IPCC models, we predict: (a) an increase in the proportion of females by 2100 to 76%-93%, but cooler temperatures, both at the end of the nesting season and in shaded areas, will guarantee male hatchling production; (b) IPCC SLR scenarios will lead to 33.4%-43.0% loss of the current nesting area; (c) climate change will contribute to population growth through population feminization, with 32%-64% more nesting females expected by 2120; (d) as incubation temperatures approach lethal levels, however, the population will cease growing and start to decline. Taken together with other factors (degree of foraging plasticity, rookery size and trajectory, and prevailing threats), this nesting population should resist climate change until 2100, and the availability of spatial and temporal microrefugia indicates potential for resilience to predicted impacts, through the evolution of nest site selection or changes in nesting phenology. This represents the most comprehensive assessment to date of climate change resilience of a marine reptile using the most up-to-date IPCC models, appraising the impacts of temperature and SLR, integrated with additional ecological and demographic parameters. We suggest this as a framework for other populations, species and taxa.
Abstract.
Author URL.
Maxwell SM, Broderick AC, Dutton PH, Fossette-Halot S, Fuentes MMPB, Reina RD (2019). Editorial: Advances in the Biology and Conservation of Marine Turtles.
FRONTIERS IN MARINE SCIENCE,
6 Author URL.
Barbanti A, Turmo M, Blumenthal J, Boyle J, Broderick A, Collyer L, Ebanks-Petrie G, Godley B, Pascual M, Carreras C, et al (2019). Founding in action: genetic assessment of new populations from the same reintroduction program. Frontiers in Marine Science, 6
Haywood J, Fuller W, Godley B, Shutler J, Widdicombe S, Broderick A (2019). Global review and inventory: how stable isotopes are helping us understand ecology and inform conservation of marine turtles. Marine Ecology Progress Series, 613, 217-245.
Barbanti A, Martin C, Blumenthal JM, Boyle J, Broderick AC, Collyer L, Ebanks-Petrie G, Godley BJ, Mustin W, Ordóñez V, et al (2019). How many came home? Evaluating ex situ conservation of green turtles in the Cayman Islands.
Mol Ecol,
28(7), 1637-1651.
Abstract:
How many came home? Evaluating ex situ conservation of green turtles in the Cayman Islands.
Ex situ management is an important conservation tool that allows the preservation of biological diversity outside natural habitats while supporting survival in the wild. Captive breeding followed by re-introduction is a possible approach for endangered species conservation and preservation of genetic variability. The Cayman Turtle Centre Ltd was established in 1968 to market green turtle (Chelonia mydas) meat and other products and replenish wild populations, thought to be locally extirpated, through captive breeding. We evaluated the effects of this re-introduction programmme using molecular markers (13 microsatellites, 800-bp D-loop and simple tandem repeat mitochondrial DNA sequences) from captive breeders (N = 257) and wild nesting females (N = 57) (sampling period: 2013-2015). We divided the captive breeders into three groups: founders (from the original stock), and then two subdivisions of F1 individuals corresponding to two different management strategies, cohort 1995 ("C1995") and multicohort F1 ("MCF1"). Loss of genetic variability and increased relatedness was observed in the captive stock over time. We found no significant differences in diversity among captive and wild groups, and similar or higher levels of haplotype variability when compared to other natural populations. Using parentage and sibship assignment, we determined that 90% of the wild individuals were related to the captive stock. Our results suggest a strong impact of the re-introduction programmme on the present recovery of the wild green turtle population nesting in the Cayman Islands. Moreover, genetic relatedness analyses of captive populations are necessary to improve future management actions to maintain genetic diversity in the long term and avoid inbreeding depression.
Abstract.
Author URL.
Duncan EM, Broderick AC, Fuller WJ, Galloway TS, Godfrey MH, Hamann M, Limpus CJ, Lindeque PK, Mayes AG, Omeyer LCM, et al (2019). Microplastic ingestion ubiquitous in marine turtles.
Glob Chang Biol,
25(2), 744-752.
Abstract:
Microplastic ingestion ubiquitous in marine turtles.
Despite concerns regarding the environmental impacts of microplastics, knowledge of the incidence and levels of synthetic particles in large marine vertebrates is lacking. Here, we utilize an optimized enzymatic digestion methodology, previously developed for zooplankton, to explore whether synthetic particles could be isolated from marine turtle ingesta. We report the presence of synthetic particles in every turtle subjected to investigation (n = 102) which included individuals from all seven species of marine turtle, sampled from three ocean basins (Atlantic [ATL]: n = 30, four species; Mediterranean (MED): n = 56, two species; Pacific (PAC): n = 16, five species). Most particles (n = 811) were fibres (ATL: 77.1% MED: 85.3% PAC: 64.8%) with blue and black being the dominant colours. In lesser quantities were fragments (ATL: 22.9%: MED: 14.7% PAC: 20.2%) and microbeads (4.8%; PAC only; to our knowledge the first isolation of microbeads from marine megavertebrates). Fourier transform infrared spectroscopy (FT-IR) of a subsample of particles (n = 169) showed a range of synthetic materials such as elastomers (MED: 61.2%; PAC: 3.4%), thermoplastics (ATL: 36.8%: MED: 20.7% PAC: 27.7%) and synthetic regenerated cellulosic fibres (SRCF; ATL: 63.2%: MED: 5.8% PAC: 68.9%). Synthetic particles being isolated from species occupying different trophic levels suggest the possibility of multiple ingestion pathways. These include exposure from polluted seawater and sediments and/or additional trophic transfer from contaminated prey/forage items. We assess the likelihood that microplastic ingestion presents a significant conservation problem at current levels compared to other anthropogenic threats.
Abstract.
Author URL.
Tilley D, Ball S, Ellick J, Godley BJ, Weber N, Weber SB, Broderick AC (2019). No evidence of fine scale thermal adaptation in green turtles.
Journal of Experimental Marine Biology and Ecology,
514-515, 110-117.
Abstract:
No evidence of fine scale thermal adaptation in green turtles
Adaptation to increasing temperatures may enable species to mitigate the long-term impacts of climate change. Sea turtles have temperature dependent sex determination (TSD) and variation in the thermal reaction norm, which influences offspring sex ratio, has been suggested as a potential adaptive mechanism to rising global temperatures. Here, we investigate the sex ratio of green turtle Chelonia mydas offspring from nests on beaches with notable differences in their thermal properties, to look for evidence of localised adaptation. We compared pivotal temperatures and hatch success in both the laboratory and in situ using eggs laid on two nesting beaches (dark vs. pale sand) at Ascension Island that represent the extremes of the range of incubation temperatures experienced by this population. We found no effect of beach of origin on pivotal temperatures, hatch success, or hatchling size in the laboratory or the wild. This suggests that turtles from the same rookery are not locally adapted to different thermal conditions experienced during incubation. Under predicted climate change scenarios, this will result in reduced hatch success and an increased proportion of female offspring unless temporal or spatial range shifts occur.
Abstract.
Omeyer LCM, Broderick AC, Godley BJ, Snape RTE, Fuller WJ (2019). The effect of biologging systems on reproduction, growth and survival of adult sea turtles.
Movement Ecology,
7(2), 1-12.
Abstract:
The effect of biologging systems on reproduction, growth and survival of adult sea turtles
Background:. Telemetry and biologging systems, ‘tracking’ hereafter, have been instrumental in meeting the challenges associated with studying the ecology and behaviour of cryptic, wide-ranging marine mega-vertebrates. Over recent decades, globally, sea turtle tracking has increased exponentially, across species and life-stages, despite a paucity of studies investigating the effects of such devices on study animals. Indeed, such studies are key to informing whether data collected are unbiased and, whether derived estimates can be considered typical of the population at large.
Methods:. Here, using a 26-year individual-based monitoring dataset on sympatric green (Chelonia mydas) and loggerhead (Caretta caretta) turtles, we provide the first analysis of the effects of device attachment on reproduction, growth and survival of nesting females.
Results:. We found no significant difference in growth and reproductive correlates between tracked and non-tracked females in the years following device attachment. Similarly, when comparing pre- and post-tracking data, we found no significant difference in the reproductive correlates of tracked females for either species or significant carry-over effects of device attachment on reproductive correlates in green turtles. The latter was not investigated for loggerhead turtles due to small sample size. Finally, we found no significant effects of device attachment on return rates or survival of tracked females for either species.
Conclusion:. While there were no significant detrimental effects of device attachment on adult sea turtles in this region, our study highlights the need for other similar studies elsewhere and the value of long-term individual-based monitoring.
Abstract.
Omeyer LCM, Casale P, Fuller WJ, Godley BJ, Holmes KE, Snape RTE, Broderick AC (2019). The importance of passive integrated transponder (PIT) tags for measuring life-history traits of sea turtles.
Biological Conservation,
240Abstract:
The importance of passive integrated transponder (PIT) tags for measuring life-history traits of sea turtles
© 2019 the Authors Capture-mark-recapture studies rely on the identification of individuals through time, using markers or tags, which are assumed to be retained. This assumption, however, may be violated, having implications for population models. In sea turtles, individual identification is typically based on external flipper tags, which can be combined with internal passive integrated transponder (PIT) tags. Despite the extensive use of flipper tags, few studies have modelled tag loss using continuous functions. Using a 26-year dataset for sympatrically nesting green (Chelonia mydas) and loggerhead (Caretta caretta) turtles, this study aims to assess how PIT tag use increases the accuracy of estimates of life-history traits. The addition of PIT tags improved female identification: between 2000 and 2017, 53% of green turtles and 29% of loggerhead turtles were identified from PIT tags alone. We found flipper and PIT tag losses were best described by decreasing logistic curves with lower asymptotes. Excluding PIT tags from our dataset led to underestimation of flipper tag loss, reproductive periodicity, reproductive longevity and annual survival, and overestimation of female abundance and recruitment for both species. This shows the importance of PIT tags in improving the accuracy of estimates of life-history traits. Thus, estimates where tag loss has not been corrected for should be interpreted with caution and could bias IUCN Red List assessments. As such, long-term population monitoring programmes should aim to estimate tag loss and assess the impact of loss on life-history estimates, to provide robust estimates without which population models and stock assessments cannot be derived accurately.
Abstract.
Colman LP, Thomé JCA, Almeida ADP, Baptistotte C, Paulo PC, Broderick AC, Ribeiro FA, Vila-Verde L, Godley BJ (2019). Thirty years of leatherback turtle Dermochelys coriacea nesting in Espírito Santo, Brazil, 1988-2017: Reproductive biology and conservation.
Endangered Species Research,
39, 147-158.
Abstract:
Thirty years of leatherback turtle Dermochelys coriacea nesting in Espírito Santo, Brazil, 1988-2017: Reproductive biology and conservation
In the southwestern Atlantic Ocean, leatherback turtles Dermochelys coriacea are only known to regularly nest in eastern Brazil, on the coast of the state of Espírito Santo. Here, we present an analysis of the nesting ecology, population trends and conservation status of this leather - back turtle colony between 1988 and 2017. We observed an increasing, although variable, trend in the annual number of nests, with the mean increasing from 25.6 nests in the first 5 yr of the study to 89.8 in the last 5 yr. Concurrently, there was also a significant decrease in the mean curved carapace length of the population, which we hypothesize was caused by recruitment of new females to the nesting population. Throughout the study period, nests were concentrated in the southern part of the 160 km long study area. No change was observed in the annual median nesting date. Mean annual hatching success was 66.0% and no significant variation in hatching success was detected after a major spill of mining tailings into the nesting area in 2015. We postulate that local conservation actions that started in the 1980s have contributed to the gentle recovery of this population; however, given the small population size and restricted nesting geographical distribution alongside the persistence of various threats-fisheries bycatch, climate change, pollution and coastal development-this population continues to be of conservation concern.
Abstract.
Snape RTE, Broderick AC, Çiçek BA, Fuller WJ, Tregenza N, Witt MJ, Godley BJ (2018). Conflict between Dolphins and a Data-Scarce Fishery of the European Union.
Human Ecology,
46(3), 423-433.
Abstract:
Conflict between Dolphins and a Data-Scarce Fishery of the European Union
Fisheries depredation by marine mammals is an economic concern worldwide. We combined questionnaires, acoustic monitoring, and participatory experiments to investigate the occurrence of bottlenose dolphins in the fisheries of Northern Cyprus, and the extent of their conflict with set-nets, an economically important metier of Mediterranean fisheries. Dolphins were present in fishing grounds throughout the year and were detected at 28% of sets. Net damage was on average six times greater where dolphins were present, was correlated with dolphin presence, and the associated costs were considerable. An acoustic deterrent pinger was tested, but had no significant effect although more powerful pingers could have greater impact. However, our findings indicate that effective management of fish stocks is urgently required to address the overexploitation that is likely driving depredation behaviour in dolphins, that in turn leads to net damage and the associated costs to the fisheries.
Abstract.
Bradshaw PJ, Broderick AC, Carreras C, Fuller W, Snape RTE, Wright LI, Godley BJ (2018). Defining conservation units with enhanced molecular tools to reveal fine scale structuring among Mediterranean green turtle rookeries.
Biological Conservation,
222, 253-260.
Abstract:
Defining conservation units with enhanced molecular tools to reveal fine scale structuring among Mediterranean green turtle rookeries
Understanding the connectivity among populations is a key research priority for species of conservation concern. Genetic tools are widely used for this purpose, but the results can be limited by the resolution of the genetic markers in relation to the species and geographic scale. Here, we investigated natal philopatry in green turtles (Chelonia mydas) from four rookeries within close geographic proximity (~200 km) on the Mediterranean island of Cyprus. We genotyped hypervariable mtSTRs, a mtDNA control region sequence (CR) and 13 microsatellite loci to genetically characterise 479 green turtles using markers with different modes of inheritance. We demonstrated matrilineal stock structure for the first time among Mediterranean green turtle rookeries. This result contradicts previous regional assessments and supports a growing body of evidence that green turtles exhibit a more precise level of natal site fidelity than has commonly been recognised. The microsatellites detected weak male philopatry with significant stock structure among three of the six pairwise comparisons. The absence of Atlantic CR haplotypes and mtSTRs amongst these robust sample sizes reaffirms the reproductive isolation of Mediterranean green turtles and supports their status as a subpopulation. A power analysis effectively demonstrated that the mtDNA genetic markers previously employed to evaluate regional stock identity were confounded by an insufficient resolution considering the recent colonisation of this region. These findings improve the regional understanding of stock connectivity and illustrate the importance of using suitable genetic markers to define appropriate units for management and conservation.
Abstract.
Omeyer LCM, Fuller WJ, Godley BJ, Snape RTE, Broderick AC (2018). Determinate or indeterminate growth? Revisiting the growth strategy of sea turtles.
Marine Ecology Progress Series,
596, 199-211.
Abstract:
Determinate or indeterminate growth? Revisiting the growth strategy of sea turtles
Traditionally, growth can be either determinate, ceasing during the natural lifespan of individuals, or indeterminate, persisting throughout life. Although indeterminate growth is a widely accepted strategy and believed to be ubiquitous among long-lived species, it may not be as common as previously thought. Sea turtles are believed to be indeterminate growers despite the paucity of long-term studies into post-maturity growth. In this study, we provide the first temporal analysis of post-maturity growth rates in wild living sea turtles, using 26 yr of data on individual measurements of females nesting in Cyprus. We used generalised additive/linear mixed models to incorporate multiple growth measurements for each female and model post-maturity growth over time. We found post-maturity growth to persist in green Chelonia mydas and loggerhead Caretta caretta turtles, with growth decreasing for approximately 14 yr before plateauing around zero for a further decade solely in green turtles. We also found growth to be independent of size at sexual maturity in both species. Additionally, although annual growth and compound annual growth rates were higher in green turtles than in loggerhead turtles, this difference was not statistically significant. While indeterminate growth is believed to be a key life-history trait of ectothermic vertebrates, here, we provide evidence of determinate growth in green and loggerhead turtles and suggest that determinate growth is a life-history trait shared by cheloniid species. Our results highlight the need for long-term studies to refine life-history models and further our understanding of ageing and longevity of wild sea turtles for conservation and management.
Abstract.
Casale P, Broderick AC, Camiñas JA, Cardona L, Carreras C, Demetropoulos A, Fuller WJ, Godley BJ, Hochscheid S, Kaska Y, et al (2018). Mediterranean sea turtles: Current knowledge and priorities for conservation and research.
Endangered Species Research,
36, 229-267.
Abstract:
Mediterranean sea turtles: Current knowledge and priorities for conservation and research
© the authors 2018. The available information regarding the 2 sea turtle species breeding in the Mediterranean (loggerhead turtle Caretta caretta and green turtle Chelonia mydas) is reviewed, including biometrics and morphology, identification of breeding and foraging areas, ecology and behaviour, abundance and trends, population structure and dynamics, anthropogenic threats and conservation measures. Although a large body of knowledge has been generated, research efforts have been inconsistently allocated across geographic areas, species and topics. Significant gaps still exist, ranging from the most fundamental aspects, such as the distribution of major nesting sites and the total number of clutches laid annually in the region, to more specific topics like age at maturity, survival rates and behavioural ecology, especially for certain areas (e.g. south-eastern Mediterranean). These gaps are particularly marked for the green turtle. The recent positive trends of nest counts at some nesting sites may be the result of the cessation of past exploitation and decades of conservation measures on land, both in the form of national regulations and of continued active protection of clutches. Therefore, the current status should be considered as dependent on such ongoing conservation efforts. Mitigation of incidental catch in fisheries, the main anthropogenic threat at sea, is still in its infancy. From the analysis of the present status a comprehensive list of re search and conservation priorities is proposed.
Abstract.
Tikochinski Y, Bradshaw P, Mastrogiacomo A, Broderick A, Daya A, Demetropoulos A, Demetropoulos S, Eliades NG, Fuller W, Godley B, et al (2018). Mitochondrial DNA short tandem repeats unveil hidden population structuring and migration routes of an endangered marine turtle.
Aquatic Conservation: Marine and Freshwater Ecosystems,
28(4), 788-797.
Abstract:
Mitochondrial DNA short tandem repeats unveil hidden population structuring and migration routes of an endangered marine turtle
The assessment of the composition and dynamics of endangered populations is crucial for management and conservation, and appropriate genetic markers are critical. The genetic structuring of the Mediterranean green turtle (Chelonia mydas) populations and the origin of the stranded animals found along the Israeli coast was investigated using new highly polymorphic short tandem repeat (STR) markers. The structuring of nesting populations was studied using pairwise genetic distances and a principal coordinates analysis (PCoA). The contribution of the different nesting populations to the stranded sample was assessed by using a mixed-stock analysis. A clear population genetic structure, not detected before, has been revealed. The four nesting populations are genetically well differentiated, and thus should be considered as different management units. The populations from Turkey and Israel showed higher resemblance, despite residing at opposite ends of the Mediterranean distribution. The Turkish nesting population is the main source of the stranded turtles sampled along the Israeli shore, confirming that individuals from this population migrate from north to south along the eastern shore of the Mediterranean, as previously shown by telemetry studies. The use of a highly polymorphic haplotyping method enabled the detection of a clear genetic structuring of the green turtle populations in the eastern Mediterranean Sea that was not revealed in previous studies, demonstrating the importance of marker selection in population genetics. The analysis of the genetic composition of the stranded turtles allowed us to investigate the migration patterns from nesting to foraging areas, supporting previous satellite-tracking and stable-isotope results. These results will help to delineate conservation management units for the species in the Mediterranean, and reveal connectivity among beaches and mixed aggregations.
Abstract.
Patrício AR, Varela MR, Barbosa C, Broderick AC, Ferreira Airaud MB, Godley BJ, Regalla A, Tilley D, Catry P (2018). Nest site selection repeatability of green turtles, Chelonia mydas, and consequences for offspring.
Animal Behaviour,
139, 91-102.
Abstract:
Nest site selection repeatability of green turtles, Chelonia mydas, and consequences for offspring
Nest site selection is a critical behaviour, particularly in species with no parental care, as it can greatly impact offspring survival. Marine turtles depend on sandy beaches to nest, where they select from a range of microhabitats that may differently affect hatchling survival and phenotype. Here we describe the degree of nest site selection at one of the largest green turtle rookeries globally, in Guinea-Bissau, West Africa, and how this impacts offspring. In 2013 and 2014 we recorded the spatial distribution of 1559 nests, and monitored 657 females during oviposition, to assess population and individual preferences on nesting site. Overall, females tended to nest close to the vegetation, at a preferred elevation of 4.8–5.0 m, which was above the highest spring tide (4.7 m), enhancing clutch survival. Individuals displayed high repeatability in nesting microhabitat type (open sand, forest border and forest), distance along the beach, distance to the vegetation and elevation, which may result from this behaviour having a genetic basis or from fine-scale nest site philopatry. Hatchlings from cooler nests were larger, potentially dispersing faster and more able to evade predators, while smaller hatchlings, from warmer nests, retained more energetic reserves (residual yolk), which may also be advantageous for initial dispersal, particularly if food is scarce. Thus, individual preferences in nest site selection led to trade-offs in offspring phenotype, but overall, most nesting females selected sites that increased offspring survival, suggesting that nest site selection is an adaptive trait that has been under selection. As under future climate change scenarios females nesting in upper shaded areas should have higher fitness, individual consistency in nesting microhabitat provides opportunity for natural selection to occur.
Abstract.
Snape RTE, Bradshaw PJ, Broderick AC, Fuller WJ, Stokes KL, Godley BJ (2018). Off-the-shelf GPS technology to inform marine protected areas for marine turtles.
Biological Conservation,
227, 301-309.
Abstract:
Off-the-shelf GPS technology to inform marine protected areas for marine turtles
The financial expense of tracking solutions often impedes effective characterisation of habitat use in threatened marine megavertebrates. Yet some of these taxa predictably aggregate at coastal breeding sites, providing conservation opportunities. Toward a low-cost solution for tracking marine megavertebrates, we trial conventional GPS data loggers against Argos satellite transmitters for assessing inter-nesting habitat use of marine turtles. Devices were attached to green (Chelonia mydas) and loggerhead (Caretta caretta) turtles nesting at a study site in Cyprus, where patrol teams were in place to retrieve GPS loggers from turtles returning to lay subsequent clutches. GPS tracking revealed loggerhead turtles to predominantly use areas outside the boundaries of an MPA proposed for the region, while both species under-used much of the MPA area. Due to high location error, Argos data were considered unsuitable for such fine-scale assessments (all location classes except Z were included in our analysis). However, Argos tracking showed half the loggerhead turtles sampled also nested outside of the patrolled study area, demonstrating connectivity with other proposed MPAs. This was not accounted for by GPS tracking, because females exhibiting this behaviour rarely returned to the study beach, precluding GPS retrieval, thus, demonstrating the power of remote data access. The low-cost GPS technology could be considered in similar cases, where recapture is likely and where funding barriers preclude the use of Argos-relay fast-acquisition GPS technology. In combining the accuracy GPS and the continuity of Argos, the latter provides the best solution in most scenarios, but at far greater cost.
Abstract.
Oppel S, Bolton M, Carneiro APB, Dias MP, Green JA, Masello JF, Phillips RA, Owen E, Quillfeldt P, Beard A, et al (2018). Spatial scales of marine conservation management for breeding seabirds.
Marine Policy,
98, 37-46.
Abstract:
Spatial scales of marine conservation management for breeding seabirds
Knowing the spatial scales at which effective management can be implemented is fundamental for conservation planning. This is especially important for mobile species, which can be exposed to threats across large areas, but the space use requirements of different species can vary to an extent that might render some management approaches inefficient. Here the space use patterns of seabirds were examined to provide guidance on whether conservation management approaches should be tailored for taxonomic groups with different movement characteristics. Seabird tracking data were synthesised from 5419 adult breeding individuals of 52 species in ten families that were collected in the Atlantic Ocean basin between 1998 and 2017. Two key aspects of spatial distribution were quantified, namely how far seabirds ranged from their colony, and to what extent individuals from the same colony used the same areas at sea. There was evidence for substantial differences in patterns of space-use among the ten studied seabird families, indicating that several alternative conservation management approaches are needed. Several species exhibited large foraging ranges and little aggregation at sea, indicating that area-based conservation solutions would have to be extremely large to adequately protect such species. The results highlight that short-ranging and aggregating species such as cormorants, auks, some penguins, and gulls would benefit from conservation approaches at relatively small spatial scales during their breeding season. However, improved regulation of fisheries, bycatch, pollution and other threats over large spatial scales will be needed for wide-ranging and dispersed species such as albatrosses, petrels, storm petrels and frigatebirds.
Abstract.
Rees AF, Avens L, Ballorain K, Bevan E, Broderick AC, Carthy RR, Christianen MJA, Duclos G, Heithaus MR, Johnston DW, et al (2018). The potential of unmanned aerial systems for sea turtle research and conservation: a review and future directions.
Endangered Species Research,
35, 81-100.
Abstract:
The potential of unmanned aerial systems for sea turtle research and conservation: a review and future directions
© the authors 2018. The use of satellite systems and manned aircraft surveys for remote data collection has been shown to be transformative for sea turtle conservation and research by enabling the collection of data on turtles and their habitats over larger areas than can be achieved by surveys on foot or by boat. Unmanned aerial vehicles (UAVs) or drones are increasingly being adopted to gather data, at previously unprecedented spatial and temporal resolutions in diverse geographic locations. This easily accessible, low-cost tool is improving existing research methods and enabling novel approaches in marine turtle ecology and conservation. Here we review the diverse ways in which incorporating inexpensive UAVs may reduce costs and field time while improving safety and data quality and quantity over existing methods for studies on turtle nesting, at-sea distribution and behaviour surveys, as well as expanding into new avenues such as surveillance against illegal take. Furthermore, we highlight the impact that high-quality aerial imagery captured by UAVs can have for public outreach and engagement. This technology does not come without challenges. We discuss the potential constraints of these systems within the ethical and legal frameworks which researchers must operate and the difficulties that can result with regard to storage and analysis of large amounts of imagery. We then suggest areas where technological development could further expand the utility of UAVs as data-gathering tools; for example, functioning as downloading nodes for data collected by sensors placed on turtles. Development of methods for the use of UAVs in sea turtle research will serve as case studies for use with other marine and terrestrial taxa.
Abstract.
Duncan EM, Arrowsmith J, Bain C, Broderick AC, Lee J, Metcalfe K, Pikesley SK, Snape RTE, van Sebille E, Godley BJ, et al (2018). The true depth of the Mediterranean plastic problem: Extreme microplastic pollution on marine turtle nesting beaches in Cyprus.
Marine Pollution Bulletin,
136, 334-340.
Abstract:
The true depth of the Mediterranean plastic problem: Extreme microplastic pollution on marine turtle nesting beaches in Cyprus
We sampled 17 nesting sites for loggerhead (Caretta caretta) and green turtles (Chelonia mydas) in Cyprus. Microplastics (
Abstract.
Nuno A, Blumenthal JM, Austin TJ, Bothwell J, Ebanks-Petrie G, Godley BJ, Broderick AC (2018). Understanding implications of consumer behavior for wildlife farming and sustainable wildlife trade.
Conserv Biol,
32(2), 390-400.
Abstract:
Understanding implications of consumer behavior for wildlife farming and sustainable wildlife trade.
Unsustainable wildlife trade affects biodiversity and the livelihoods of communities dependent upon those resources. Wildlife farming has been proposed to promote sustainable trade, but characterizing markets and understanding consumer behavior remain neglected but essential steps in the design and evaluation of such operations. We used sea turtle trade in the Cayman Islands, where turtles have been farm raised for human consumption for almost 50 years, as a case study to explore consumer preferences toward wild-sourced (illegal) and farmed (legal) products and potential conservation implications. Combining methods innovatively (including indirect questioning and choice experiments), we conducted a nationwide trade assessment through in-person interviews from September to December 2014. Households were randomly selected using disproportionate stratified sampling, and responses were weighted based on district population size. We approached 597 individuals, of which 37 (6.2%) refused to participate. Although 30% of households had consumed turtle in the previous 12 months, the purchase and consumption of wild products was rare (e.g. 64-742 resident households consumed wild turtle meat [i.e. 0.3-3.5% of households] but represented a large threat to wild turtles in the area due to their reduced populations). Differences among groups of consumers were marked, as identified through choice experiments, and price and source of product played important roles in their decisions. Despite the long-term practice of farming turtles, 13.5% of consumers showed a strong preference for wild products, which demonstrates the limitations of wildlife farming as a single tool for sustainable wildlife trade. By using a combination of indirect questioning, choice experiments, and sales data to investigate demand for wildlife products, we obtained insights about consumer behavior that can be used to develop conservation-demand-focused initiatives. Lack of data from long-term social-ecological assessments hinders the evaluation of and learning from wildlife farming. This information is key to understanding under which conditions different interventions (e.g. bans, wildlife farming, social marketing) are likely to succeed.
Abstract.
Author URL.
Duncan EM, Botterell ZLR, Broderick AC, Galloway TS, Lindeque PK, Nuno A, Godley BJ (2017). A global review of marine turtle entanglement in anthropogenic debris: a baseline for further action.
ENDANGERED SPECIES RESEARCH,
34, 431-448.
Author URL.
Weber SB, Weber N, Godley BJ, Pelembe T, Stroud S, Williams N, Broderick AC (2017). Ascension Island as a mid-Atlantic developmental habitat for juvenile hawksbill turtles.
Journal of the Marine Biological Association of the United Kingdom,
97(4), 813-820.
Abstract:
Ascension Island as a mid-Atlantic developmental habitat for juvenile hawksbill turtles
Ascension Island in the South Atlantic Ocean is renowned for its globally-important nesting population of green turtles (Chelonia mydas) that has been the subject of long-term research. By comparison, very little is known about the apparently small population of hawksbill turtles (Eretmochelys imbricata) that have been recorded in its waters, thousands of kilometres from known nesting beaches. Here, we collate 10 years of in-water tagging data, opportunistic public sighting records and underwater observations to provide a baseline for future research, and present preliminary data on habitat use derived from two individuals fitted with GPS transmitters. Although public sightings were inevitably biased towards popular recreation areas, the resulting distribution suggests that hawksbill turtles occur year round in Ascension Island's waters along the entire 65 km of coastline. Hawksbills were observed feeding on benthic algae and encrusting sponges, and were frequently seen scavenging on fish discards around the Island's pier at night aided by anthropogenic lighting. Between 2003 and 2013, 35 turtles were captured, measured, tagged and then released. Curved carapace lengths ranged from 33.5 to 85 cm (mean = 48.8 cm) indicating that most (if not all) individuals encountered around Ascension are post-pelagic juveniles. Four individuals were recaptured at least once giving a mean minimum residence time of 4.2 yr (range: 2.8-7.3 yr) and a mean growth rate of 2.8 cm yr-1. Turtles fitted with Fastloc™ GPS devices remained at Ascension Island for the duration of the study (>90 days) and occupied restricted home ranges with an average area of 2.5 km2 and an average 'core use area' (50% utilization distribution) of 0.05 km2. Together, these results suggest that Ascension Island serves as a mid-Atlantic developmental habitat for benthic-feeding, juvenile hawksbill turtles on extended oceanic migrations before recruiting to their adult foraging grounds, likely to be located in Brazil or tropical West Africa.
Abstract.
Humber F, Andriamahaino ET, Beriziny T, Botosoamananto R, Godley BJ, Gough C, Pedron S, Ramahery V, Broderick AC (2017). Assessing the small-scale shark fishery of Madagascar through community-based monitoring and knowledge.
Fisheries Research,
186, 131-143.
Abstract:
Assessing the small-scale shark fishery of Madagascar through community-based monitoring and knowledge
Over 90% of those employed in commercial capture fisheries work in the small-scale fisheries (SSF) sector and an estimated 97% of small scale fishers are found in least developed countries. However, the capacity for monitoring SSF globally is low and there is a paucity of data, in particular for remote areas within developing nations. The methods presented here demonstrate a low cost participatory approach for gathering data on small-scale fisheries, in particular for those that take place across remote areas. Community-based data collectors were trained to record biological and socioeconomic data on the traditional (non-motorised) shark fishery in the Toliara region of Madagascar over a six year period (2007–2012). An estimated 20 species of shark were recorded, of which 31% (n = 3505) were Sphyrna lewini (scalloped hammerhead), a species listed by the IUCN as Endangered (IUCN, 2016). Although the number of sharks landed annually has not decreased during our survey period, there was a significant decrease in the average size of sharks caught. Despite multiple anecdotal reports of shark population declines, interviews and focus groups highlight the possibility that shark landings appear to have been maintained through changes in gear and increases in effort (eg. number of fishers, time spent fishing), which may mask a decline in shark populations. The numbers of sharks taken by the traditional fishery in our study region was estimated to be between 65,000 and 104,000 year−1, whilst estimates using national export and import of dried shark fin from Madagascar, and shark length data in this study, put total landings between 78,000 and 471,851 year−1. Reliable data on the total volume of sharks landed in Madagascar's waters is scarce, in particular from foreign industrial boats both directly targeting shark species and as bycatch in fisheries targeting other species. There is currently no legislation in place to protect sharks from overexploitation in Madagascar and an urgent need to address the lack of shark fishery management across the traditional, artisanal and industrial fisheries.
Abstract.
Patrício AR, Marques A, Barbosa C, Broderick AC, Godley BJ, Hawkes LA, Rebelo R, Regalla A, Catry P (2017). Balanced primary sex ratios and resilience to climate change in a major sea turtle population.
Marine Ecology Progress Series,
577, 189-203.
Abstract:
Balanced primary sex ratios and resilience to climate change in a major sea turtle population
Global climate change is expected to have major impacts on biodiversity. Sea turtles have temperature-dependent sex determination, and many populations produce highly femalebiased offspring sex ratios, a skew likely to increase further with global warming. We estimated the primary sex ratio at one of the world's largest green turtle Chelonia mydas rookeries in Guinea-Bissau, West Africa, and explored its resilience to climate change. In 2013 and 2014, we deployed data loggers recording nest (n = 101) and sand (n = 30) temperatures, and identified hatchling sex by histological examination of gonads. A logistic curve was fitted to the data to allow predictions of sex ratio across habitats and through the nesting season. The population-specific pivotal temperature was 29.4°C, with both sexes produced within incubation temperatures from 27.6 to 31.4°C: the transitional range of temperatures (TRT). Primary sex ratio changed from maleto female-biased across relatively small temporal and spatial scales. Overall it was marginally female-biased, but we estimated an exceptionally high male hatchling production of 47.7% (95% CI: 36.7-58.3%) and 44.5% (95% CI: 33.8-55.4%) in 2013 and 2014, respectively. Both the temporal and spatial variation in incubation conditions and the wide range of the TRT suggest resilience and potential for adaptation to climate change if the present nesting habitat remains unchanged. These findings underline the importance of assessing site-specific parameters to understand populations' responses to climate change, particularly with regard to identifying rookeries with high male hatchling production that may be key for the future conservation of sea turtles under projected global warming scenarios.
Abstract.
Omeyer LCM, Godley BJ, Broderick AC (2017). Growth rates of adult sea turtles.
ENDANGERED SPECIES RESEARCH,
34, 357-371.
Author URL.
Humber F, Godley BJ, Nicolas T, Raynaud O, Pichon F, Broderick A (2017). Placing Madagascar's marine turtle populations in a regional context using community-based monitoring.
ORYX,
51(3), 542-553.
Abstract:
Placing Madagascar's marine turtle populations in a regional context using community-based monitoring
Madagascar is an important foraging ground for marine turtles in the Western Indian Ocean, yet the status of the country's nesting aggregations remains poorly documented. We assess the current status and trend in nesting throughout Madagascar, including data recorded by a community-based monitoring project in the Barren Isles (western Madagascar). We contextualize the findings in comparison with data from Madagascar's closest neighbouring states. Reports indicate that nesting levels have declined at many coastal sites, with no known recordings since 2000 at > 40 nesting sites. We estimate there are a minimum of 1,200 nests per year in Madagascar, with the largest recorded nesting aggregation (< 1,000 nests per year) found on islands off the west and northern coasts. The majority of nesting aggregations, including those recorded by the community-based monitoring project in the Barren Isles, are relatively small, in the order of < 50 nests per year, yet they are potentially important sources of regional genetic diversity. Nesting on many of the islands (e.g. Tromelin, Europa) around Madagascar has increased over the last 20 years, despite the fact that thousands of turtles probably originating from these sites are taken by fishers in the waters of Madagascar annually. We discuss the importance of protecting small nesting populations, and how community-based monitoring could be an important tool for conserving remote and vulnerable populations and building capacity for natural resource management.
Abstract.
Williams SM, Weber SB, Oppel S, Leat EHK, Sommerfeld J, Godley BJ, Weber N, Broderick AC (2017). Satellite Telemetry Reveals the First Record of the Ascension Frigatebird (Fregata aquila) for the Americas.
Wilson Journal of Ornithology,
129(3), 600-604.
Abstract:
Satellite Telemetry Reveals the First Record of the Ascension Frigatebird (Fregata aquila) for the Americas
We present the first record of the Ascension Frigatebird (Fregata aquila) for the Americas by retrieving coordinates from an individual equipped with a satellite transmitting device. As part of a wider study on the spatial and behavioral ecology of this species, we tracked a single juvenile frigatebird that entered into Brazilian waters as defined in the guidelines set forth by the Brazilian Ornithological Records Committee and the South American Checklist Committee. In total, this individual traveled ∼45,000 km over a 3.5-month period before transmissions ceased close to the exclusive economic zone of Sierra Leone. Based on the potential for this species to wander, the Ascension Frigatebird should be considered when attempting to identify any frigatebird in the Atlantic Ocean. Importantly, this record demonstrates the great potential for satellite telemetry to inform national ornithological and conservation organizations on the presence of pelagic seabirds that may otherwise be overlooked by visual surveys.
Abstract.
Bradshaw PJ, Broderick AC, Carreras C, Inger R, Fuller W, Snape R, Stokes KL, Godley BJ (2017). Satellite tracking and stable isotope analysis highlight differential recruitment among foraging areas in green turtles.
Marine Ecology Progress Series,
582, 201-214.
Abstract:
Satellite tracking and stable isotope analysis highlight differential recruitment among foraging areas in green turtles
© the authors 2017. Identifying links between breeding and non-breeding sites in migratory animals is an important step in understanding their ecology. Recognising the relative importance of foraging areas and ascertaining site-specific levels of recruitment can provide fundamental and applied insights. Here, satellite telemetry and the stable isotope ratios (δ13C, δ15N and δ34S) of 230 green turtles Chelonia mydas from a regionally important rookery in northern Cyprus were employed to evaluate the relative importance of 4 foraging areas. A preliminary analysis of stable isotope ratios suggested that a major foraging area had been missed through satellite telemetry as a large proportion of turtles had isotope ratios that did not correspond to sites previously identified. Stable isotope ratios were then employed to select 5 turtles to be fitted with platform terminal transmitters in 2015. All 5 turtles were subsequently tracked to the same location, Lake Bardawil in Egypt. Serially collected tissue samples from 45 females, ranging over 2 to 4 breeding seasons, suggested that foraging site fidelity was very common, with 82% of females exhibiting extremely high temporal consistency in isotope ratios. Quantifying fidelity allowed an evaluation of foraging area-specific contributions to each breeding cohort over the past 2 decades and demonstrated that recruitment was unequal among sites, and dynamic over time, with Egypt now currently the major contributor to the nesting aggregation. This work demonstrates the utility of stable isotope analysis to elucidate the spatial ecology of cryptic taxa and illustrates how more robust baselines can be assembled against which to measure the success of future marine conservation initiatives.
Abstract.
Oppel S, Weber S, Weber N, Fox D, Leat E, Sim J, Sommerfeld J, Bolton M, Broderick AC, Godley BJ, et al (2017). Seasonal shifts in foraging distribution due to individual flexibility in a tropical pelagic forager, the Ascension frigatebird.
Marine Ecology Progress Series,
585, 199-212.
Abstract:
Seasonal shifts in foraging distribution due to individual flexibility in a tropical pelagic forager, the Ascension frigatebird
Predators exploiting tropical pelagic waters characterised by low fluctuations in seasonal temperature and salinity may require different foraging strategies than predators that can rely on persistently productive marine features. Consistent individual differences in foraging strategies have been found in temperate seabirds, but it is unclear whether such foraging special-isation would be beneficial in unpredictable tropical pelagic waters. We examined whether foraging trip characteristics of a tropical seabird were consistent between seasons and within individuals and explored whether seasonal changes could be explained by environmental variables. Ascension frigatebird Fregata aquila trips lasted up to 18 d and covered a total travel distance of up to 7047 km, but adult frigatebirds stayed within a radius of 1150 km of Ascension Island. We found that the 50% utilisation distribution of the population expanded southwestward in the cool season due to individuals performing more and longer trips in a southerly and westerly direction during the cool compared to the hot season. Individual repeatability was low (R < 0.25) for all trip characteristics, and we were unable to explain seasonal changes in time spent at sea using oceanographic or atmospheric variables. Instead, frigatebird usage per area was almost exclusively determined by distance from the colony, and although individuals spent more time in distant portions of their foraging trips, the amount of time spent per unit area decreased exponentially with increasing distance from the colony. This study indicates that, in a relatively featureless environment, high individual consistency may not be a beneficial trait for pelagic predators.
Abstract.
Nelms SE, Duncan EM, Broderick AC, Galloway TS, Godfrey MH, Hamann M, Lindeque PK, Godley BJ (2016). Plastic and marine turtles: a review and call for research.
ICES JOURNAL OF MARINE SCIENCE,
73(2), 165-181.
Author URL.
Rees AF, Alfaro-Shigueto J, Barata PCR, Bjorndal KA, Bolten AB, Bourjea J, Broderick AC, Campbell LM, Cardona L, Carreras C, et al (2016). Review: Are we working towards global research priorities for management and conservation of sea turtles?. Endangered Species Research, 31, 337-382.
Snape RTE, Broderick AC, Çiçek BA, Fuller WJ, Glen F, Stokes K, Godley BJ (2016). Shelf life: Neritic habitat use of a turtle population highly threatened by fisheries.
Diversity and Distributions,
22(7), 797-807.
Abstract:
Shelf life: Neritic habitat use of a turtle population highly threatened by fisheries
Aim: it is difficult to mitigate threats to marine vertebrates until their habitat use is understood. We report on a decade of satellite tracking loggerhead turtles (Caretta caretta) from an important nesting site to determine priority habitats for their protection in a region where they are known to be heavily impacted by fisheries. Location: Cyprus, Eastern Mediterranean. Method: We tracked 27 adult female loggerheads between 2001 and 2012 from North Cyprus nesting beaches. To eliminate potential biases, we included females nesting on all coasts of our study area, at different periods of the nesting season and from a range of size classes. Results: Foraging sites were distributed over the continental shelf of Cyprus, the Levant and North Africa, up to a maximum distance of 2100 km from nesting sites. Foraging sites were clustered in (1) near-shore waters of Cyprus and Syria, (2) offshore waters of Egypt and (3) offshore and near-shore regions of Libya and Tunisia. The North Cyprus and west Egypt/east Libyan coasts are important areas for loggerhead turtles during migration. Movement patterns within foraging sites strongly suggest benthic feeding in discrete areas. Early nesters visited other rookeries in Turkey, Syria and Israel where they likely laid further clutches. Tracking suggests minimum annual mortality of 11%, comparable to other fishery-impacted loggerhead populations. Main conclusions: This work further highlights the importance of neritic habitats of Libya and Tunisia as areas likely used by loggerhead turtles from many of the Mediterranean rookeries and where the threat of fisheries bycatch is high. Our tracking data also suggest that anthropogenic mortalities may have occurred in North Cyprus, Syria and Egypt; all within near-shore marine areas where small-scale fisheries operate. Protection of this species across many geopolitical units is a major challenge and documenting their distribution is an important first step.
Abstract.
Hawkes LA, Witt MJ, Godley BJ, Broderick AC, McGowan A, Bjorndal KA, Bolten AB, Chaloupka M, Van Dam RP, Diez CE, et al (2016). Somatic growth dynamics of West Atlantic hawksbill sea turtles: a spatio-temporal perspective. Ecosphere, 7
Stringell TB, Clerveaux WV, Godley BJ, Kent FEA, Lewis EDG, Marsh JE, Phillips Q, Richardson PB, Sanghera A, Broderick AC, et al (2016). Taxonomic distinctness in the diet of two sympatric marine turtle species.
Marine Ecology,
37(5), 1036-1049.
Abstract:
Taxonomic distinctness in the diet of two sympatric marine turtle species
Marine turtles are considered keystone consumers in tropical coastal ecosystems and their decline through overexploitation has been implicated in the deterioration of reefs and seagrass pastures in the Caribbean. In the present study, we analysed stomach contents of green (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata) harvested in the legal turtle fishery of the Turks and Caicos Islands (Caribbean) during 2008–2010. Small juveniles to adult-sized turtles were sampled. Together with data from habitat surveys, we assessed diet composition and the taxonomic distinctness (and other species diversity measures) in the diets of these sympatric marine turtle species. The diet of green turtles (n�=�92) consisted of a total of 47 taxa: including three species of seagrass (present in 99% of individuals), 29 species of algae and eight sponge species. Hawksbill turtles (n�=�45) consumed 73 taxa and were largely spongivorous (16 species; sponges present in 100% of individuals) but also foraged on 50 species of algae (present in 73% of individuals) and three species of seagrass. Plastics were found in trace amounts in 4% of green turtle and 9% of hawksbill turtle stomach samples. We expected to find changes in diet that might reflect ontogenetic shifts from small (oceanic-pelagic) turtles to larger (coastal-benthic) turtles. Dietary composition (abundance and biomass), however, did not change significantly with turtle size, although average taxonomic distinctness was lower in larger green turtles. There was little overlap in prey between the two turtle species, suggesting niche separation. Taxonomic distinctness routines indicated that green turtles had the most selective diet, whereas hawksbill turtles were less selective than expected when compared with the relative frequency and biomass of diet items. We discuss these findings in relation to the likely important trophic roles that these sympatric turtle species play in reef and seagrass habitats.
Abstract.
Revuelta O, León YM, Broderick AC, Feliz P, Godley BJ, Balbuena JA, Mason A, Poulton K, Savoré S, Raga JA, et al (2015). Assessing the efficacy of direct conservation interventions: Clutch protection of the leatherback marine turtle in the Dominican Republic.
ORYX,
49(4), 677-686.
Abstract:
Assessing the efficacy of direct conservation interventions: Clutch protection of the leatherback marine turtle in the Dominican Republic
The beaches of Jaragua National Park in the Dominican Republic are the country's last known major nesting site for the leatherback marine turtle Dermochelys coriacea. This nesting aggregation is threatened by widespread illegal egg take, and clutch relocation and artificial incubation have been carried out as protection measures since 1974. We assess the efficacy of such efforts and investigate how artificial incubation may be influencing the success and sex ratios of clutches. We compare hatching success, incubation duration and embryo mortality in in-situ clutches (n = 43) with those incubated artificially at sites in the east and west of the Park (n = 35 and n = 31, respectively). Our results show that in the west, artificial incubation significantly decreases hatching success in clutches. In the east the duration of incubation is increased, which we predict would result in an increase in the number of males from these clutches. Clutch relocation is currently the only viable conservation option for clutches on eastern beaches because of illegal egg take but action is needed to ensure that the natural sex ratio is not distorted. However, on the western beaches in situ clutch incubation seems possible through beach protection. Further community engagement and enforcement are required to improve conservation measures at eastern beaches if long-term, less sustainable intervention is to be avoided.
Abstract.
Humber F, Andriamahefazafy M, Godley BJ, Broderick AC (2015). Endangered, essential and exploited: How extant laws are not enough to protect marine megafauna in Madagascar.
Marine Policy,
60, 70-83.
Abstract:
Endangered, essential and exploited: How extant laws are not enough to protect marine megafauna in Madagascar
The decline of many marine megafauna species is of global concern; but many of these species, in particular marine mammals, have been afforded international and national protection and are the focus of conservation programmes. The existing national and international legislation are reviewed through which marine megavertebrates are afforded protection in Malagasy waters. The decline and protection of marine megafauna has followed a familiar pattern in Madagascar, with two main exceptions: marine turtles and elasmobranchs remain heavily exploited by national and international fishing fleets. The status of legislation governing both taxa is unclear and unknown by many working within the fisheries and marine sector. In Madagascar, marine turtles are fully protected from exploitation by national regulations in conjunction with a number of multilateral agreements. The numerous pieces of legislation that protect marine turtles are not coherent, regularly misunderstood and rarely enforced. Madagascar is taking steps to improve protection of marine turtles through the development of a national strategy, but it is recommended that the opportunity is also taken to improve understanding of current legislation and work more closely with local communities that consider turtle fishing a customary practice. Elasmobranchs however, receive minimal legal protection and only those listed under multilateral agreements are bound by any potential future management. Where legislation does exist to help manage elasmobranchs (eg. bycatch stipulations for foreign fishing vessels) it is incomplete and difficult to enforce. It is also recommended that Madagascar puts in place national elasmobranch legislation to help prevent their continued overfishing, especially in the face of increasing numbers of elasmobranch species on CITES and CMS. As such, both groups of species are rendered effectively unprotected and are in danger of overexploitation. With the growth and proliferation of locally managed marine areas (LMMAs) in Madagascar the potential for local communities to increase protection and management of these species should be considered, especially with the limited capacity available to monitor and enforce legislation along such a vast coastline.
Abstract.
Hammerschlag N, Broderick AC, Coker JW, Coyne MS, Dodd M, Frick MG, Godfrey MH, Godley BJ, Griffin DB, Hartog K, et al (2015). Evaluating the landscape of fear between apex predatory sharks and mobile sea turtles across a large dynamic seascape.
Ecology,
96(8), 2117-2126.
Abstract:
Evaluating the landscape of fear between apex predatory sharks and mobile sea turtles across a large dynamic seascape
The “landscape of fear” model has been proposed as a unifying concept in ecology, describing, in part, how animals behave and move about in their environment. The basic model predicts that as an animal's landscape changes from low to high risk of predation, prey species will alter their behavior to risk avoidance. However, studies investigating and evaluating the landscape of fear model across large spatial scales (tens to hundreds of thousands of square kilometers) in dynamic, open, aquatic systems involving apex predators and highly mobile prey are lacking. To address this knowledge gap, we investigated predator–prey relationships between tiger sharks (Galeocerdo cuvier) and loggerhead turtles (Caretta caretta) in the North Atlantic Ocean. This included the use of satellite tracking to examine shark and turtle distributions as well as their surfacing behaviors under varying levels of home range overlap. Our findings revealed patterns that deviated from our a priori predictions based on the landscape of fear model. Specifically, turtles did not alter their surfacing behaviors to risk avoidance when overlap in shark–turtle core home range was high. However, in areas of high overlap with turtles, sharks exhibited modified surfacing behaviors that may enhance predation opportunity. We suggest that turtles may be an important factor in determining shark distribution, whereas for turtles, other life history trade‐offs may play a larger role in defining their habitat use. We propose that these findings are a result of both biotic and physically driven factors that independently or synergistically affect predator–prey interactions in this system. These results have implications for evolutionary biology, community ecology, and wildlife conservation. Further, given the difficulty in studying highly migratory marine species, our approach and conclusions may be applied to the study of other predator–prey systems.
Abstract.
Stringell TB, Clerveaux WV, Godley BJ, Phillips Q, Ranger S, Richardson PB, Sanghera A, Broderick AC (2015). Fisher choice may increase prevalence of green turtle fibropapillomatosis disease. Frontiers in Marine Science, 2
Broderick AC (2015). Grand challenges in marine conservation and sustainable use. Frontiers in Marine Science, 2
Stokes KL, Broderick AC, Canbolat AF, Candan O, Fuller WJ, Glen F, Levy Y, Rees AF, Rilov G, Snape RT, et al (2015). Migratory corridors and foraging hotspots: Critical habitats identified for Mediterranean green turtles.
Diversity and DistributionsAbstract:
Migratory corridors and foraging hotspots: Critical habitats identified for Mediterranean green turtles
Levels of sea turtle bycatch in the Mediterranean are thought to be unsustainable. We provide a comprehensive overview of adult green turtle (Chelonia mydas) distribution during nesting, migration and foraging phases, highlighting transitory as well as residential areas of high use to facilitate adequate protection for this long-lived, migratory species. Location: Mediterranean Sea. Methods: Thirty-four females were satellite tracked from breeding grounds in the four countries with major nesting (Cyprus, Turkey, Israel and Syria) for a total of 8521 (mean: 251) tracking days in a collaborative effort to summarize the most comprehensive set of distribution data thus far assembled for this species in the Mediterranean. Results: Ten foraging grounds are identified, with two major hotspots in Libya accounting for >50% of turtles tracked to conclusive endpoints. The coastlines of Egypt and Libya contain high densities of migrating turtles following the nesting season, particularly July-September, and likely also pre-nesting (April-June). A high-use seasonal pelagic corridor running south-west from Turkey and Cyprus to Egypt is also evident, used by >50% of all tracked turtles. Main conclusions: Bycatch levels and mortality rates for the key foraging areas and high-density seasonal pathways identified here are largely unknown and should be investigated as a priority. We recommend that the Gulf of Sirte in Libya be explored as a potential biodiversity hotspot and considered for proposal as a marine protected area (MPA). Green turtle fidelity to nesting beaches, foraging areas and migratory pathways renders them vulnerable to localized threats but enables targeted mitigation measures and protection.
Abstract.
Stokes KL, Broderick AC, Canbolat AF, Candan O, Fuller WJ, Glen F, Levy Y, Rees AF, Rilov G, Snape RT, et al (2015). Migratory corridors and foraging hotspots: Critical habitats identified for Mediterranean green turtles.
Diversity and Distributions,
21(6), 665-674.
Abstract:
Migratory corridors and foraging hotspots: Critical habitats identified for Mediterranean green turtles
Aim: Levels of sea turtle bycatch in the Mediterranean are thought to be unsustainable. We provide a comprehensive overview of adult green turtle (Chelonia mydas) distribution during nesting, migration and foraging phases, highlighting transitory as well as residential areas of high use to facilitate adequate protection for this long-lived, migratory species. Location: Mediterranean Sea. Methods: Thirty-four females were satellite tracked from breeding grounds in the four countries with major nesting (Cyprus, Turkey, Israel and Syria) for a total of 8521 (mean: 251) tracking days in a collaborative effort to summarize the most comprehensive set of distribution data thus far assembled for this species in the Mediterranean. Results: Ten foraging grounds are identified, with two major hotspots in Libya accounting for >50% of turtles tracked to conclusive endpoints. The coastlines of Egypt and Libya contain high densities of migrating turtles following the nesting season, particularly July-September, and likely also pre-nesting (April-June). A high-use seasonal pelagic corridor running south-west from Turkey and Cyprus to Egypt is also evident, used by >50% of all tracked turtles. Main conclusions: Bycatch levels and mortality rates for the key foraging areas and high-density seasonal pathways identified here are largely unknown and should be investigated as a priority. We recommend that the Gulf of Sirte in Libya be explored as a potential biodiversity hotspot and considered for proposal as a marine protected area (MPA). Green turtle fidelity to nesting beaches, foraging areas and migratory pathways renders them vulnerable to localized threats but enables targeted mitigation measures and protection.
Abstract.
Pikesley SK, Broderick AC, Cejudo D, Coyne MS, Godfrey MH, Godley BJ, Lopez P, López-Jurado LF, Elsy Merino S, Varo-Cruz N, et al (2015). Modelling the niche for a marine vertebrate: a case study incorporating behavioural plasticity, proximate threats and climate change.
Ecography,
38(8), 803-812.
Abstract:
Modelling the niche for a marine vertebrate: a case study incorporating behavioural plasticity, proximate threats and climate change
The integration of satellite telemetry, remotely sensed environmental data, and habitat/environmental modelling has provided for a growing understanding of spatial and temporal ecology of species of conservation concern. The Republic of Cape Verde comprises the only substantial rookery for the loggerhead turtle Caretta caretta in the eastern Atlantic. A size related dichotomy in adult foraging patterns has previously been revealed for adult sea turtles from this population with a proportion of adults foraging neritically, whilst the majority forage oceanically. Here we describe observed habitat use and employ ecological niche modelling to identify suitable foraging habitats for animals utilising these two distinct behavioural strategies. We also investigate how these predicted habitat niches may alter under the influence of climate change induced oceanic temperature rises. We further contextualise our niche models with fisheries catch data and knowledge of fisheries 'hotspots' to infer threat from fisheries interaction to this population, for animals employing both strategies. Our analysis revealed repeated use of coincident oceanic habitat, over multiple seasons, by all smaller loggerhead turtles, whilst larger neritic foraging turtles occupied continental shelf waters. Modelled habitat niches were spatially distinct, and under the influence of predicted sea surface temperature rises, there was further spatial divergence of suitable habitats. Analysis of fisheries catch data highlighted that the observed and modelled habitats for oceanic and neritic loggerhead turtles could extensively interact with intensive fisheries activity within oceanic and continental shelf waters of northwest Africa. We suggest that the development and enforcement of sustainable management strategies, specifically multi-national fisheries policy, may begin to address some of these issues; however, these must be flexible and adaptive to accommodate potential range shift for this species.
Abstract.
Revuelta O, León YM, Broderick AC, Feliz P, Godley BJ, Balbuena JA, Mason A, Poulton K, Savoré S, Raga JA, et al (2014). Assessing the efficacy of direct conservation interventions: clutch protection of the leatherback marine turtle in the Dominican Republic.
ORYXAbstract:
Assessing the efficacy of direct conservation interventions: clutch protection of the leatherback marine turtle in the Dominican Republic
The beaches of Jaragua National Park in the Dominican Republic are the country's last known major nesting site for the leatherback marine turtle Dermochelys coriacea. This nesting aggregation is threatened by widespread illegal egg take, and clutch relocation and artificial incubation have been carried out as protection measures since 1974. We assess the efficacy of such efforts and investigate how artificial incubation may be influencing the success and sex ratios of clutches. We compare hatching success, incubation duration and embryo mortality in in-situ clutches (n = 43) with those incubated artificially at sites in the east and west of the Park (n = 35 and n = 31, respectively). Our results show that in the west, artificial incubation significantly decreases hatching success in clutches. In the east the duration of incubation is increased, which we predict would result in an increase in the number of males from these clutches. Clutch relocation is currently the only viable conservation option for clutches on eastern beaches because of illegal egg take but action is needed to ensure that the natural sex ratio is not distorted. However, on the western beaches in situ clutch incubation seems possible through beach protection. Further community engagement and enforcement are required to improve conservation measures at eastern beaches if long-term, less sustainable intervention is to be avoided. Copyright © Fauna & Flora International 2014.
Abstract.
Stokes KL, Fuller WJ, Glen F, Godley BJ, Hodgson DJ, Rhodes KA, Snape RTE, Broderick AC (2014). Detecting green shoots of recovery: the importance of long-term individual-based monitoring of marine turtles.
Animal Conservation,
17(6), 593-602.
Abstract:
Detecting green shoots of recovery: the importance of long-term individual-based monitoring of marine turtles
Population monitoring is an essential part of evaluating the effectiveness of management interventions for conservation. Coastal breeding aggregations of marine vertebrate species that come ashore to pup or nest provide an opportunistic window of observation into otherwise widely dispersed populations. Green turtle (Chelonia mydas) nesting on the north and west coasts of northern Cyprus has been monitored consistently and exhaustively since 1993, with an intensive saturation tagging programme running at one key site for the same duration. This historically depleted nesting population is showing signs of recovery, possibly in response to nest protection approaching two decades, with increasing nest numbers and rising levels of recruitment. Strong correlation between year-to-year magnitude of nesting and the proportion of new breeders in the nesting cohort implies that recruitment of new individuals to the breeding population is an important driver of this recovery trend. Recent changes in fishing activities may be impacting the local juvenile neritic stage, however, which may hinder this potential recovery. Individuals returning to breed after two years laid fewer clutches than those returning after three or four years, demonstrating a trade-off between remigration interval and breeding output. Average clutch frequencies have remained stable around a median of three clutches a year per female despite the demographic shift towards new nesters, which typically lay fewer clutches in their first season. We show that where local fecundity has been adequately assessed, the use of average clutch frequencies can be a reliable method for deriving nester abundance from nest counts. Index sites where individual-based monitoring is possible will be important in monitoring long-term climate driven changes in reproductive rates.
Abstract.
Hawkes LA, Mcgowan A, Broderick AC, Gore S, Wheatley D, White J, Witt MJ, Godley BJ (2014). High rates of growth recorded for hawksbill sea turtles in Anegada, British Virgin Islands.
Ecology and Evolution,
4(8), 1255-1266.
Abstract:
High rates of growth recorded for hawksbill sea turtles in Anegada, British Virgin Islands
Management of species of conservation concern requires knowledge of demographic parameters, such as rates of recruitment, survival, and growth. In the Caribbean, hawksbill turtles (Eretmochelys imbricata) have been historically exploited in huge numbers to satisfy trade in their shells and meat. In the present study, we estimated growth rate of juvenile hawksbill turtles around Anegada, British Virgin Islands, using capture-mark-recapture of 59 turtles over periods of up to 649 days. Turtles were recaptured up to six times, having moved up to 5.9 km from the release location. Across all sizes, turtles grew at an average rate of 9.3 cm year-1 (range 2.3-20.3 cm year-1), and gained mass at an average of 3.9 kg year-1 (range 850 g-16.1 kg year-1). Carapace length was a significant predictor of growth rate and mass gain, but there was no relationship between either variable and sea surface temperature. These are among the fastest rates of growth reported for this species, with seven turtles growing at a rate that would increase their body size by more than half per year (51-69% increase in body length). This study also demonstrates the importance of shallow water reef systems for the developmental habitat for juvenile hawksbill turtles. Although growth rates for posthatching turtles in the pelagic, and turtles larger than 61 cm, are not known for this population, the implications of this study are that Caribbean hawksbill turtles in some areas may reach body sizes suggesting sexual maturity in less time than previously considered. In the present study, we estimated growth rate of juvenile hawksbill turtles around Anegada, British Virgin Islands, using capture-mark-recapture of 59 turtles over periods of up to 649 days. Across all sizes, turtles grew at an average rate of 9.3 cm per year (range 2.3-20.3 cm year-1), and gained mass at an average of 3.9 kg year-1 (range 850 g-16.1 kg year-1). These are among the fastest rates of growth reported for this species, with seven turtles growing at a rate that would increase their body size by more than half per year (51-69% increase in body length). © 2014 the Authors. Ecology and Evolution published by John Wiley & Sons Ltd.
Abstract.
Carreras C, Rees AF, Broderick AC, Godley BJ, Margaritoulis D (2014). Mitochondrial DNA markers of loggerhead marine turtles (<i>Caretta caretta</i>) (Testudines: Cheloniidae) nesting at Kyparissia Bay, Greece, confirm the western Greece unit and regional structuring.
SCIENTIA MARINA,
78(1), 115-124.
Author URL.
Carreras C, Rees AF, Broderick AC, Godley BJ, Margaritoulis D (2014). Mitochondrial DNA markers of loggerhead marine turtles (Caretta caretta) (Testudines: Cheloniidae) nesting at Kyparissia Bay, Greece, confirm the western Greece unit and regional structuring.
Scientia Marina,
78(1), 115-124.
Abstract:
Mitochondrial DNA markers of loggerhead marine turtles (Caretta caretta) (Testudines: Cheloniidae) nesting at Kyparissia Bay, Greece, confirm the western Greece unit and regional structuring
Genetic markers have been widely used in marine turtles to assess population structuring and origin of individuals in common feeding grounds, which are key elements for understanding their ecology and for developing conservation strategies. However, these analyses are very sensitive to missing information, especially from abundant nesting sites. Kyparissia Bay (western Greece) hosts the second largest Mediterranean nesting aggregation of the loggerhead turtle (Caretta caretta), but the genetic profile of this nesting site has not, as yet, been described using the extended version of the historically used mitochondrial DNA (mtDNA) marker. This marker was genotyped for 36 individuals nesting at Kyparissia Bay and haplotype frequencies obtained were compared with published data from other Mediterranean nesting sites. The results confirmed the connection between Kyparissia and other western Greek nesting sites and the isolation of this western Greek group from other Mediterranean nesting areas. As a consequence of this isolation, this abundant group of nesting aggregations (almost 30% of the Mediterranean stock) is not likely to significantly contribute to the recovery of other declining Mediterranean units. © 2014 CSIC.
Abstract.
Pikesley SK, Broderick AC, Cejudo D, Coyne MS, Godfrey MH, Godley BJ, Lopez P, López-Jurado LF, Elsy Merino S, Varo-Cruz N, et al (2014). Modelling the niche for a marine vertebrate: a case study incorporating behavioural plasticity, proximate threats and climate change. Ecography
Putman NF, Abreu-Grobois FA, Broderick AC, Ciofi C, Formia A, Godley BJ, Stroud S, Pelembe T, Verley P, Williams N, et al (2014). Numerical dispersal simulations and genetics help explain the origin of hawksbill sea turtles in Ascension Island.
Journal of Experimental Marine Biology and Ecology,
450, 98-108.
Abstract:
Numerical dispersal simulations and genetics help explain the origin of hawksbill sea turtles in Ascension Island
Long-distance dispersal and ontogenetic shifts in habitat use are characteristic of numerous marine species and have important ecological, evolutionary, and management implications. These processes, however, are often challenging to study due to the vast areas involved. We used genetic markers and simulations of physical transport within an ocean circulation model to gain understanding into the origin of juvenile hawksbill sea turtles (. Eretmochelys imbricata) found at Ascension Island, a foraging ground that is thousands of kilometers from known nesting beaches. Regional origin of genetic markers suggests that turtles are from Western Atlantic (86%) and Eastern Atlantic (14%) rookeries. In contrast, numerical simulations of transport by ocean currents suggest that passive dispersal from the western sources would be negligible and instead would primarily be from the East, involving rookeries along Western Africa (i.e. Principe Island) and, potentially, from as far as the Indian Ocean (e.g. Mayotte and the Seychelles). Given that genetic analysis identified the presence of a haplotype endemic to Brazilian hawksbill rookeries at Ascension, we examined the possible role of swimming behavior by juvenile hawksbills from NE Brazil on their current-borne transport to Ascension Island by performing numerical experiments in which swimming behavior was simulated for virtual particles (simulated turtles). We found that oriented swimming substantially influenced the distribution of particles, greatly altering the proportion of particles dispersing into the North Atlantic and South Atlantic. Assigning location-dependent orientation behavior to particles allowed them to reach Ascension Island, remain in favorable temperatures, encounter productive foraging areas, and return to the vicinity of their natal site. The age at first arrival to Ascension (4.5-5.5. years) of these particles corresponded well to estimates of hawksbill age based on their size. Our findings suggest that ocean currents and swimming behavior play an important role in the oceanic ecology of sea turtles and other marine animals. © 2013 Elsevier B.V.
Abstract.
Fossette S, Witt MJ, Miller P, Nalovic MA, Albareda D, Almeida AP, Broderick AC, Chacón-Chaverri D, Coyne MS, Domingo A, et al (2014). Pan-atlantic analysis of the overlap of a highly migratory species, the leatherback turtle, with pelagic longline fisheries.
Proc Biol Sci,
281(1780).
Abstract:
Pan-atlantic analysis of the overlap of a highly migratory species, the leatherback turtle, with pelagic longline fisheries.
Large oceanic migrants play important roles in ecosystems, yet many species are of conservation concern as a result of anthropogenic threats, of which incidental capture by fisheries is frequently identified. The last large populations of the leatherback turtle, Dermochelys coriacea, occur in the Atlantic Ocean, but interactions with industrial fisheries could jeopardize recent positive population trends, making bycatch mitigation a priority. Here, we perform the first pan-Atlantic analysis of spatio-temporal distribution of the leatherback turtle and ascertain overlap with longline fishing effort. Data suggest that the Atlantic probably consists of two regional management units: northern and southern (the latter including turtles breeding in South Africa). Although turtles and fisheries show highly diverse distributions, we highlight nine areas of high susceptibility to potential bycatch (four in the northern Atlantic and five in the southern/equatorial Atlantic) that are worthy of further targeted investigation and mitigation. These are reinforced by reports of leatherback bycatch at eight of these sites. International collaborative efforts are needed, especially from nations hosting regions where susceptibility to bycatch is likely to be high within their exclusive economic zone (northern Atlantic: Cape Verde, Gambia, Guinea Bissau, Mauritania, Senegal, Spain, USA and Western Sahara; southern Atlantic: Angola, Brazil, Namibia and UK) and from nations fishing in these high-susceptibility areas, including those located in international waters.
Abstract.
Author URL.
Weber SB, Weber N, Ellick J, Avery A, Frauenstein R, Godley BJ, Sim J, Williams N, Broderick AC (2014). Recovery of the South Atlantic's largest green turtle nesting population.
BIODIVERSITY AND CONSERVATION,
23(12), 3005-3018.
Author URL.
Humber F, Godley BJ, Broderick AC (2014). So excellent a fishe: a global overview of legal marine turtle fisheries.
Diversity and Distributions,
20(5), 579-590.
Abstract:
So excellent a fishe: a global overview of legal marine turtle fisheries
Aim: We provide a global assessment of the current legal direct take of marine turtles, including the scale and species breakdown at country level, and investigate the significance of legal take to marine turtle populations within the wider context of global threats. Location: World-wide. Methods: We undertook a comprehensive review of the literature (>500 publications) and contacted over 150 in-country experts to collate data for countries that permit the legal take of marine turtles (as of 1 January 2013). Current annual take for each country and species was estimated, and estimates were generated for the 1980s, 1990s and 2000s. Results: Currently, 42 countries and territories permit direct take of turtles and collectively take in excess of 42,000turtles per year, the majority of which (>80%) are green turtles Chelonia mydas (Linnaeus 1758). Ten countries account for more than 90% of legal take each year with Papua New Guinea (36.1%) and Nicaragua (22.3%) accounting for more than half of the total global take. Since 1980, we estimate that more than 2million turtles have been legally taken in these countries, with current levels
Abstract.
Humber F, Godley BJ, Broderick AC (2014). So excellent a fishe: a global overview of legal marine turtle fisheries. Diversity and Distributions
Horne CR, Fuller WJ, Godley BJ, Rhodes KA, Snape R, Stokes KL, Broderick AC (2014). The effect of thermal variance on the phenotype of marine turtle offspring.
Physiol Biochem Zool,
87(6), 796-804.
Abstract:
The effect of thermal variance on the phenotype of marine turtle offspring.
Temperature can have a profound effect on the phenotype of reptilian offspring, yet the bulk of current research considers the effects of constant incubation temperatures on offspring morphology, with few studies examining the natural thermal variance that occurs in the wild. Over two consecutive nesting seasons, we placed temperature data loggers in 57 naturally incubating clutches of loggerhead sea turtles Caretta caretta and found that greater diel thermal variance during incubation significantly reduced offspring mass, potentially reducing survival of hatchlings during their journey from the nest to offshore waters and beyond. With predicted scenarios of climate change, behavioral plasticity in nest site selection may be key for the survival of ectothermic species, particularly those with temperature-dependent sex determination.
Abstract.
Author URL.
Revuelta O, León YM, Balbuena JA, Broderick AC, Feliz P, Godley BJ, Raga JA, Tomás J (2014). The value of endangered species in protected areas at risk: the case of the leatherback turtle in the Dominican Republic.
Biodiversity and Conservation,
23(6), 1529-1539.
Abstract:
The value of endangered species in protected areas at risk: the case of the leatherback turtle in the Dominican Republic
Protected areas are considered essential elements for global biodiversity conservation. They may not necessarily result in an effective conservation of resources in developing countries due to lack of funding for management and enforcement. In addition, poor governance aligned with conflicts of economic interests related to their use can further threaten their integrity and persistence. In the Dominican Republic, the western beaches of the Jaragua National Park (JNP), a protected area which is also part of a UNESCO Biosphere Reserve, have been proposed for development using a mass-tourism model. One of the most charismatic species found in this area is the leatherback turtle (Dermochelys coriacea). In the present study, we assess hatching success, and factors affecting it, to determine the reproductive value across the area for the leatherback turtle. The main factors found driving hatching success at the study beaches are beach sector, incubation duration, date of lay and clutch size. Our results show that clutches in La Cueva (located in the buffer zone of the park) and Bahía de las Águilas (located inside the limits of the park) have an unusually high hatching success (~75 %) for this species, highlighting the importance of increasing protection efforts at these sites. We strongly recommend including La Cueva inside the limits of the JNP. © 2014 Springer Science+Business Media Dordrecht.
Abstract.
Revuelta O, León YM, Balbuena JA, Broderick AC, Feliz P, Godley BJ, Raga JA, Tomás J (2014). The value of endangered species in protected areas at risk: the case of the leatherback turtle in the Dominican Republic. Biodiversity and Conservation
Hawkes LA, McGowan A, Godley BJ, Gore S, Lange A, Tyler CR, Wheatley D, White J, Witt MJ, Broderick AC, et al (2013). Estimating sex ratios in Caribbean hawksbill turtles: Testosterone levels and climate effects.
Aquatic Biology,
18(1), 9-19.
Abstract:
Estimating sex ratios in Caribbean hawksbill turtles: Testosterone levels and climate effects
Evolutionary theory predicts that male and female offspring should be produced at a 1:1 ratio, but this may rarely be the case for species in which sex is determined during incubation by temperature, such as marine turtles. Estimates of primary sex ratio suggest that marine turtle sex ratios are highly skewed, with up to 9 females per male. We captured juvenile hawksbill turtles Eretmochelys imbricata in waters around Anegada, British Virgin Islands, a regionally important foraging aggregation, and analysed concentrations of plasma testosterone and oestradiol- 17β from 62 turtles to estimate sex ratio. There were 2.4 to 7.7 times more females than males. Testosterone concentrations correlated with sampling date and sea surface temperature (SST), with higher con centrations in the late summer when SST was highest, suggesting that assigning sex through threshold values of sex hormones must be carried out cautiously. The sex ratio in the juvenile foraging aggregation around Anegada is more male biased than at other locations, suggesting that turtles at Anegada have resilience against feminising effects of climate change. Future work should (1) integrate the relative contributions of different genetic stocks to foraging aggregations and (2) investigate the annual and seasonal cycles of sex hormones, and differences among individuals and life history stages. © Inter-Research 2013.
Abstract.
Griffin DBB, Murphy SR, Frick MG, Broderick AC, Coker JW, Coyne MS, Dodd MG, Godfrey MH, Godley BJ, Hawkes LA, et al (2013). Foraging habitats and migration corridors utilized by a recovering subpopulation of adult female loggerhead sea turtles: Implications for conservation.
Marine Biology,
160(12), 3071-3086.
Abstract:
Foraging habitats and migration corridors utilized by a recovering subpopulation of adult female loggerhead sea turtles: Implications for conservation
From 1998 to 2008, 68 adult female loggerhead sea turtles (Caretta caretta) were instrumented with platform transmitter terminals at nesting beaches in Georgia, North Carolina (NC) and South Carolina (SC) on the East Coast of the United States of America (30°48′N, 81°28′W to 33°51′N, 77°59′W). The majority of post-nesting loggerheads (N = 42, 62 %) migrated to foraging habitats in the Mid-Atlantic Bight during May-October, with a subsequent migration occurring during November-March to foraging habitats south of Cape Hatteras, NC. Nine (13 %) loggerheads initially foraged in the near-shore, coastal areas of the South Atlantic Bight, but moved to offshore habitats-closer to the Gulf Stream-during November-March, while fourteen (21 %) loggerheads remained in foraging areas along the mid-continental shelf off of the eastern coast of Florida and/or continued southward to Florida Bay and the Bahamas. The present study delineates important, post-nesting foraging habitats and migration corridors where loggerheads may interact with commercial fisheries-providing managers opportunities to develop and implement optimally effective conservation actions for the recovery of this threatened species. © 2013 Springer-Verlag Berlin Heidelberg.
Abstract.
Griffin DB, Murphy SR, Frick MG, Broderick AC, Coker JW, Coyne MS, Dodd MG, Godfrey MH, Godley BJ, Hawkes LA, et al (2013). Foraging habitats and migration corridors utilized by a recovering subpopulation of adult female loggerhead sea turtles: implications for conservation. Marine Biology, 1-16.
Fuller WJ, Godley BJ, Hodgson DJ, Reece SE, Witt MJ, Broderick AC (2013). Importance of spatio-temporal data for predicting the effects of climate change on marine turtle sex ratios.
Marine Ecology Progress Series,
488, 267-274.
Abstract:
Importance of spatio-temporal data for predicting the effects of climate change on marine turtle sex ratios
Species with temperature-dependent sex determination (TSD) are likely to be impacted by climate change. There is a paucity of data on the contemporary sex ratios of offspring produced by regional marine turtle populations. The lack of such information inhibits the ability of researchers to accurately predict how future meteorological and climate-driven changes may affect turtle populations. Moreover, these data are integral for the development of regional and global recovery plans for declining turtle populations. We estimate offspring sex ratios for the loggerhead turtle Caretta caretta at a range of beaches on the Mediterranean island of Cyprus over a 10 yr period (1997 to 2006; 40 beaches, 628 clutches, 29402 hatchlings). Based on hatchling sex determination, we found the pivotal incubation temperature (the temperature at which a 50:50 sex ratio occurs) to be 28.9°C, and the pivotal incubation duration to be 56.3 d. From the incubation durations of over 628 in situ clutches laid on different beaches, we estimate that 89% of the offspring produced from these clutches were female. There was, however, both inter-annual (74 to 95% female) and inter-beach (58-98% female) variability in mean offspring sex ratios. These findings highlight the need for wide-scale, long-term monitoring of primary sex ratios in order to accurately predict the likely impacts of climate change. Despite spatial and temporal variation in offspring sex ratios produced, male hatchlings are certainly in the minority in Cyprus. It is therefore highly likely that beaches producing males will become increasingly critical habitats for successful clutch incubation in the face of predicted rising temperatures. © Inter-Research 2013.
Abstract.
Richardson PB, Broderick AC, Coyne MS, Gore S, Gumbs JC, Pickering A, Ranger S, Witt MJ, Godley BJ (2013). Leatherback turtle conservation in the Caribbean UK overseas territories: Act local, think global?.
Marine Policy,
38, 483-490.
Abstract:
Leatherback turtle conservation in the Caribbean UK overseas territories: Act local, think global?
Leatherback turtles migrate across the jurisdictions of multiple sovereign states and present complex challenges to those responsible for their conservation. Concern for marine turtles has led to their protection under range state legislation and protective listing under a suite of multilateral environmental agreements. Evidence suggests that a distinct, reproductive sub-population of leatherback turtles is shared amongst a number of northern Caribbean range states, including the UK overseas territories (UKOTs) of Anguilla and the British Virgin Islands (BVI). The post-nesting movements of three female leatherbacks were tracked after they nested in Anguilla (n=1, tracked for 228 days) and the BVI (n=2, tracked for 12 and 13 days, respectively). These turtles used territories of multiple range states, with the leatherback tracked from Anguilla also migrating through high seas to foraging grounds in Canadian waters. In addition, a review of regional leatherback flipper tag return records helps define the range of this northern Caribbean nesting population (NCNP), which appears to be in recovery in some range states. While national legislation and conservation efforts appear to have contributed to these population recoveries, most relevant MEAs appear to have played little or no role. However, opportunities for constructive dialogue between NCNP range states exist under the Cartagena Convention the United Nations Convention on the Law of the Sea and the International Commission for the Conservation of Atlantic Tuna (ICCAT). UKOT conservation managers would, therefore, be justified in prioritising unilateral leatherback conservation action, and multilateral efforts through the Cartagena convention and regional fishery management mechanisms, over potentially costly accessions to additional MEAs.
Abstract.
Stringell TB, Calosso MC, Claydon JAB, Clerveaux W, Godley BJ, Lockhart KJ, Phillips Q, Ranger S, Richardson PB, Sanghera A, et al (2013). Marine turtle harvest in a mixed small-scale fishery: Evidence for revised management measures.
Ocean and Coastal Management,
82, 34-42.
Abstract:
Marine turtle harvest in a mixed small-scale fishery: Evidence for revised management measures
Small-scale fisheries (SSF) account for around half of the world's marine and inland fisheries, but their impact on the marine environment is usually under-estimated owing to difficulties in monitoring and regulation. Successful management of mixed SSF requires holistic approaches that sustainably exploit target species, consider non-target species and maintain fisher livelihoods. For two years, we studied the marine turtle fishery in the Turks and Caicos Islands (TCI) in the Wider Caribbean Region, where the main export fisheries are queen conch (Strombus gigas) and the spiny lobster (Panulirus argus); with fin-fish, green turtles (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata) taken for domestic consumption. We evaluate the turtle harvest in relation to the other fisheries and recommend legislation and management alternatives. We demonstrate the connectivity between multi-species fisheries and artisanal turtle capture: with increasing lobster catch-per-unit-effort (CPUE), hawksbill catch increased whilst green turtle catch decreased. With increasing conch CPUE, hawksbill catch declined and there was no demonstrable effect on green turtle catch. We estimate 176-324 green and 114-277 hawksbill turtles are harvested annually in TCI: the largest documented legal hawksbill fishery in the western Atlantic. of particular concern is the capture of adult turtles. Current legislation focuses take on larger individuals that are key to population maintenance. Considering these data we recommend the introduction of maximum size limits for both species and a closed season on hawksbill take during the lobster fishing season. Our results highlight the need to manage turtles as part of a broader approach to SSF management. © 2013 Elsevier Ltd.
Abstract.
Wright LI, Fuller WJ, Godley BJ, McGowan A, Tregenza T, Broderick AC (2013). No benefits of polyandry to female green turtles.
Behavioral Ecology,
24(4), 1022-1029.
Abstract:
No benefits of polyandry to female green turtles
Multiple paternity is extremely common in natural populations of almost all reptiles studied to date, suggesting that pay-offs from polyandrous mating systems are important in these taxonomic groups. However, strong evidence in support of direct or indirect benefits to females is scarce. We examined the relationship between polyandry and components of female reproductive success and offspring fitness in the promiscuous green turtle (Chelonia mydas), a species that exhibits highly variable levels of multiple paternity. We did not detect any clear fitness benefits to polyandrous females in this study, and we discuss the potential of sexual conflict to influence female mating patterns in marine turtles. We show that polyandrous females produce significantly smaller clutches than monandrous females, highlighting a potential cost to polyandry in green turtles. Furthermore, multiple paternity was more common in returning females (recorded breeding in a previous season) than in females nesting for the first time at our study site, possibly reflecting increased encounter rates with males or sperm storage across breeding seasons. Our results reveal potentially complex influences of female traits, environment, and mating strategy on components of reproductive success, and we discuss the challenges associated with unraveling the costs and benefits of multiple mating in natural populations. © 2013 the Author. Published by Oxford University Press on behalf of the International Society for Behavioral Ecology. All rights reserved.
Abstract.
Richardson PB, Broderick AC, Coyne MS, Ekanayake L, Kapurusinghe T, Premakumara C, Ranger S, Saman MM, Witt MJ, Godley BJ, et al (2013). Satellite telemetry reveals behavioural plasticity in a green turtle population nesting in Sri Lanka.
Marine Biology,
160(6), 1415-1426.
Abstract:
Satellite telemetry reveals behavioural plasticity in a green turtle population nesting in Sri Lanka
Satellite transmitters were deployed on ten green turtles (Chelonia mydas) nesting in Rekawa Sanctuary (RS-80.851°E 6.045°N), Sri Lanka, during 2006 and 2007 to determine inter-nesting and migratory behaviours and foraging habitats. Nine turtles subsequently nested at RS and demonstrated two inter-nesting strategies linked to the location of their residence sites. Three turtles used local shallow coastal sites within 60 km of RS during some or all of their inter-nesting periods and then returned to and settled at these sites on completion of their breeding seasons. In contrast, five individuals spent inter-nesting periods proximate to RS and then migrated to and settled at distant (>350 km) shallow coastal residence sites. Another turtle also spent inter-nesting periods proximate to RS and then migrated to a distant oceanic atoll and made forays into oceanic waters for 42 days before transmissions ceased. This behavioural plasticity informs conservation management beyond protection at the nesting beach. © 2013 Springer-Verlag Berlin Heidelberg.
Abstract.
Richardson PB, Broderick AC, Coyne MS, Ekanayake L, Kapurusinghe T, Premakumara C, Ranger S, Saman MM, Witt MJ, Godley BJ, et al (2013). Satellite telemetry reveals behavioural plasticity in a green turtle population nesting in Sri Lanka. Marine Biology, 1-12.
Snape RTE, Beton D, Broderick AC, Çiçek BA, Fuller WJ, Özden O, Godley BJ (2013). Strand monitoring and anthropological surveys provide insight into marine turtle bycatch in small-scale fisheries of the Eastern Mediterranean.
Chelonian Conservation and Biology,
12(1), 44-55.
Abstract:
Strand monitoring and anthropological surveys provide insight into marine turtle bycatch in small-scale fisheries of the Eastern Mediterranean
It has become widely recognized that a large gap exists in the global knowledge of fisheries due to the continued oversight of the small-scale sector. For populations of marine turtles restricted to the eastern Mediterranean, bycatch in small-scale fisheries is a concern. By using North Cyprus as a case study for the region, we used anthropological methods to estimate the magnitude of marine turtle bycatch, while presenting novel information on the marine turtle life stages using the coast and profiling the fishery itself. Our analyses suggest that as many as 1000 turtles may be caught annually by this fishery with an estimated mortality rate of 60%. Trammel nets were the main cause of marine turtle bycatch. Strandings coincided with setting of trammel nets that target siganids (Siganus luridus and Siganus rivulatus) and the majority of bycatch registered by fishers were caught in these gear types. We demonstrate a relatively simple approach to evaluating marine turtle bycatch, providing information that will allow local authorities and conservation groups to direct further research and possible mitigation measures. © 2013 Chelonian Research Foundation.
Abstract.
Weber N, Weber SB, Godley BJ, Ellick J, Witt M, Broderick AC (2013). Telemetry as a tool for improving estimates of marine turtle abundance.
Biological Conservation,
167, 90-96.
Abstract:
Telemetry as a tool for improving estimates of marine turtle abundance
Accurate estimates of abundance are fundamental to the conservation of threatened species, but are often difficult to obtain directly. Population size assessments of marine turtles are often based on counts of nests, which are then related to abundance using the mean number of clutches laid by individuals within a season. Due to low re-encounter probabilities, clutch frequency has proven difficult to estimate reliably, particularly for large populations that make a major contribution to global stock assessments. We use a combination of VHF radio-telemetry and Argos-linked Fastloc™ GPS devices to improve clutch frequency estimates for one of the world's largest green turtle rookeries at Ascension Island. Females fitted with VHF tags at the start of the season (. n=. 40) were re-encountered with a probability of 85% and laid a minimum average of 5.8 clutches. Three of these turtles were fitted with VHF and GPS devices and using the data collected by the latter, were found to lay an average of 6.3 clutches. GPS-telemetry detected emergences observed using radio-telemetry, and confirmed that some radio-tagged turtles laid again after their last observed emergence. Correcting for missed nesting events yielded a mean clutch frequency of 6.3, more than doubling the previous estimate of 3.0 for this population. Applying this revised assessment to annual nest counts reduces the estimated size of this population by 52%. Conventional tagging approaches may considerably underestimate annual fecundity of turtles, resulting in inflated population size estimates. We call for urgent reassessment of baseline abundance values for regionally important populations. © 2013 Elsevier Ltd.
Abstract.
Witt MJ, Sheehan EV, Bearhop S, Broderick AC, Conley DC, Cotterell SP, Crow E, Grecian WJ, Halsband C, Hodgson DJ, et al (2012). Assessing wave energy effects on biodiversity: the Wave Hub experience. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 370(1959), 502-529.
Witt MJ, Sheehan EV, Bearhop S, Broderick AC, Conley DC, Cotterell SP, Crow E, Grecian WJ, Halsband C, Hodgson DJ, et al (2012). Assessing wave energy effects on biodiversity: the Wave Hub experience.
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences,
370(1959), 502-529.
Abstract:
Assessing wave energy effects on biodiversity: the Wave Hub experience
Marine renewable energy installations harnessing energy from wind, wave and tidal resources are likely to become a large part of the future energy mix worldwide. The potential to gather energy from waves has recently seen increasing interest, with pilot developments in several nations. Although technology to harness wave energy lags behind that of wind and tidal generation, it has the potential to contribute significantly to energy production. As wave energy technology matures and becomes more widespread, it is likely to result in further transformation of our coastal seas. Such changes are accompanied by uncertainty regarding their impacts on biodiversity. To date, impacts have not been assessed, as wave energy converters have yet to be fully developed. Therefore, there is a pressing need to build a framework of understanding regarding the potential impacts of these technologies, underpinned by methodologies that are transferable and scalable across sites to facilitate formal meta-analysis. We first review the potential positive and negative effects of wave energy generation, and then, with specific reference to our work at the Wave Hub (a wave energy test site in southwest England, UK), we set out the methodological approaches needed to assess possible effects of wave energy on biodiversity. We highlight the need for national and international research clusters to accelerate the implementation of wave energy, within a coherent understanding of potential effects-both positive and negative. © 2011 the Royal Society.
Abstract.
Rees AF, Al-Kiyumi A, Broderick AC, Papathanasopoulou N, Godley BJ (2012). Conservation related insights into the behaviour of the olive ridley sea turtle Lepidochelys olivacea nesting in Oman.
Marine Ecology Progress Series,
450, 195-205.
Abstract:
Conservation related insights into the behaviour of the olive ridley sea turtle Lepidochelys olivacea nesting in Oman
We followed the movements of 9 adult female olive ridley turtles Lepidochelys olivacea after nesting on Masirah Island, Oman, using satellite tracking. Their post-breeding migrations ranged from 85 to 796 km. Three individuals travelled north to foraging grounds in Pakistan, Iran and the United Arab Emirates. The other 6 turtles remained in Omani seas for extended periods (mean ± SD = 171.3 ± 109.4 d; range = 40 to 310 d). These locally resident turtles experienced biannual cooling of sea temperatures due to the effect of the west Arabian Sea upwelling which was not experienced by those that migrated to the north. Indications of disparity in turtle size between foraging locations are identified for the first time in this species. The majority of turtles (8) settled in coastal areas of water depth
Abstract.
Rees AF, Al-Kiyumi A, Broderick AC, Papathanasopoulou N, Godley BJ (2012). Each to their own: Inter-specific differences in migrations of Masirah Island turtles.
Chelonian Conservation and Biology,
11(2), 243-248.
Abstract:
Each to their own: Inter-specific differences in migrations of Masirah Island turtles
We tracked two adult female green turtles (Chelonia mydas) from their nesting location on Masirah Island, Oman (lat 20.441°N, long 58.843°E) into the Red Sea. Comparing these tracks with published movements of nesting loggerhead (Caretta caretta) and olive ridley (Lepidochelys olivacea) turtles, also tracked from Masirah, revealed remarkably different inter-specific patterns of post-nesting dispersal. High-capacity artisanal fisheries, with undescribed levels of sea turtle bycatch, exist within the region, making introduction of effective conservation measures difficult. © 2012 Chelonian Research Foundation.
Abstract.
Scott R, Hodgson DJ, Witt MJ, Coyne MS, Blumenthal JM, Broderick AC, Richardson PB, Rees AF, Godley BJ, Coyne MS, et al (2012). Global analysis of satellite tracking data shows that adult green turtles are significantly aggregated in Marine Protected Areas.
Global Ecology and BiogeographyAbstract:
Global analysis of satellite tracking data shows that adult green turtles are significantly aggregated in Marine Protected Areas
Aim Tracking technologies are often proposed as a method to elucidate the complex migratory life histories of migratory marine vertebrates, allowing spatially explicit threats to be identified and mitigated. We conducted a global analysis of foraging areas of adult green turtles (Chelonia mydas) subject to satellite tracking (n= 145) and the conservation designation of these areas according to International Union for Conservation of Nature criteria. Location the green turtle has a largely circumtropical distribution, with adults migrating up to thousands of kilometres between nesting beaches and foraging areas, typically in neritic seagrass or algal beds. Methods We undertook an assessment of satellite tracking projects that followed the movements of green turtles in tropical and subtropical habitats. This approach was facilitated by the use of the Satellite Tracking and Analysis Tool () and the integration of publicly available data on Marine Protected Areas (MPAs). Results We show that turtles aggregate in designated MPAs far more than would be expected by chance when considered globally (35% of all turtles were located within MPAs) or separately by ocean basin (Atlantic 67%, Indian 34%, Mediterranean 19%, Pacific 16%). Furthermore, we show that the size, level of protection and time of establishment of MPAs affects the likelihood of MPAs containing foraging turtles, highlighting the importance of large, well-established reserves. Main conclusions Our findings constitute compelling evidence of the world-wide effectiveness of extant MPAs in circumscribing important foraging habitats for a marine megavertebrate. © 2012 Blackwell Publishing Ltd.
Abstract.
Scott R, Hodgson DJ, Witt MJ, Coyne MS, Adnyana W, Blumenthal JM, Broderick AC, Canbolat AF, Catry P, Ciccione S, et al (2012). Global analysis of satellite tracking data shows that adult green turtles are significantly aggregated in Marine Protected Areas.
Global Ecology and Biogeography,
21(11), 1053-1061.
Abstract:
Global analysis of satellite tracking data shows that adult green turtles are significantly aggregated in Marine Protected Areas
Aim Tracking technologies are often proposed as a method to elucidate the complex migratory life histories of migratory marine vertebrates, allowing spatially explicit threats to be identified and mitigated. We conducted a global analysis of foraging areas of adult green turtles (Chelonia mydas) subject to satellite tracking (n= 145) and the conservation designation of these areas according to International Union for Conservation of Nature criteria. Location the green turtle has a largely circumtropical distribution, with adults migrating up to thousands of kilometres between nesting beaches and foraging areas, typically in neritic seagrass or algal beds. Methods We undertook an assessment of satellite tracking projects that followed the movements of green turtles in tropical and subtropical habitats. This approach was facilitated by the use of the Satellite Tracking and Analysis Tool (http://www.seaturtle.org) and the integration of publicly available data on Marine Protected Areas (MPAs). Results We show that turtles aggregate in designated MPAs far more than would be expected by chance when considered globally (35% of all turtles were located within MPAs) or separately by ocean basin (Atlantic 67%, Indian 34%, Mediterranean 19%, Pacific 16%). Furthermore, we show that the size, level of protection and time of establishment of MPAs affects the likelihood of MPAs containing foraging turtles, highlighting the importance of large, well-established reserves. Main conclusions Our findings constitute compelling evidence of the world-wide effectiveness of extant MPAs in circumscribing important foraging habitats for a marine megavertebrate. © 2012 Blackwell Publishing Ltd.
Abstract.
Richardson PB, Broderick AC, Coyne MS, Gore S, Gumbs JC, Pickering A, Ranger S, Witt MJ, Godley BJ (2012). Leatherback turtle conservation in the Caribbean UK overseas territories: Act local, think global?. Marine Policy
Casale P, Broderick AC, Freggi D, Mencacci R, Fuller WJ, Godley BJ, Luschi P (2012). Long-term residence of juvenile loggerhead turtles to foraging grounds: a potential conservation hotspot in the Mediterranean. Aquatic Conservation: Marine and Freshwater Ecosystems
Casale P, Broderick AC, Freggi D, Mencacci R, Fuller WJ, Godley BJ, Luschi P (2012). Long-term residence of juvenile loggerhead turtles to foraging grounds: a potential conservation hotspot in the Mediterranean.
Aquatic Conservation: Marine and Freshwater Ecosystems,
22(2), 144-154.
Abstract:
Long-term residence of juvenile loggerhead turtles to foraging grounds: a potential conservation hotspot in the Mediterranean
Identifying highly frequented areas is a priority for sea turtle conservation. Although juveniles represent the bulk of the population, a minority of studies have investigated their movement patterns. Six large juvenile loggerhead turtles that were found and released in an important foraging ground in the Mediterranean, the Tunisian continental shelf were tracked. Tracking data were obtained via satellite for periods ranging from 120 to 225days and allowed the identification of high use areas. All turtles generally performed apparently non-directed, wandering movements in waters with a wide range of seafloor depths. They showed clear residential behaviour to the region with no evident seasonal pattern. Core areas of residence were in the neritic zone or on the edge of the continental shelf, largely overlapping among individuals, and were much smaller than residential oceanic areas reported elsewhere. When integrated into current knowledge, these results suggest an ecological-behavioural model of a gradual shift from a pelagic-vagile to a benthic-sedentary life style with progressive reduction of home ranges. They also highlight an area of the continental shelf and offshore waters as potential core foraging ground for large juvenile loggerhead turtles in the Mediterranean informing future spatial management for loggerhead turtles. © 2012 John Wiley & Sons, Ltd.
Abstract.
Leeney RH, Witt MJ, Broderick AC, Buchanan J, Jarvis DS, Richardson PB, Godley BJ (2012). Marine megavertebrates of Cornwall and the Isles of Scilly: Relative abundance and distribution.
Journal of the Marine Biological Association of the United Kingdom,
92(8), 1823-1833.
Abstract:
Marine megavertebrates of Cornwall and the Isles of Scilly: Relative abundance and distribution
We document patterns of distribution and relative abundance of marine megavertebrate fauna around Cornwall and the Isles of Scilly from a combination of aerial and boat-based surveying. Between January 2006 and November 2007, 20 aerial surveys were undertaken, comprising over 40 hours of on-effort flying time. In April to October of these years, 27 effort-corrected ferry surveys were also conducted from a passenger ferry travelling between Cornwall and the Isles of Scilly. Opportunistic sightings were also logged by the crew members of the ferry and another vessel travelling regularly along the same route on 155 days. Ten megavertebrate species were sighted: basking sharks Cetorhinus maximus, sunfish Mola mola, common dolphins Delphinus delphis, harbour porpoise Phocoena phocoena, grey seals Halichoerus grypus, Risso's dolphins Grampus griseus, bottlenose dolphins Tursiops truncatus, minke whales Balaenoptera acutorostrata, long-finned pilot whales Globicephala melas and killer whale Orcinus orca. During aerial surveys, 206 sighting events of seven species were made, compared with 145 sighting events of eight species during ferry surveys and 293 sighting events of 10 species from opportunistic ship-board data collection efforts. Seasonal and spatial patterns in species occurrence were evident. Basking sharks were the most commonly-sighted species in the region and were relatively abundant throughout the estimated 5 km-wide strip of coastal waters covered by the aerial surveys, during spring and summer. Ferry surveys and opportunistic vessel-based sightings data confirmed that the distribution of surface-feeding aggregations of this species was largely around the coasts. Despite the limited scope of this study, it has provided valuable baseline data, and possible insights into the marine biodiversity of the region. © 2012 Marine Biological Association of the United Kingdom.
Abstract.
Hawkes LA, Tomás J, Revuelta O, León YM, Blumenthal JM, Broderick AC, Fish M, Raga JA, Witt MJ, Godley BJ, et al (2012). Migratory patterns in hawksbill turtles described by satellite tracking.
Marine Ecology Progress Series,
461, 223-232.
Abstract:
Migratory patterns in hawksbill turtles described by satellite tracking
The advent of telemetry has improved knowledge of the spatio-temporal distribution of marine species of conservation concern. Among the sea turtles, the movements of the hawksbill turtle Eretmochelys imbricata are among the least well described. We tracked 10 adult female hawksbill turtles by satellite after nesting in the Dominican Republic (DR) and describe a dichotomy in patterns of movement: some (n = 2) turtles remained in the DR, while others migrated to waters off Honduras and Nicaragua (n = 5) and the Bahamas (n = 1). Transmitters on 2 turtles failed during migration, before they reached their final foraging grounds. We present results from long tracking durations for 3 turtles, including 3 entire remigration intervals, high-lighting foraging ground and nest-site fidelity. Threats to hawksbill turtles are not well documented for Nicaragua or neighbouring Honduras and represent a major information gap. We suggest that directing conservation efforts to regionally important foraging areas, such as those in Nicaragua, and strengthening national conservation in each nation with significant hawksbill nesting offers a clear way forward for the conservation of hawksbill turtles in the region. © Inter-Research 2012 · www.int-res.com.
Abstract.
Wright LI, Fuller WJ, Godley BJ, McGowan A, Tregenza T, Broderick AC (2012). Reconstruction of paternal genotypes over multiple breeding seasons reveals male green turtles do not breed annually.
Molecular Ecology,
21(14), 3625-3635.
Abstract:
Reconstruction of paternal genotypes over multiple breeding seasons reveals male green turtles do not breed annually
For species of conservation concern, knowledge of key life-history and demographic components, such as the number and sex ratio of breeding adults, is essential for accurate assessments of population viability. Species with temperature-dependent sex determination can produce heavily biased primary sex ratios, and there is concern that adult sex ratios may be similarly skewed or will become so as a result of climate warming. Prediction and mitigation of such impacts are difficult when life-history information is lacking. In marine turtles, owing to the difficultly in observing males at sea, the breeding interval of males is unknown. It has been suggested that male breeding periodicity may be shorter than that of females, which could help to compensate for generally female-biased sex ratios. Here we outline how the use of molecular-based paternity analysis has allowed us, for the first time, to assess the breeding interval of male marine turtles across multiple breeding seasons. In our study rookery of green turtles (Chelonia mydas), 97% of males were assigned offspring in only one breeding season within the 3-year study period, strongly suggesting that male breeding intervals are frequently longer than 1 year at this site. Our results also reveal a sex ratio of breeding adults of at least 1.3 males to each female. This study illustrates the utility of molecular-based parentage inference using reconstruction of parental genotypes as a method for monitoring the number and sex ratio of breeders in species where direct observations or capture are difficult. © 2012 Blackwell Publishing Ltd.
Abstract.
Wright LI, Fuller WJ, Godley BJ, McGowan A, Tregenza T, Broderick AC (2012). Reconstruction of paternal genotypes over multiple breeding seasons reveals male green turtles do not breed annually.
Mol Ecol,
21(14), 3625-3635.
Abstract:
Reconstruction of paternal genotypes over multiple breeding seasons reveals male green turtles do not breed annually.
For species of conservation concern, knowledge of key life-history and demographic components, such as the number and sex ratio of breeding adults, is essential for accurate assessments of population viability. Species with temperature-dependent sex determination can produce heavily biased primary sex ratios, and there is concern that adult sex ratios may be similarly skewed or will become so as a result of climate warming. Prediction and mitigation of such impacts are difficult when life-history information is lacking. In marine turtles, owing to the difficultly in observing males at sea, the breeding interval of males is unknown. It has been suggested that male breeding periodicity may be shorter than that of females, which could help to compensate for generally female-biased sex ratios. Here we outline how the use of molecular-based paternity analysis has allowed us, for the first time, to assess the breeding interval of male marine turtles across multiple breeding seasons. In our study rookery of green turtles (Chelonia mydas), 97% of males were assigned offspring in only one breeding season within the 3-year study period, strongly suggesting that male breeding intervals are frequently longer than 1year at this site. Our results also reveal a sex ratio of breeding adults of at least 1.3 males to each female. This study illustrates the utility of molecular-based parentage inference using reconstruction of parental genotypes as a method for monitoring the number and sex ratio of breeders in species where direct observations or capture are difficult.
Abstract.
Author URL.
Wright LI, Stokes KL, Fuller WJ, Godley BJ, McGowan A, Snape R, Tregenza T, Broderick AC (2012). Turtle mating patterns buffer against disruptive effects of climate change.
Proc Biol Sci,
279(1736), 2122-2127.
Abstract:
Turtle mating patterns buffer against disruptive effects of climate change.
For organisms with temperature-dependent sex determination (TSD), skewed offspring sex ratios are common. However, climate warming poses the unique threat of producing extreme sex ratio biases that could ultimately lead to population extinctions. In marine turtles, highly female-skewed hatchling sex ratios already occur and predicted increases in global temperatures are expected to exacerbate this trend, unless species can adapt. However, it is not known whether offspring sex ratios persist into adulthood, or whether variation in male mating success intensifies the impact of a shortage of males on effective population size. Here, we use parentage analysis to show that in a rookery of the endangered green turtle (Chelonia mydas), despite an offspring sex ratio of 95 per cent females, there were at least 1.4 reproductive males to every breeding female. Our results suggest that male reproductive intervals may be shorter than the 2-4 years typical for females, and/or that males move between aggregations of receptive females, an inference supported by our satellite tracking, which shows that male turtles may visit multiple rookeries. We suggest that male mating patterns have the potential to buffer the disruptive effects of climate change on marine turtle populations, many of which are already seriously threatened.
Abstract.
Author URL.
Weber SB, Broderick AC, Groothuis TGG, Ellick J, Godley BJ, Blount JD (2011). Fine-scale thermal adaptation in a green turtle nesting population.
Proceedings of the Royal Society of London B: Biological SciencesAbstract:
Fine-scale thermal adaptation in a green turtle nesting population
The effect of climate warming on the reproductive success of ectothermic animals is currently a subject of major conservation concern. However, for many threatened species we still know surprisingly little about the extent of naturally-occurring adaptive variation in heat tolerance. Here, we show that the thermal tolerances of green turtle (Chelonia mydas) embryos in a single, island-breeding population have diverged in response to the contrasting incubation temperatures of nesting beaches just a few kilometres apart. In natural nests and in a common-garden rearing experiment, the offspring of females nesting on a naturally hot (black sand) beach survived better and grew larger at hot incubation temperatures compared to the offspring of females nesting on a cooler (pale sand) beach nearby. These differences were due to shallower thermal reaction norms in the hot beach population, rather than a shift in thermal optima, and were not related to maternal provisioning of resources into eggs. Our results suggest that marine turtle nesting behaviour can drive adaptive differentiation at surprisingly fine spatial scales, and have important implications for how we define conservation units for protection. In particular, previous studies may have underestimated the extent of adaptive structuring in marine turtle populations which may significantly affect their capacity to respond to environmental change.
Abstract.
Hawkes LA, Witt MJ, Broderick AC, Coker JW, Coyne MS, Dodd M, Frick MG, Godfrey MH, Griffin DB, Murphy SR, et al (2011). Home on the range: Spatial ecology of loggerhead turtles in Atlantic waters of the USA.
Diversity and Distributions,
17(4), 624-640.
Abstract:
Home on the range: Spatial ecology of loggerhead turtles in Atlantic waters of the USA
Aim Although satellite tracking has yielded much information regarding the migrations and habitat use of threatened marine species, relatively little has been published about the environmental niche for loggerhead sea turtles Caretta caretta in north-west Atlantic waters. Location North Carolina, South Carolina and Georgia, USA. Methods We tracked 68 adult female turtles between 1998 and 2008, one of the largest sample sizes to date, for 372.2±210.4days (mean±SD). Results We identified two strategies: (1) 'seasonal' migrations between summer and winter coastal areas (n=47), although some turtles made oceanic excursions (n=4) and (2) occupation of more southerly 'year-round' ranges (n=18). Seasonal turtles occupied summer home ranges of 645.1km2 (median, n = 42; using α-hulls) predominantly north of 35° latitude and winter home ranges of 339.0km2 (n=24) in a relatively small area on the narrow shelf off North Carolina. We tracked some of these turtles through successive summer (n=8) and winter (n=3) seasons, showing inter-annual home range repeatability to within 14.5km of summer areas and 10.3km of winter areas. For year-round turtles, home ranges were 1889.9km2. Turtles should be tracked for at least 80days to reliably estimate the home range size in seasonal habitats. The equivalent minimum duration for 'year-round' turtles is more complex to derive. We define an environmental envelope of the distribution of North American loggerhead turtles: warm waters (between 18.2 and 29.2°C) on the coastal shelf (in depths of 3.0-89.0m). Main conclusions Our findings show that adult female loggerhead turtles show predictable, repeatable home range behaviour and do not generally leave waters of the USA, nor the continental shelf (
Abstract.
Weber SB, Blount JD, Godley BJ, Witt MJ, Broderick AC (2011). Rate of egg maturation in marine turtles exhibits 'universal temperature dependence'.
J Anim Ecol,
80(5), 1034-1041.
Abstract:
Rate of egg maturation in marine turtles exhibits 'universal temperature dependence'.
1. The metabolic theory of ecology (MTE) predicts that, after correcting for body mass variation among organisms, the rates of most biological processes will vary as a universal function of temperature. However, empirical support for 'universal temperature dependence' (UTD) is currently equivocal and based on studies of a limited number of traits. 2. In many ectothermic animals, the rate at which females produce mature eggs is temperature dependent and may be an important factor in determining the costs of reproduction. 3. We tested whether the rate of egg maturation in marine turtles varies with environmental temperature as predicted by MTE, using the time separating successive clutches of individual females to estimate the rate at which eggs are formed. We also assessed the phenotypic contribution to this rate, by using radio telemetry to make repeated measurements of interclutch intervals for individual green turtles (Chelonia mydas). 4. Rates of egg maturation increased with seasonally increasing water temperatures in radio-tracked green turtles, but were not repeatable for individual females, and did not vary according to maternal body size or reproductive investment (number and size of eggs produced). 5. Using a collated data set from several different populations and species of marine turtles, we then show that a single relationship with water temperature explains most of the variation in egg maturation rates, with a slope that is statistically indistinguishable from the UTD predicted by MTE. However, several alternative statistical models also described the relationship between temperature and egg maturation rates equally parsimoniously. 6. Our results offer novel support for the MTE's predicted UTD of biological rates, although the underlying mechanisms require further study. The strong temperature dependence of egg maturation combined with the apparently weak phenotypic contribution to this rate has interesting behavioural implications in ectothermic animals. We suggest that maternal thermoregulatory behaviour in marine turtles, and many other reptiles, is consistent with a strategy of adaptively increasing body temperatures to accelerate egg maturation.
Abstract.
Author URL.
Witt MJ, Godley BJ, Broderick AC, Coyne MS (2011). Tracking leatherback turtles from the world's largest rookery: assessing threats across the South Atlantic.
Proceedings of the Royal Society BAbstract:
Tracking leatherback turtles from the world's largest rookery: assessing threats across the South Atlantic
Despite extensive work carried out on leatherback turtles (Dermochelys coriacea) in the North Atlantic and Indo-Pacific, very little is known of the at-sea distribution of this species in the South Atlantic, where the world's largest population nests in Gabon (central Africa). This paucity of data is of marked concern given the pace of industrialization in fisheries with demonstrable marine turtle bycatch in African/Latin American waters. We tracked the movements of 25 adult female leatherback turtles obtaining a range of fundamental and applied insights, including indications for methodological advancement. Individuals could be assigned to one of three dispersal strategies, moving to (i) habitats of the equatorial Atlantic, (ii) temperate habitats off South America or (iii) temperate habitats off southern Africa. While occupying regions with high surface chlorophyll concentrations, these strategies exposed turtles to some of the world's highest levels of longline fishing effort, in addition to areas with coastal gillnet fisheries. Satellite tracking highlighted that at least 11 nations should be involved in the conservation of this species in addition to those with distant fishing fleets. The majority of tracking days were, however, spent in the high seas, where effective implementation of conservation efforts is complex to achieve.
Abstract.
Humber F, Godley BJ, Ramahery V, Broderick AC (2011). Using community members to assess artisanal fisheries: the marine turtle fishery in Madagascar. Animal Conservation(14), 175-185.
Leeney RH, Broderick AC, Mills C, Sayer S, Witt MJ, Godley BJ (2010). Abundance, distribution and haul-out behaviour of grey seals (Halichoerus grypus) in Cornwall and the Isles of Scilly, UK.
Journal of the Marine Biological Association of the United Kingdom,
90(5), 1033-1040.
Abstract:
Abundance, distribution and haul-out behaviour of grey seals (Halichoerus grypus) in Cornwall and the Isles of Scilly, UK
This study investigated the phenology, patterns of haul-out habitat use and distribution of the grey seal around Cornwall and the Isles of Scilly. A full census of the coast was carried out by boat over 4 days, in order to make a full count of seals hauled out and close to the coast, and to document all haul-out sites. Regular land-based surveys were made of three haul-out sites in Cornwall, to investigate the effects of spatial, temporal and environmental factors on seal haul-out behaviour. Data from 2004 to 2007 were analysed to describe long-term temporal variation in seal abundance at two haul-out sites. A total of 592 sightings were made along the coast of Cornwall and the Isles of Scilly over the four-day census period; 476 of these sightings (80.4%) were recorded at six main haul-out sites. The highest proportion of seals was observed at three haul-out areas on the Isles of Scilly. In Cornwall, seals were observed in higher numbers on the north coast, where the three largest mainland haul-out sites were documented, than on the south coast. At one key haul-out site in Cornwall, a distinct seasonal pattern was evident in data collected between 2004 and 2007, with higher numbers of seals present during the moulting and breeding seasons than over the summer months. There was considerable inter-annual variability in peak seal abundance, during the moulting season, at this site. There was no significant variation in haul-out behaviour with tidal state at this site, although haul-out counts were generally highest at mid-ebb tides. Data on seal abundance, distribution and haul-out behaviour may aid the designation of Special Areas of Conservation for the protection of grey seals in Cornwall and the Isles of Scilly. © 2010 Marine Biological Association of the United Kingdom.
Abstract.
Witt MJ, Åkesson S, Broderick AC, Coyne MS, Ellick J, Formia A, Hays GC, Luschi P, Stroud S, Godley BJ, et al (2010). Assessing accuracy and utility of satellite-tracking data using Argos-linked Fastloc-GPS. Animal Behaviour, 80(3), 571-581.
Rees AF, Al Saady S, Broderick AC, Coyne MS, Papathanasopoulou N, Godley BJ (2010). Behavioural polymorphism in one of the world's largest populations of loggerhead sea turtles Caretta caretta.
Marine Ecology Progress Series,
418, 201-212.
Abstract:
Behavioural polymorphism in one of the world's largest populations of loggerhead sea turtles Caretta caretta
To aid management and conservation of widely distributed marine vertebrate species, it is necessary to have a knowledge and understanding of their spatial ecology. We tracked 10 adult female loggerhead turtles Caretta caretta from Masirah Island, Sultanate of Oman, which hosts one of the world's largest breeding aggregations. Transmitters were specifically deployed early in the nesting season to enable tracking throughout the internesting and post-nesting habitats. Turtles displayed a dichotomy in behaviour during the internesting period, with 6 remaining close to Masirah Island and the others undertaking circuitous oceanic loops, hundreds of kilometres in length. This behaviour did not appear to be related to body size. Tracking-derived minimum clutch frequency was on average (± SD) 4.8 ±1.2 nests (n = 8 ind.). Post-nesting migrations revealed a propensity towards long-term utilisation of oceanic habitats in the region between Socotra Island (Yemen) and the mainland of Yemen/Oman, with 76 ± 15.4% of time spent in oceanic habitat (n = 8 ind.). The spatial footprint of our tracked turtles was found to be far less than that of a similar number of turtles that were tagged later in the same season (from a separate unpublished study) and from long-distance returns of flipper tags. The spatial and temporal sub-structuring of the population highlights the need for more comprehensive tracking projects, with deployments across the breeding season in multiple years, in order to obtain reliable estimations of high-use foraging habitats of widely dispersed marine vertebrates. Variation in behaviour patterns suggests the need for diverse conservation measures. © Inter-Research 2010.
Abstract.
Hamann M, Godfrey MH, Seminoff JA, Arthur K, Barata PCR, Bjorndal KA, Bolten AB, Broderick AC, Campbell LM, Carreras C, et al (2010). Global research priorities for sea turtles: Informing management and conservation in the 21st century.
Endangered Species Research,
11(3), 245-269.
Abstract:
Global research priorities for sea turtles: Informing management and conservation in the 21st century
Over the past 3 decades, the status of sea turtles and the need for their protection to aid population recovery have increasingly captured the interest of government agencies, non-governmental organisations (NGOs) and the general public worldwide. This interest has been matched by increased research attention, focusing on a wide variety of topics relating to sea turtle biology and ecology, together with the interrelations of sea turtles with the physical and natural environments. Although sea turtles have been better studied than most other marine fauna, management actions and their evaluation are often hindered by the lack of data on turtle biology, human-turtle interactions, turtle population status and threats. In an effort to inform effective sea turtle conservation a list of priority research questions was assembled based on the opinions of 35 sea turtle researchers from 13 nations working in fields related to turtle biology and/or conservation. The combined experience of the contributing researchers spanned the globe as well as many relevant disciplines involved in conservation research. An initial list of more than 200 questions gathered from respondents was condensed into 20 metaquestions and classified under 5 categories: reproductive biology, biogeography, population ecology, threats and conservation strategies. © Inter-Research 2010.
Abstract.
Witt MJ, McGowan A, Blumenthal JM, Broderick AC, Gore S, Wheatley D, White J, Godley BJ (2010). Inferring vertical and horizontal movements of juvenile marine turtles from time-depth recorders.
AQUATIC BIOLOGY,
8(2), 169-177.
Author URL.
Bell CD, Blumenthal JM, Broderick AC, Godley BJ (2010). Investigating potential for depensation in marine turtles: How low can you Go?: Contributed paper.
Conservation Biology,
24(1), 226-235.
Abstract:
Investigating potential for depensation in marine turtles: How low can you Go?: Contributed paper
Where mechanisms inherent within the biology of a species affect individual fitness at low density, demographic-scale depensation may occur, hastening further decline and leading ultimately to population extirpation and species extinction. Reduction in fertility at low population densities has been identified in marine and terrestrial species. Using data on hatch success and hatchling-emergence success as proxies for fertilization success, we conducted a global meta-analysis of data from breeding aggregations of green turtles (Chelonia mydas) and loggerhead turtles (Caretta caretta). We found that there has been no reduction in fertility in small nesting aggregations in either of these species worldwide. We considered mechanisms within the mating strategies and reproductive biology of marine turtles that may allow for novel genetic input and facilitate enhanced gene flow among rookeries. Behavioral reproductive mechanisms, such as natal philopatry and polyandry, may mitigate potential impacts of depensation and contribute to the resilience of these species. © 2009 Society for Conservation Biology.
Abstract.
Bell CD, Blumenthal JM, Broderick AC, Godley BJ (2010). Investigating potential for depensation in marine turtles: how low can you go?.
Conserv Biol,
24(1), 226-235.
Abstract:
Investigating potential for depensation in marine turtles: how low can you go?
Where mechanisms inherent within the biology of a species affect individual fitness at low density, demographic-scale depensation may occur, hastening further decline and leading ultimately to population extirpation and species extinction. Reduction in fertility at low population densities has been identified in marine and terrestrial species. Using data on hatch success and hatchling-emergence success as proxies for fertilization success, we conducted a global meta-analysis of data from breeding aggregations of green turtles (Chelonia mydas) and loggerhead turtles (Caretta caretta). We found that there has been no reduction in fertility in small nesting aggregations in either of these species worldwide. We considered mechanisms within the mating strategies and reproductive biology of marine turtles that may allow for novel genetic input and facilitate enhanced gene flow among rookeries. Behavioral reproductive mechanisms, such as natal philopatry and polyandry, may mitigate potential impacts of depensation and contribute to the resilience of these species.
Abstract.
Author URL.
Blumenthal JM, Austin TJ, Bothwell JB, Broderick AC, Ebanks-Petrie G, Olynik JR, Orr MF, Solomon JL, Witt MJ, Godley BJ, et al (2010). Life in (and out of) the lagoon: Fine-scale movements of green turtles tracked using time-depth recorders.
Aquatic Biology,
9(2), 113-121.
Abstract:
Life in (and out of) the lagoon: Fine-scale movements of green turtles tracked using time-depth recorders
Tracking fine-scale movements in relation to threats is fundamental to the management of exploited marine species, yet there is considerable difficulty associated with gathering such data at sea. By combining a capture-recapture study with deployment of time-depth recorders (TDRs) and ultrasonic tags, we elucidated distribution and daily movements of juvenile green turtles Chelonia mydas exposed to a legal marine turtle fishery in the Cayman Islands. For instrumented turtles, distinct diel activity patterns were observed: dives during the day were shorter and more active than those at night, implying diurnal foraging and nocturnal resting. Spatially, while capture and recapture locations suggested fidelity to a shallow lagoon, when turtles were fitted with TDRs and ultra-sonic tags we demonstrated that they regularly moved out of the lagoon and onto the reef, where they could legally be captured in the marine turtle fishery. Our results are thus novel and valuable in a management context in that we demonstrated that seemingly protected aggregations of juvenile green turtles within a lagoon were, in fact, exposed to legal capture on a near-daily basis. This emphasizes the importance of assessing diel activity patterns of juvenile marine turtles, particularly with respect to directed take and other threats. © Inter-Research 2010.
Abstract.
Fuller WJ, Broderick AC, Enever R, Thorne P, Godley BJ (2010). Motile homes: a comparison of the spatial distribution of epibiont communities on Mediterranean sea turtles.
Journal of Natural History,
44(27), 1743-1753.
Abstract:
Motile homes: a comparison of the spatial distribution of epibiont communities on Mediterranean sea turtles
Understanding the ecological roles performed by an individual species requires knowledge from a wide range of disciplines; here we analyze the epibiont-host relationship found in marine turtles. During the study we recorded five new species of sea turtle epibiont: Laomedea flexuosa, Caprella fretensis, Hyale nilssoni, Hyale schmidti, Parasinelobus chevreuxi; as part of a total of nine zoological epibionts present on 35 female green turtles (Chelonia mydas) and 100 loggerhead turtles (Caretta caretta) nesting in Cyprus. The two most commonly occurring epibionts were acorn barnacles Chelonibia testudinaria and Chelonibia caretta, with larger specimens of both species recorded on loggerhead turtles. We analyzed the spatial distribution of these two barnacle species upon the carapaces of their hosts. Specimens of C. testudinaria situated on the anterior half of the carapace were larger than those located at the posterior. A significantly larger proportion of loggerhead turtles (152.5%) hosted epibionts in comparison to green turtles (30.3%). All non-barnacle epibionts were associated with either posterior algal mats or carapace scars. © 2010 Taylor & Francis.
Abstract.
Fuller WJ, Broderick AC, Enever R, Thorne P, Godley BJ (2010). Motile homes: a comparison of the spatial distribution of epibiont communities on Mediterranean sea turtles.
JOURNAL OF NATURAL HISTORY,
44(27-28), 1743-1753.
Author URL.
Witt MJ, Hawkes LA, Godfrey MH, Godley BJ, Broderick AC (2010). Predicting the impacts of climate change on a globally distributed species: the case of the loggerhead turtle.
J Exp Biol,
213(6), 901-911.
Abstract:
Predicting the impacts of climate change on a globally distributed species: the case of the loggerhead turtle.
Marine turtles utilise terrestrial and marine habitats and several aspects of their life history are tied to environmental features that are altering due to rapid climate change. We overview the likely impacts of climate change on the biology of these species, which are likely centred upon the thermal ecology of this taxonomic group. Then, focusing in detail on three decades of research on the loggerhead turtle (Caretta caretta L.), we describe how much progress has been made to date and how future experimental and ecological focus should be directed. Key questions include: what are the current hatchling sex ratios from which to measure future climate-induced changes? What are wild adult sex ratios and how many males are necessary to maintain a fertile and productive population? How will climate change affect turtles in terms of their distribution?
Abstract.
Author URL.
Hartnoll RG, Broderick AC, Godley BJ, Musick S, Pearson M, Stroud SA, Saunders KE (2010). Reproduction in the land crab Johngarthia lagostoma on Ascension Island.
Journal of Crustacean Biology,
30(1), 83-92.
Abstract:
Reproduction in the land crab Johngarthia lagostoma on Ascension Island
Reproduction was studied in the land crab Johngarthia lagostoma on Ascension Island in the central South Atlantic from 2005 to 2008. Both sexes are mature by 60-70 mm carapace width (the sample > 4,000 crabs consisted almost entirely of mature specimens). Breeding occurs around the east and south shores of the island, but was studied predominantly at the only easily accessible site at North East Bay. The annual breeding migration extends from January to May, with peak migration in March in most years. The intensity of migration varies between years, and is not obviously related to rainfall. There is lunar entrainment, with increased numbers at the shore in the first quarter, but largest numbers in the last quarter. Both males and females migrate, but with females in greater numbers. At the shore 80 of the crabs are females. A few females mate and lay eggs in the upland residential areas, a greater number do so on the migration route, but the majority only after reaching the shore. Reproductive investment per brood averaged 5% on a dry weight basis, and fecundity averaged 72,000 eggs. © 2010 the Crustacean Society.
Abstract.
Godley BJ, Barbosa C, Bruford M, Broderick AC, Catry P, Coyne MS, Formia A, Hays GC, Witt MJ (2010). Unravelling migratory connectivity in marine turtles using multiple methods.
Journal of Applied Ecology,
47(4), 769-778.
Abstract:
Unravelling migratory connectivity in marine turtles using multiple methods
Comprehensive knowledge of the fundamental spatial ecology of marine species is critical to allow the identification of key habitats and the likely sources of anthropogenic threats, thus informing effective conservation strategies. Research on migratory marine vertebrates has lagged behind many similar terrestrial animal groups, but studies using electronic tagging systems and molecular techniques offer great insights. Marine turtles have complex life history patterns, spanning wide spatio-temporal scales. As a result of this multidimensional complexity, and despite extensive effort, there are no populations for which a truly holistic understanding of the spatial aspects of the life history has been attained. There is a particular lack of information regarding the distribution and habitats utilized during the first few years of life. We used satellite tracking technology to track individual turtles following nesting at the green turtle Chelonia mydas nesting colony at Poilão Island, Guinea Bissau; the largest breeding aggregation in the eastern Atlantic. We further contextualize these data with pan-Atlantic molecular data and oceanographic current modelling to gain insights into likely dispersal patterns of hatchlings and small pelagic juveniles. All adult turtles remained in the waters of West Africa, with strong connectivity demonstrated with Banc D'Arguin, Mauritania. Despite shortcomings in current molecular markers, we demonstrate evidence for profound sub-structuring of marine turtle stocks across the Atlantic; with a high likelihood based on oceanographic modelling that most turtles from Guinea-Bissau are found in the eastern Atlantic. Synthesis and applications. There is an increased need for a better understanding of spatial distribution of marine vertebrates demonstrating life histories with spatio-temporal complexity. We propose the synergistic use of the technologies and modelling used here as a working framework for the future rapid elucidation of the range and likely key habitats used by the different life stages from such species. © 2010 the Authors. Journal compilation © 2010 British Ecological Society.
Abstract.
Witt MJ, Baert B, Broderick AC, Formia A, Fretey J, Gibudi A, Mounguengui GAM, Moussounda C, Ngouessono S, Parnell RJ, et al (2009). Aerial surveying of the world's largest leatherback turtle rookery: a more effective methodology for large-scale monitoring.
Biological Conservation,
142(8), 1719-1727.
Abstract:
Aerial surveying of the world's largest leatherback turtle rookery: a more effective methodology for large-scale monitoring
For many marine megavertebrate species it is challenging to derive population estimates and knowledge on habitat use needed to inform conservation planning. For marine turtles, the logistics required to undertake comprehensive ground-based censuses, across wide spatial and temporal scales, are often insurmountable. This frequently leads to an approach where a limited number of index nesting beaches are monitored in great detail by foot. In this study we use nationwide aerial surveying interfaced with ground assessments across three seasons of leatherback turtle nesting in Gabon (Equatorial West Africa), highlighting the importance of a synoptic approach to marine turtle monitoring. These surveys allow the first complete population assessment of this nesting aggregation to be made, identifying it as the world's largest for the species (36,185-126,480 clutches, approximating to 5865-20,499 breeding females per annum and a total estimate of 15,730 to 41,373 breeding females). Our approach also serendipitously provides insights into the spatial appropriateness of Gabon's protected areas network, for example (mean ± 1SD) 79 ± 6% (range 67-86%) of leatherback turtle activities recorded during aerial surveys (n = 8) occurred within protected areas (345 km, 58%, of surveyed coastline). We identify and discuss sources of potential error in estimating total nesting effort from aerial surveying techniques and show that interannual variation in nesting is considerable, which has implications for the detection of statistically significant changes in population size. Despite its relative costliness per day, aerial surveying can play an important role in providing estimates of relative population abundance of large vertebrates dispersed over extensive areas. Furthermore, it can provide data on habitat use and deliver real-time information on the spatial efficacy of protected area networks. © 2009 Elsevier Ltd. All rights reserved.
Abstract.
Hawkes LA, Broderick AC, Godfrey MH, Godley BJ (2009). Climate change and marine turtles.
Endangered Species Research,
7(2), 137-154.
Abstract:
Climate change and marine turtles
Marine turtles occupy a wide range of terrestrial and marine habitats, and many aspects of their life history have been demonstrated to be closely tied to climatic variables such as ambient temperature and storminess. As a group, therefore, marine turtles may be good indicators of climate change effects on coastal and marine habitats. Despite the small number of species in the taxon and a growing body of research in the field, the evidence base to predict resultant impacts of climate change remains relatively poor. We review the data from peer-reviewed publications to assess the likely impacts of climate change on marine turtles and highlight the types of data that would be most useful for an accurate assessment of future effects. The cumulative indications from these previous studies indicate that future research should focus on: (1) climate change effects on key habitats upon which turtles depend; (2) factors that influence nest site selection; (3) the consequences of skewed primary sex ratios; and (4) the effect of climate change on turtles at sea, for example range shifts and dietary breadth. Although it is too early to give detailed management recommendations, careful protection of coastlines along which turtles nest should be considered, as should the protection of beaches that produce male hatchlings, which may be of increased importance in the future. More active management approaches, for example translocation of eggs to suitable yet vacant nesting beaches, may be necessary to consider under worst-case scenarios. © Inter-Research 2009.
Abstract.
Campbell LM, Silver JJ, Gray NJ, Ranger S, Broderick AC, Fisher T, Godfrey MH, Gore S, Hodge KVD, Jeffers J, et al (2009). Co-management of sea turtle fisheries: Biogeography versus geopolitics. Marine Policy, 33, 137-145.
Blumenthal JM, Austin TJ, Bothwell JB, Broderick AC, Ebanks-Petrie G, Olynik JR, Orr MF, Solomon JL, Witt MJ, Godley BJ, et al (2009). Diving behavior and movements of juvenile hawksbill turtles Eretmochelys imbricata on a Caribbean coral reef.
Coral Reefs,
28(1), 55-65.
Abstract:
Diving behavior and movements of juvenile hawksbill turtles Eretmochelys imbricata on a Caribbean coral reef
As historically abundant spongivores, hawksbill turtles Eretmochelys imbricata likely played a key ecological role on coral reefs. However, coral reefs are now experiencing global declines and many hawksbill populations are critically reduced. For endangered species, tracking movement has been recognized as fundamental to management. Since movements in marine vertebrates encompass three dimensions, evaluation of diving behavior and range is required to characterize marine turtle habitat. In this study, habitat use of hawksbill turtles on a Caribbean coral reef was elucidated by quantifying diel depth utilization and movements in relation to the boundaries of marine protected areas. Time depth recorders (TDRs) and ultrasonic tags were deployed on 21 Cayman Islands hawksbills, ranging in size from 26.4 to 58.4 cm straight carapace length. Study animals displayed pronounced diel patterns of diurnal activity and nocturnal resting, where diurnal dives were significantly shorter, deeper, and more active. Mean diurnal dive depth (±SD) was 8 ± 5 m, range 2-20 m, mean nocturnal dive depth was 5 ± 5 m, range 1-14 m, and maximum diurnal dive depth was 43 ± 27 m, range 7-91 m. Larger individuals performed significantly longer dives. Body mass was significantly correlated with mean dive depth for nocturnal but not diurnal dives. However, maximum diurnal dive depth was significantly correlated with body mass, suggesting partitioning of vertical habitat by size. Thus, variable dive capacity may reduce intraspecific competition and provide resistance to degradation in shallow habitats. Larger hawksbills may also represent important predators on deep reefs, creating a broad ecological footprint over a range of depths. © 2008 Springer-Verlag.
Abstract.
Blumenthal JM, Austin TJ, Bell CDL, Bothwell JB, Broderick AC, Ebanks-Petrie G, Gibb JA, Luke KE, Olynik JR, Orr ME, et al (2009). Ecology of hawksbill turtles, Eretmochelys imbricata, on a western caribbean foraging ground.
Chelonian Conservation and Biology,
8(1), 1-10.
Abstract:
Ecology of hawksbill turtles, Eretmochelys imbricata, on a western caribbean foraging ground
We present results of an inwater research program focusing on basic ecology of juvenile hawksbill turtles (Eretmochelys imbricata) in the Cayman Islands. We made 206 captures of 135 hawksbills in Little Cayman and 103 captures of 97 hawksbills in Grand Cayman. The Cayman Islands aggregation demonstrated a broad size distribution (20.5-62.6 cm straight carapace length), slow growth rate (3.0 ± 0.9 cm/y), and multiple recaptures, suggesting long-term residence in some individuals. Demonstrated home range was small (mean distance from capture to recapture 545 ± 514 m, range 2-2080 m); although, an international tag return suggested a long-range developmental migration. Vertical features provided important habitat in Little Cayman, and larger turtles were generally captured in deeper waters. Behavior at sighting varied by habitat: resting, swimming, and feeding were observed in coral reef, reef wall, and hardbottom colonized by sponges and gorgonians, and resting was frequently observed in uncolonized hardbottom. Images obtained from underwater photographers show that hawksbills forage on sponges and occasionally on jellyfish. We observed an apparent commensal feeding relationship between hawksbills and 3 species of angelfish as well as aggressive interactions between hawksbills. We also documented causes of injury and mortality in the study area-including legal, illegal and incidental take, vessel collisions, hurricanes, and natural predation. © 2009 ChelonIan Research Foundation.
Abstract.
Pintus KJ, Godley BJ, McGowan A, Broderick AC (2009). Impact of clutch relocation on green turtle offspring.
Journal of Wildlife Management,
73(7), 1151-1157.
Abstract:
Impact of clutch relocation on green turtle offspring
For species with temperature-dependent sex determination, such as marine turtles, global climate change poses numerous threats. At the nesting beach, rising temperatures are predicted to further skew already female-biased sex ratios and increase embryonic mortality; sea-level rise and resultant coastal squeeze may leave few alternative breeding habitats in developed regions. As a result, clutch relocation, a commonly used management tool to reduce egg loss, may become necessary for safeguarding populations. Although studies have examined the impact of relocation on clutch success, few have examined the impact of this practice on the sex or phenotypic characteristics of hatchlings produced. We used a randomized block design experiment to examine effects of relocation on green turtle (Chelonia mydas) clutches. We compared hatching success, thermal conditions, and size (length and mass) of hatchlings from in situ control clutches with those subjected to 2 relocation methods, while controlling for maternal and other environmental effects. Relocated clutches did not vary significantly from control clutches in incubation temperature or inferred sex ratios during the critical middle third of incubation when sex is thought to be determined. Hatchling size was also unaffected by relocation. Both relocation methods, however, resulted in a 20 reduction in hatching success in comparison to in situ clutches. Clutch relocation is, however, likely to affect the population primary sex ratio, when clutches are relocated from sites in proximity to the sea where tidal inundation is a threat. Here, cooler conditions are likely to produce more males than are the warmer female-producing temperatures higher up the beach. For clutches at risk, relocation is a viable process and does not appear to affect hatchling size or predicted sex ratios if relocation sites are selected in areas utilized by other females. We urge caution, however, when moving clutches from potentially male-producing sites, particularly given predicted impacts of climate change on already female-biased sex ratios. © 2009 the Wildlife Society.
Abstract.
Fuller WJ, Broderick AC, Hooker SK, Witt MJ, Godley BJ (2009). Insights into habitat utilization by Green Turtles (Chelonia Mydas) during the inter-nesting period animal-borne digital cameras.
Marine Technology Society Journal,
43(3), 51-59.
Abstract:
Insights into habitat utilization by Green Turtles (Chelonia Mydas) during the inter-nesting period animal-borne digital cameras
Many marine turtle habitat utilization studies have historically relied on inferences from logged data or direct visual observation. Here we remotely investigate aspects of the habitat utilization of inter-nesting female green turtles (Chelonia mydas) nesting on the Mediterranean island of Cyprus. Using an animal- borne digital video camera set to take only still images, with an integrated time-depth recorder, we recorded a total of 2, 375 images and 2, 899 dives for two nesting female green turtles. Both turtles spent over 80% of their time at depths of 5 m or less. Photographic evidence allowed us to categorize subsurface behaviors from 66 of the deeper dives (turtle a with 40 dives and turtle B with 26 dives) containing more than 900 images into three categories: swimming, probable foraging and resting. Methodologically, our study highlights future utility in using camera technologies to clarify at-sea behavior of marineorganisms, with a view to generating reliable time budgets.
Abstract.
Inger R, Attrill MJ, Bearhop S, Broderick AC, Grecian WJ, Hodgson DJ, Sheehan E, Votier SC, Witt MJ, Godley BJ, et al (2009). Marine Renewable Energy: potential benefits to biodiversity? an urgent call for research.
Journal of Applied Ecology,
46, 1145-1153.
Abstract:
Marine Renewable Energy: potential benefits to biodiversity? an urgent call for research.
1. The evidence for anthropogenically induced climate change is overwhelming with the production of greenhouse gases from burning fossil fuels being a key driver. In response, many governments have initiated programmes of energy production from renewable sources.
2. The marine environment presents a relatively untapped energy source and offshore installations are likely to produce a significant proportion of future energy production. Wind power is the most advanced, with development of wave and tidal energy conversion devices expected to increase worldwide in the near future.
3. Concerns over the potential impacts on biodiversity of marine renewable energy installations (MREI) include: habitat loss, collision risks, noise and electromagnetic fields. These factors have been posited as having potentially important negative environmental impacts.
4. Conversely, we suggest that if appropriately managed and designed, MREI may increase local biodiversity and potentially benefit the wider marine environment. Installations have the capacity to act as both artificial reefs and fish aggregation devices, which have been used previously to facilitate restoration of damaged ecosystems, and de facto marine-protected areas, which have proven successful in enhancing both biodiversity and fisheries.
5. The deployment of MREI has the potential to cause conflict among interest groups including energy companies, the fishing sector and environmental groups. Conflicts should be minimized by integrating key stakeholders into the design, siting, construction and operational phases of the installations, and by providing clear evidence of their potential environmental benefits.
6. Synthesis and applications. MREI have the potential to be both detrimental and beneficial to the environment but the evidence base remains limited. To allow for full biodiversity impacts to be assessed, there exists an urgent need for additional multi and inter-disciplinary research in this area ranging from engineering to policy. Whilst there are a number of factors to be considered, one of the key decisions facing current policy makers is where installations should be sited, and, dependent upon site, whether they should be designed to either minimize negative environmental impacts or as facilitators of ecosystem restoration.
Abstract.
Author URL.
Inger R, Attrill MJ, Bearhop S, Broderick AC, James Grecian W, Hodgson DJ, Mills C, Sheehan E, Votier SC, Witt MJ, et al (2009). Marine renewable energy: Potential benefits to biodiversity? an urgent call for research.
Journal of Applied Ecology,
46(6), 1145-1153.
Abstract:
Marine renewable energy: Potential benefits to biodiversity? an urgent call for research
The evidence for anthropogenically induced climate change is overwhelming with the production of greenhouse gases from burning fossil fuels being a key driver. In response, many governments have initiated programmes of energy production from renewable sources. 2. The marine environment presents a relatively untapped energy source and offshore installations are likely to produce a significant proportion of future energy production. Wind power is the most advanced, with development of wave and tidal energy conversion devices expected to increase worldwide in the near future. 3. Concerns over the potential impacts on biodiversity of marine renewable energy installations (MREI) include: habitat loss, collision risks, noise and electromagnetic fields. These factors have been posited as having potentially important negative environmental impacts. 4. Conversely, we suggest that if appropriately managed and designed, MREI may increase local biodiversity and potentially benefit the wider marine environment. Installations have the capacity to act as both artificial reefs and fish aggregation devices, which have been used previously to facilitate restoration of damaged ecosystems, and de facto marine-protected areas, which have proven successful in enhancing both biodiversity and fisheries. 5. The deployment of MREI has the potential to cause conflict among interest groups including energy companies, the fishing sector and environmental groups. Conflicts should be minimized by integrating key stakeholders into the design, siting, construction and operational phases of the installations, and by providing clear evidence of their potential environmental benefits. 6. Synthesis and applications. MREI have the potential to be both detrimental and beneficial to the environment but the evidence base remains limited. To allow for full biodiversity impacts to be assessed, there exists an urgent need for additional multi and inter-disciplinary research in this area ranging from engineering to policy. Whilst there are a number of factors to be considered, one of the key decisions facing current policy makers is where installations should be sited, and, dependent upon site, whether they should be designed to either minimize negative environmental impacts or as facilitators of ecosystem restoration. © 2009 British Ecological Society.
Abstract.
Richardson PB, Bruford MW, Calosso MC, Campbell LM, Clerveaux W, Formia A, Godley BJ, Henderson AC, McClellan K, Newman S, et al (2009). Marine turtles in the Turks and Caicos Islands: Remnant rookeries, regionally significant foraging stocks, and a major turtle fishery.
Chelonian Conservation and Biology,
8(2), 192-204.
Abstract:
Marine turtles in the Turks and Caicos Islands: Remnant rookeries, regionally significant foraging stocks, and a major turtle fishery
This study reviews the status of marine turtles in the Turks and Caicos Islands (TCI) using data gathered during a multidisciplinary study involving field surveys, questionnaire-based interviews, and molecular genetics between 2002 and 2006. Large aggregations of foraging turtles in the archipelago's waters are dominated by juvenile green (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata), with provisional mixed-stock analysis of these species suggesting that the aggregations originate predominantly from larger and relatively proximate source rookeries in the Wider Caribbean region. This study also suggests that the islands host remnant nesting populations of turtles, with hawksbill turtle nests recorded more frequently than green and loggerhead turtle (Caretta caretta) nests. The TCI islanders retain a culture of turtle use, with the current regulated and legitimate harvest likely to be one of the largest among the Caribbean Islands. This study suggests that historic and current harvest of turtles and their eggs in the TCI may have contributed to the apparent decline in the country's nesting populations. In order to address this conservation concern, changes to the regulation and management of the TCI's turtle fishery are necessary, but further research is needed to inform these changes. © 2009 Chelonian Research Foundation.
Abstract.
Hartnoll RG, Broderick AC, Godley BJ, Saunders KE (2009). POPULATION STRUCTURE OF THE LAND CRAB <i>JOHNGARTHIA LAGOSTOMA</i> ON ASCENSION ISLAND (VOL 29, PG 57, 2009).
JOURNAL OF CRUSTACEAN BIOLOGY,
29(2), 281-281.
Author URL.
Hartnoll RG, Broderick AC, Godley BJ, Saunders KE (2009). Population structure of the land crab Johngarthia lagostoma on ascension Island.
Journal of Crustacean Biology,
29(1), 57-61.
Abstract:
Population structure of the land crab Johngarthia lagostoma on ascension Island
The population structure of the land crab Johngarthia lagostoma was studied on Ascension Island from 2005-2007, predominantly during the period of the seaward breeding migrations; approximately 4000 crabs were examined. Sex ratio varied according to location of sampling. Males predominated in permanent residential areas on high ground. Sexes were equal along migration routes to the sea. Females predominated in the breeding sites on the shore. Very few immature crabs (< 60 mm CW) were found. Males had modal and maximum sizes of 100-109 mm and 120 mm CW, females of 90-99 mm and 110 mm, respectively. An aging population is indicated. Crabs < 40 mm CW were all dark coloured, and colour variation into yellow, purple and intermediate morphs developed between 40-50 mm CW.Overall colour distribution of the population was 85% yellow, 5% intermediate, and 10% purple. Yellow morphs were more abundant in females (89%) than males (81%). The predominance of yellow morphs may be an adaptation to reduce heat stress.
Abstract.
Blumenthal JM, Abreu-Grobois FA, Austin TJ, Broderick AC, Bruford MW, Coyne MS, Ebanks-Petrie G, Formia A, Meylan PA, Meylan AB, et al (2009). Turtle groups or turtle soup: dispersal patterns of hawksbill turtles in the Caribbean.
Mol Ecol,
18(23), 4841-4853.
Abstract:
Turtle groups or turtle soup: dispersal patterns of hawksbill turtles in the Caribbean.
Despite intense interest in conservation of marine turtles, spatial ecology during the oceanic juvenile phase remains relatively unknown. Here, we used mixed stock analysis and examination of oceanic drift to elucidate movements of hawksbill turtles (Eretmochelys imbricata) and address management implications within the Caribbean. Among samples collected from 92 neritic juvenile hawksbills in the Cayman Islands we detected 11 mtDNA control region haplotypes. To estimate contributions to the aggregation, we performed 'many-to-many' mixed stock analysis, incorporating published hawksbill genetic and population data. The Cayman Islands aggregation represents a diverse mixed stock: potentially contributing source rookeries spanned the Caribbean basin, delineating a scale of recruitment of 200-2500 km. As hawksbills undergo an extended phase of oceanic dispersal, ocean currents may drive patterns of genetic diversity observed on foraging aggregations. Therefore, using high-resolution Aviso ocean current data, we modelled movement of particles representing passively drifting oceanic juvenile hawksbills. Putative distribution patterns varied markedly by origin: particles from many rookeries were broadly distributed across the region, while others would appear to become entrained in local gyres. Overall, we detected a significant correlation between genetic profiles of foraging aggregations and patterns of particle distribution produced by a hatchling drift model (Mantel test, r = 0.77, P < 0.001; linear regression, r = 0.83, P < 0.001). Our results indicate that although there is a high degree of mixing across the Caribbean (a 'turtle soup'), current patterns play a substantial role in determining genetic structure of foraging aggregations (forming turtle groups). Thus, for marine turtles and other widely distributed marine species, integration of genetic and oceanographic data may enhance understanding of population connectivity and management requirements.
Abstract.
Author URL.
Aiken JJ, Godley BJ, Broderick AC, Austin T, Ebanks-Petrie G, Hays GC (2009). Two hundred years after a commercial marine turtle fishery: the current status of marine turtles nesting in the Cayman Islands. Oryx, 35(02), 145-145.
Broderick, A.C. Frett, G. Gore, S. (2008). Down But Not Out: Marine Turtles of the British Virgin Islands. Animal Conservation
Jackson AL, Broderick AC, Fuller WJ, Glen F, Ruxton GD, Godley BJ (2008). Sampling design and its effect on population monitoring: How much monitoring do turtles really need?.
Biological ConservationAbstract:
Sampling design and its effect on population monitoring: How much monitoring do turtles really need?
Marine turtles are a taxon of world-wide conservation concern. Effective long-term monitoring is hampered by the fact that populations are widely dispersed except during the breeding season. Thus most monitoring programmes focus on nesting beaches, necessitating resource intensive studies, often over months, that could conceivably, be less comprehensive and focus on more parsimonious sampling. We analyse 11 years of exhaustive monitoring data for two species of Mediterranean marine turtles (Chelonia mydas and Caretta caretta). We resample using a variety of plausible sub-sampling regimens to estimate the total annual nesting population. We project our dataset into the future applying a range of population change rates to explore how adopting a monitoring programme based on sub-sampling would, for example, affect our ability to detect population decline. We show that accurate annual population estimates can be achieved with as few as 14 days of survey effort providing monitoring spans the peak of nesting. Furthermore, the modelled impact of sampling-based monitoring suggests that the duration to detect population change is not increased greatly. Our findings have implications for all marine turtle monitoring and have applicability to other animal groups. It is often considered desirable to perform exhaustive monitoring, with aversion of basing policy recommendations on partial data. However, comprehensive long-term monitoring programmes, particularly in developing nations, although presenting a number of advantages, are often impossible. Accurate total annual censuses can be achieved through a variety of sub-sampling regimens without sacrificing the ability to detect changes in the population trends over time. In this example, a solid block of at least 3 weeks sampling that encompasses the peak of the nesting season is advised. © 2008 Elsevier Ltd. All rights reserved.
Abstract.
Jackson AL, Broderick AC, Fuller WJ, Glen F, Ruxton GD, Godley BJ (2008). Sampling design and its effect on population monitoring: How much monitoring do turtles really need?.
BIOLOGICAL CONSERVATION,
141(12), 2932-2941.
Author URL.
Broderick, A.C. Coyne, M.S. Formia, A. (2008). Satellite tracking highlights difficulties in the design of effective protected areas for leatherback turtles during the internesting period. Oryx
Godley BJ, Blumenthal JM, Broderick AC, Coyne MS, Godfrey MH, Hawkes LA, Witt MJ (2008). Satellite tracking of sea turtles: Where have we been and where do we go next?.
Endangered Species Research,
4, 3-22.
Author URL.
Mcgowan A, Broderick AC, Godley BJ (2008). Seabird populations of the Chagos Archipelago, Indian Ocean: an evaluation of IBA sites.
ORYX,
42(3), 424-429.
Author URL.
Leeney RH, Amies R, Broderick AC, Witt MJ, Loveridge J, Doyle J, Godley BJ (2008). Spatio-temporal analysis of cetacean strandings and bycatch in a UK fisheries hotspot. Biodiversity and Conservation
Fuller WJ, Broderick AC, Phillips RA, Silk JRD, Godley BJ (2008). Utility of geolocating light loggers for indicating at-sea movements in sea turtles. Endangered Species Research, 4, 139-146.
McGowan A, Woodfield NK, Hilton G, Broderick AC, Godley BJ (2007). A rigorous assessment of the Avifauna of a small Caribbean Island: a case study in Anegada, British Virgin Islands.
Caribbean Journal of Science,
43(1), 99-116.
Abstract:
A rigorous assessment of the Avifauna of a small Caribbean Island: a case study in Anegada, British Virgin Islands
The avifauna of the British Virgin Islands (BVI) has received little attention from researchers. The lack of baseline information is therefore a major hindrance to the construction of management plans. Here we present detailed monitoring data on the species composition and numbers of each-species for the island of Anegada, BVI. We surveyed the birds of Anegada between November 2003 and March 2005 utilising a combination of coastal transects, wetland bird counts, point counts, and species-specific survey methods for nocturnal species. A total of 99 different species were recorded, with a large increase in the number of species and number of individuals centred around peak migration in September. Although there is a depauperate terrestrial bird community consisting of predominately generalist species, it holds important populations of regional avifauna. For example, it hosts five regionally important breeding seabird colonies and its wetlands provide an important stop-over and over-wintering site for many species of shorebirds and waterbirds. In addition, the Eastern salt ponds are also the only breeding site for the greater flamingo, Phoenicopterus ruber, within the territory. We discuss our findings within the current framework of regional conservation and provide recommendations for the implementation of a territory wide monitoring program as a first step towards meeting the UK's commitments under several multilateral environmental agreements. Copyright 2007 College of Arts and Science.
Abstract.
Woodfield, N.K. Hilton, G. Broderick, A.C. (2007). An assessment of the avifauna of a small remote island: a case study of Anegada, British Virgin Islands. Caribbean Journal of Science
Broderick AC, Coyne MS, Fuller WJ, Glen F, Godley BJ (2007). Correction for Broderick. <i>et al.</i>. Fidelity and over-wintering of sea turtles.
Proceedings of the Royal Society B: Biological Sciences,
274(1629), 3183-3183.
Abstract:
Correction for Broderick. et al.. Fidelity and over-wintering of sea turtles
. Correction for ‘Fidelity and over-wintering of sea turtles’ by Annette C. Broderick, Michael S. Coyne, Wayne J. Fuller, Fiona Glen and Brendan J. Godley (Proc. R. Soc. B
. 274
. 1533–1538.
(doi:
. 10.1098/rspb.2007.0211
. )).
.
. The scale bar in figure 2b was incorrect, and should read as follows: 5 km.
Abstract.
Broderick AC, Coyne MS, Fuller WJ, Glen F (2007). Fidelity and over-wintering of sea turtles. Proceedings of the Royal Society B Biological Sciences, 274(1617), 1533-1538.
Formia A, Broderick AC, Glen F, Godley BJ, Hays GC, Bruford MW (2007). Genetic composition of the Ascension Island green turtle rookery based on mitochondrial DNA: implications for sampling and diversity.
Endangered Species Research,
3, 145-158.
Author URL.
HAWKES LA, BRODERICK AC, GODFREY MH, GODLEY BJ (2007). Investigating the potential impacts of climate change on a marine turtle population. Global Change Biology, 0(0), 070621084512044-???.
Hawkes LA, Broderick AC, Godfrey MH, Godley BJ (2007). Investigating the potential impacts of climate change on marine turtles. Global Change Biology, 13(5), 923-932.
Solomon, J.L. Blumenthal, J.M. Austin, T.J. (2007). Monitoring and conservation of critically reduced marine turtle nesting populations: lessons from the Cayman Islands. Animal Conservation, 10, 39-47.
Hawkes LA, Broderick AC, Godfrey MS, Coyne MS, Godley BJ (2007). Only some like it hot: quantifying the environmental niche of loggerhead sea turtles. Diversity and Distributions, 13(4), 447-457.
Witt MJ, Broderick AC, Johns DJ, Martin C, Penrose R, Hoogmoed MS, Godley BJ (2007). Prey landscapes help identify potential foraging habitats for leatherback turtles in the NE Atlantic.
Marine Ecology Progress Series,
337, 231-243.
Abstract:
Prey landscapes help identify potential foraging habitats for leatherback turtles in the NE Atlantic
Identifying key marine megavertebrate habitats has become ever more important as concern increases regarding global fisheries bycatch and accelerated climate change. This will be aided by a greater understanding of the patterns and processes determining the spatiotemporal distribution of species of conservation concern. We identify probable foraging grounds for leatherback turtles in the NE Atlantic using monthly landscapes of gelatinous organism distribution constructed from Continuous Plankton Recorder Survey data. Using sightings data (n = 2013 records, 1954 to 2003) from 9 countries (UK, Ireland, France, Belgium, the Netherlands, Denmark, Germany, Norway and Sweden), we show sea surface temperatures of approximately 10 to 12°C most likely indicate the lower thermal threshold for accessible habitats during seasonal foraging migrations to high latitudes. Integrating maps of gelatinous plankton as a possible indicator of prey distribution with thermal tolerance parameters demonstrates the dynamic (spatial and temporal) nature of NE Atlantic foraging habitats. We highlight the importance of body size-related thermal constraints in structuring leatherback foraging populations and demonstrate a latitudinal gradient in body size (Bergmann's rule) where smaller animals are excluded from higher latitude foraging areas. We highlight the marine area of the European continental shelf edge as being both thermally accessible and prey rich, and therefore potentially supporting appreciable densities of foraging leatherbacks, with some suitable areas not yet extensively surveyed. © Inter-Research 2007.
Abstract.
Broderick, A.C. Johns, D.J. Martin, C.S. (2007). Prey landscapes help identify potential foraging habitats for leatherback turtles in the northeast Atlantic. Marine Ecology Progress Series, 337, 231-244.
Blumenthal, J.M. Broderick, A.C. Coyne, M.S. (2007). Satellite tracking of sea turtles: Where have we been and where do we go next?. Endangered Species Research, 3(16).
Witt MJ, Penrose R, Godley BJ (2007). Spatio-temporal patterns of juvenile marine turtle occurrence in waters of the European continental shelf.
Marine Biology,
151(3), 873-885.
Abstract:
Spatio-temporal patterns of juvenile marine turtle occurrence in waters of the European continental shelf
We present data spanning approximately 100 years regarding the spatial and temporal occurrence of marine turtle sightings and strandings in the northeast Atlantic from two public recording schemes and demonstrate potential signals of changing population status. Records of loggerhead (n = 317) and Kemp's ridley (n = 44) turtles occurring on the European continental shelf were most prevalent during the autumn and winter, when waters were coolest. In contrast, endothermic leatherback turtles (n = 1,668) were most common during the summer. Analysis of the spatial distribution of hard-shell marine turtle sightings and strandings highlights a pattern of decreasing records with increasing latitude. The spatial distribution of sighting and stranding records indicates that arrival in waters of the European continental shelf is most likely driven by North Atlantic current systems. Future patterns of spatial-temporal distribution, gathered from the periphery of juvenile marine turtles habitat range, may allow for a broader assessment of the future impacts of global climate change on species range and population size. © 2006 Springer-Verlag.
Abstract.
Broderick AC, Frauenstein R, George T, Glen F (2006). Are green turtles globally endangered?. Global Ecology and Biogeography, 15(1), 21-26.
McGowan A, Gore S, Broderick A, Hilton G, Woodfield N, Godley B (2006). Breeding seabirds in the British Virgin Islands. Endangered Species Research, 2, 15-20.
Broderick, A.C. Gore, S. Hilton, G. (2006). Breeding seabirds in the British Virgin Islands.
Endangered Species Research,
3, 1-6.
Author URL.
Broderick, A.C. Campbell, L.M. Godley, B.J. (2006). Marine turtle fisheries in the UK Overseas Territories of the Caribbean: domestic legislation and the requirements of multilateral agreements. Journal of International Wildlife Law and Policy, 9, 223-246.
Godley, B.J. Dontaine, M.W. Bruford (2006). Mitochondrial DNA diversity and phylogeography of endangered green turtle (Chelonia mydas) populations in Africa. Conservation Genetics, 7, 353-369.
Hawkes LA, Broderick AC, Coyne MS, Godfrey MH, Lopez-Jurado LF, Lopez-Suarez P, Merino SE, Varo-Cruz N, Godley BJ (2006). Phenotypically linked dichotomy in sea turtle foraging strategies requires multiple conservation approaches. Current Biology, 16(10), 990-995.
Broderick, A.C. Godley, B.J. Hays, G.C. (2006). Rhythmic Throat Oscillations in Nesting Green Turtles (Chelonia mydas). Chelonian Conservation and Biology, 5, 299-301.
Solomon, J.L. Bell, C.D. Austin, T.J. (2006). Satellite tracking highlights the need for international cooperation in marine turtle management.
Endangered Species Research,
2, 51-61.
Author URL.
Broderick, A.C. Godley, B.J. Hays, G.C. (2006). Thermal control of hatchling emergence patterns in marine turtles. Journal of Experimental Marine Biology and Ecology, 334, 31-42.
Blumenthal, J.M. Austin, T.J. Solomon, J.L. (2006). Traditional Caymanian fishery may impede local marine turtle population recovery.
Endangered Species Research,
2, 63-69.
Author URL.
Broderick, A.C. Godley, B.J. Hays, G.C. (2005). Patterns in the emergence of. green (Chelonia mydas) and loggerhead (Caretta caretta) turtle hatchlings from their nests. Marine Biology, 146, 1039-1049.
Parsons, J. Austin, T.J. Broderick, A.C. (2005). Some of them came home: the Cayman Turtle Farm headstarting project for the green turtle Chelonia mydas. Oryx, 39, 137-148.
Hawkes LA, Broderick, A.C. Godfrey, M.H. Godley, B.J. (2005). Status of nesting loggerhead turtles Caretta caretta at Bald Head Island (North Carolina, USA) after 24 years of intensive monitoring and conservation. Oryx, 39, 65-72.
Hays GC, Broderick AC, Godley BJ, Luschi P, Nichols WJ, Chaloupka M, Parker D, Balazs G (2004). Tracking turtles to their death. Marine Ecology Progress Series, 283, 299-302.
Broderick, A.C. Glen, F. Godley, B.J. (2003). Climate change and sea turtles: a 150-year reconstruction of incubation temperatures at a major marine turtle rookery. Global Change Biology, 9, 642-646.
Broderick, A.C. Godley, B.J. Hays, G.C. (2003). Incubation environment affects phenotype of naturally incubated green turtle hatchlings. Journal of the Marine Biological Association of the United Kingdom, 83, 1183-1186.
Åkesson, S. Broderick, A.C. Glen, F. (2003). Island finding ability of marine turtles. Proceedings of the Royal Society B, 270, S5-S7.
Lima, E. HS, M. Åkesson, S. (2003). Movement patterns of green turtles in Brazilian coastal waters described by satellite tracking and flipper tagging. Marine Ecology Progress Series, 253:279-288
Broderick, A.C. Glen, F. Godley, B.J. (2003). Multiple paternity assessed using microsatellite markers, in green turtles Chelonia mydas (Linnaeus, 1758) of Ascension Island, South Atlantic. Journal of Experimental Marine Biology and Ecology, 291, 149-160.
Broderick, A.C. Glen, F. Godley, B.J. (2003). Navigation by green turtles: which strategy do displaced adults use to find Ascension Island?. Oikos, 103, 363-372.
Broderick, A.C. Glen, F. Hays, G.C. (2003). Post-nesting movements and submergence patterns of loggerhead marine turtles in the Mediterranean assessed by satellite tracking. Journal of Experimental Marine Biology and Ecology, 287, 119-134.
Broderick, A.C. Godley, B.J. Luschi, P. (2003). Satellite telemetry suggests high levels of fishing-induced mortality in marine turtles. Marine Ecology Progress Series, 262, 305-309.
Glen, F. Godley, B.J. Hays, G.C. (2003). Variation in reproductive output of marine turtles. Journal of Experimental Marine Biology and Ecology, 288, 95-109.
Glen, F. Broderick, A.C. Godley, B.J. (2002). Behavioural plasticity in a large marine herbivore: contrasting patterns of depth utilisation between two green turtle (Chelonia mydas) populations. Marine Biology, 141, 985-990.
Broderick, A.C. Godley, B.J. Lovell, P. (2002). Bi-phasal long-distance migration in green turtles. Animal Behaviour, 64, 895-898.
Broderick, A.C. Godley, B.J. Hays, G.C. (2002). Diving behaviour during the internesting interval for loggerhead turtles (Caretta caretta) nesting in Cyprus. Marine Ecology Progress Series, 227, 63-70.
Glen, F. Godley, B.J. Hays, G.C. (2002). Estimating the number of Green and Loggerhead Turtles nesting annually in the Mediterranean. Oryx, 36: 227-236
Barbosa, C. Indjai, B. Almeida, A. (2002). First census of the green turtle at Poilao, Bijagos Archipelago, Guinea-Bissau: the most important nesting colony on the Atlantic coast of Africa. Oryx, 36, 400-403.
Godley BJ, Broderick AC, Coyne MS, Richardson S (2002). Long-term satellite telemetry of the movements and habitat utilisation by green turtles in the Mediterranean. Ecography, 25(3), 352-362.
Broderick, A.C. Frauenstein, R. (2002). Reproductive seasonality and sexual dimorphism in green turtles. Marine Ecology Progress Series, 226, 125-133.
Broderick, A.C. Glen, F. (2002). Temperature dependent sex determination of Ascension Island green turtles. Marine Ecology Progress Series, 226, 115-124.
Broderick, A.C. Godley, B.J. West, S.A. (2002). The effects of incubation environment, sex and pedigree on the hatchling phenotype in a natural population of loggerhead turtles. Evolutionary Ecology Research, 4, 737-748.
Broderick, A.C. Glen, F. Godley, B.J. (2002). Water temperature and internesting intervals for loggerhead (Caretta caretta) and green (Chelonia mydas) sea turtles. Journal of Thermal Biology, 27, 429-432.
Broderick, A.C. Glen, F. Godley, B.J. (2002). Weight change associated with long-term fasting in a marine reptile: the case of green turtles (Chelonia mydas) at Ascension Island. Canadian Journal of Zoology, 80, 1299-1302.
Broderick, A.C. Deeming, J. Godley, B.J. (2001). Dipteran infestation of loggerhead (Caretta caretta), and green (Chelonia mydas), sea turtle nests in northern Cyprus. Journal of natural History, 35, 573-581.
Broderick, A.C. Godley, B.J. Metcalfe, J.D. (2001). Dive angles for a green turtle (Chelonia mydas). Journal of Marine Biological Association(UK), 81, 683-686.
Godley B, Broderick, A.C. Mrosovsky, N. (2001). Estimating hatchling sex ratios of loggerhead turtles in Cyprus from incubation durations. Marine Ecology Progress Series, 210, 195-201.
Broderick AC, Godley BJ, Hays GC (2001). Metabolic heating and the prediction of sex ratios for green turtles (Chelonia mydas). Physiological and Biochemical Zoology, 74(2), 161-170.
McGowan A, Rowe, L.V. Broderick, A.C. Godley, B.J. (2001). Nest factors predisposing loggerhead sea turtle (Caretta caretta) clutches to infestation by dipteran larvae on northern Cyprus. Copeia, 2001(3), 808-812.
Godley B, Broderick, A.C. Hays, G.C. (2001). Nesting of green turtles Chelonia mydas at Ascension Island, South Atlantic. Biological Conservation, 97, 151-158.
Godley, B.J. Broderick, A.C. (2001). Nesting of the Green Turtle, Chelonia mydas, in the Mediterranean: a review of status and conservation needs. Zoology in the Middle East, 24, 45-74.
Åkesson S, Luschi P, Broderick AC, Glen F, Godley BJ, Papi F, Hays GC (2001). Oceanic long-distance navigation: Do experienced migrants use the earth's magnetic field?.
Journal of Navigation,
54(3), 419-427.
Abstract:
Oceanic long-distance navigation: Do experienced migrants use the earth's magnetic field?
Albatrosses and sea turtles are known to perform extremely long-distance journeys between disparate feeding areas and breeding sites located on small, isolated, oceanic islands or at specific coastal sites. These oceanic journeys, performed mainly over or through apparently featureless mediums, indicate impressive navigational abilities, and the sensory mechanisms used are still largely unknown. This research used three different approaches to investigate whether bi-coordinate navigation based on magnetic field gradients is likely to explain the navigational performance of wandering albatrosses in the South Atlantic and Indian Oceans and of green turtles breeding on Ascension Island in the South Atlantic Ocean. The possibility that magnetic field parameters can potentially be used in a bi-coordinate magnetic map by wandering albatrosses in their foraging area was investigated by analysing satellite telemetry data published in the literature. The possibilities for using bi-coordinate magnetic navigation varied widely between different areas of the Southern Oceans, indicating that a common mechanism, based on a bi-coordinate geomagnetic map alone, was unlikely for navigation in these areas. In the second approach, satellite telemetry was used to investigate whether Ascension Island green turtles use magnetic information for navigation during migration from their breeding island to foraging areas in Brazilian coastal waters. Disturbing magnets were applied to the heads and carapaces of the turtles, but these appeared to have little effect on their ability to navigate. The only possible effect observed was that some of the turtles with magnets attached were heading for foraging areas slightly south of the control turtles along the Brazilian coast. In the third approach, breeding female green turtles were deliberately displaced in the waters around Ascension Island to investigate which cues these turtles might use to locate and return to the island; the results suggested that cues transported by wind might be involved in the final stages of navigation.
Abstract.
Åkesson S, Luschi P, Papi F, Broderick AC, Glen F, Godley BJ, Hays GC (2001). Oceanic long-distance navigation:: Do experienced migrants use the Earth's magnetic field?.
JOURNAL OF NAVIGATION,
54(3), 419-427.
Author URL.
Luschi P, Åkesson, S. Broderick, A.C. Glen, F. Godley BJ, Papi F, Hays GC (2001). Testing animal navigational abilities in the ocean: displacement experiments on sea turtles. Behavioral Ecology and Sociobiology, 50, 528-534.
Åkesson, S. Broderick, A.C. Glen, F. (2001). The diving behaviour of green turtles undertaking oceanic migration to and from Ascension Island: dive durations, dive profiles and depth distribution. Journal of Experimental Biology, 204, 4093-4098.
Åkesson, S. Godley, B.J. Luschi, P. (2001). The implications of location accuracy for the interpretation of satellite tracking data. Animal Behaviour, 61, 1035-1040.
Hays GC, Ashworth, J.S. Barnsley, M.J. Broderick, A.C. Emery DR, Godley BJ, Henwood A, Jones EL (2001). The importance of sand albedo for the thermal conditions on sea turtle nesting beaches. Oikos, 93, 87-95.
Godley, B.J. Broderick, A.C. Glen, F. (2001). The movements and submergence behaviour of male green turtles at Ascension Island. Marine Biology, 139, 395-399.
Godley BJ, Broderick, A.C. Downie, J.R. Glen, F. Houghton JDR, Kirkwood I, Reece S, Hays GC (2001). Thermal conditions in nests of loggerhead turtles: further evidence suggesting female skewed sex ratios of hatchling production in the Mediterranean. Journal of Experimental Marine Biology and Ecology, 97, 45-63.
Broderick AC, Godley BJ, Hays GC (2001). Trophic status drives inter-annual variability in nesting numbers of marine turtles. Proceedings of the Royal Society B Biological Sciences, 268(1475), 1481-1487.
Godley, B.J. Broderick, A.C. Austin, T. (2001). Two hundred years after a commercial marine turtle fishery: the current status of marine turtles nesting in the Cayman Islands. Oryx, 35, 145-152.
Hochscheid, S. Broderick, A.C. Godley, B.J. (2000). Diving behaviour of green turtles: dive depth, dive duration and activity levels. Marine Ecology Progress Series, 208, 297-298.
Godley, B.J. Reece, S. Downie, J.R. (2000). Incubation periods and sex ratios of green turtles: highly female biased hatchling production in the eastern Mediterranean. Marine Ecology Progress Series, 202, 273-281.
Adams, C.R. Broderick, A.C. Godley, B.J. (2000). The diving behaviour of green turtles at Ascension island. Animal Behaviour, 59, 577-586.
Godley, B.J. (1999). Effect of tagging marine turtles on nesting behaviour and reproductive success. Animal Behaviour, 58, 587-591.
Godley, B.J. Broderick, A.C. (1999). Long-term thermal conditions on the nesting beaches of green turtles on Ascension Island. Marine Ecology Progress Series, 185, 297-299.
Godley, B.J. Broderick, A.C. Wilson, R.P. (1999). Reptilian diving: highly variable dive patterns in the green turtle (Chelonia mydas). Marine Ecology Progress Series, 185, 101-112.
Broderick, A.C. Moraghan, S. (1999). Short term effectiveness of Passive Integrated Transponders (PITs) used in the study of Mediterranean marine turtles. Chelonian Conservation and Biology, 3, 477-479.
Gucu, A.C. Broderick, A.C. Furness, R.W. (1998). Interaction between marine turtles and artisanal fisheries in the eastern Mediterranean: a probable cause for concern?. Zoology in the Middle East, 16, 49-64.
Broderick, A.C. Catry, P. (1998). Marine Turtles in the Orango National Park (Bijagós Archipelago, Guinea-Bissau). Marine Turtle Newsletter, 81, 6-7.
Casale, P. Bradai, M.N. Godley, B.J. (1998). Molecular Resolution of Marine Turtle Stock composition in fishery bycatch: a case study in the Mediterranean. Molecular Ecology, 7, 1529-1542.
Hancock, E.G. (1997). Insect infestation of Mediterranean marine turtle nests. Herpetological Review, 28(4), 190-191.
Godley, B.J. Kelly, A. Broderick, A.C. (1997). Marine turtle nesting in the Göksu Delta, Turkey, 1996. Marine Turtle Newsletter, 77, 17-19.
Godley, B.J. (1997). Observations of reproductive behaviour of male green turtles (Chelonia mydas) at a nesting beach in Cyprus. Chelonian Conservation and Biology, 2(4), 615-616.
Godley, B.J. (1996). Population and nesting ecology of the green turtle, Chelonia mydas, and loggerhead turtle, Caretta caretta, in northern Cyprus. Zoology in the Middle East, 13, 27-46.
Broderick, A.C. (1996). Turtles and Tourist Marketing: a British Perspective. Marine Turtle Newsletter, 74, 16-17.
Broderick, A.C. (1995). Northern Cyprus is critical habitat for Mediterranean turtles. Marine Turtle Newsletter, 69, 18-19.
Godley, B.J. (1994). Marine turtles in Northern Cyprus. Results from Glasgow University Expeditions 1992-1993. Marine Turtle Newsletter, 67, 8-11.
Broderick, A.C. (1992). Marine Turtles in Trinidad and Tobago. Marine Turtle Newsletter, 61, 15-18.
Chapters
Duncan E, Broderick A, Galloway T, Lindeque P, Godley B (2017). Investigating the Presence and Effects of Microplastics in Sea Turtles. In (Ed) Fate and Impact of Microplastics in Marine Ecosystems, Elsevier, 33-34.
Hawkes LA, Broderick AC, Godfrey MH, Godley BJ, Witt MJ (2014). The impacts of climate change on marine turtle reproductive success. In (Ed) Coastal Conservation, Cambridge University Press, 287-310.
Shuter JL, Broderick AC, Agnew DJ, Jonzen N, Godley BJ, Milner-Gulland EJ, Thirgood S (2011). Conservation and management of migratory species. In Milner-Gulland EJ, Fryxell JM, Sinclair ARE (Eds.)
Animal Migration, Oxford Univ Pr.
Abstract:
Conservation and management of migratory species
Abstract.
Reports
Broderick, A.C. Campbell, L.M. Ranger, S. (2004). An Assessment of the Status and Exploitation of Marine Turtles in the UK Overseas Territories in the Wider Caribbean. Final Project Report to the Department of Environment, Food and Rural Affairs and the Foreign and Commonwealth Office.
Publications by year
In Press
Witt M, Godley B, Pikesley S (In Press). A novel approach to estimate the distribution, density and at-sea risks of a
centrally-placed mobile marine vertebrate. Biological Conservation
Varela MR, Patricio AR, Anderson K, Broderick AC, DeBell L, Hawkes LA, Tilley D, Snape R, Westoby MJ, Godley BJ, et al (In Press). Assessing climate change associated sea level rise impacts on sea turtle nesting beaches using drones, photogrammetry and a novel GPS system. Global Change Biology
Duncan E, Arrowsmith JA, Bain CE, Bowdery H, Broderick A, Chalmers T, Fuller WJ, Galloway T, Lee JH, Lindeque PK, et al (In Press). Diet-related selectivity of macroplastic ingestion in green turtles (Chelonia mydas) in the eastern Mediterranean. Scientific Reports
Weber SB, Richardson AJ, Brown J, Bolton M, Clark B, Godley B, Leat EHK, Oppel S, Soetaert KER, Weber N, et al (In Press). Direct evidence of a prey depletion ‘halo’ surrounding a pelagic predator colony. Proceedings of the National Academy of Sciences of USA
Patricio AR, Formia A, Barbosa C, Broderick AC, Bruford M, Carreras C, Catry P, Ciofi C, Regalla A, Godley BJ, et al (In Press). Dispersal of green turtles from Africa’s largest rookery assessed through genetic markers. Marine Ecology Progress Series
Bjorndal KA, Bolten AB, Chaloupka M, Saba VS, Bellini C, Marcovaldi MAG, Santos AJ, Bortolon LFW, Meylan AB, Meylan PA, et al (In Press). Ecological regime shift drives declining growth rates of sea turtles throughout the West Atlantic. Global Change Biology
Rees AF, Carreras C, Broderick AC, Margaritoulis D, Stringell T, Godley BJ (In Press). Linking loggerhead locations: using multiple methods to determine the origin of sea turtles in feeding grounds. Marine Biology
Stevens M, Broderick AC, Godley BJ, Lown AE, Troscianko J, Weber N, Weber SB (In Press). Phenotype-Environment Matching in Sand Fleas. Biology Letters
Stringell TB, Clerveaux WV, Godley BJ, Phillips Q, Ranger S, Richardson PB, Sanghera A, Broderick AC (In Press). Protecting the breeders: research informs legislative change in a marine turtle fishery.
Biodiversity and ConservationAbstract:
Protecting the breeders: research informs legislative change in a marine turtle fishery
Marine turtles are sensitive to harvesting because of life-cycle traits such as longevity, late maturity and natal philopatry. The take of nesting females is of conservation concern because they are key to population maintenance and has led to global efforts to protect this life stage. In the Turks and Caicos Islands (TCI; a UK Overseas Territory in the Caribbean), previous turtle fishery legislation protected nesting turtles on the beach but not in the water, where turtles over a minimum size were subject to legal take. In a 2-year study, we undertook nesting beach and in-water surveys, molecular analyses, satellite tracking and collation of fisheries landing data to investigate the populations of green
(Chelonia mydas) and hawksbill (Eretmochelys imbricata) turtles in the TCI and its turtle fishery. Adults were frequently taken in one of the region’s largest legal and artisanal turtle fisheries. We suggest that nesting populations in the TCI, which contain genetically unique
haplotypes, have diminished since the 1980s, likely as a result of the harvest of adults. Using these multiple lines of evidence, we highlight the inadequacies of the former fishery regulations and propose specific legislative amendments, which, as a result of this study, were implemented on 1 July 2014 by the TCI government. With good enforcement, these measures will protect adults breeding in the TCI and those from nesting rookeries in the region that use the waters of the TCI, improve the management of this fishery, and safeguard fisher livelihoods.
Abstract.
2024
Palmer JL, Armstrong C, Akbora HD, Beton D, Çağlar Ç, Godley BJ, Metcalfe K, Özkan M, Snape RTE, Broderick AC, et al (2024). Behavioural patterns, spatial utilisation and landings composition of a small-scale fishery in the eastern Mediterranean.
Fisheries Research,
269Abstract:
Behavioural patterns, spatial utilisation and landings composition of a small-scale fishery in the eastern Mediterranean
Small-scale fisheries (SSFs) are crucial for global food security and cultural heritage, however, information on their spatial distribution and practices are often lacking, precluding effective management and mitigation of ecological impacts. This is acutely the case in the eastern Mediterranean basin, where, despite concerns being raised regarding the magnitude of marine turtle bycatch in SSFs over two decades ago, a poor understanding of the fishery persists. To address this knowledge gap, we characterised the SSF fleet of Northern Cyprus through a combination of onboard observations, fisher self-reporting and vessel tracking to provide the first comprehensive overview of the fishery. Northern Cyprus had a fleet size, standardised by coastline length, ranked 14th of 23 Mediterranean fleets assessed, with an estimated 49542 and 57198 fishing days in total in 2020 and 2021, respectively. Vessels operated mainly over the continental shelf (< 200 m) and were predominantly active during the night (53.2%, n = 573378 locations). Clear crepuscular peaks in vessel activity and gear deployment raise concerns over spatiotemporal overlap with vulnerable species, even within MPAs previously established to protect them. Fishers (n = 1296 fishing operations) predominantly utilised static and demersal gear types including gill nets (35.0%), trammel nets (27.3%), trammel and gill nets combined (20.3%), demersal longlines (17.0%) and handlines (0.5%). Landings composition was highly diverse with a minimum of 238 different taxa identified, including, but not limited to, 123 species of bony fish, 22 elasmobranch species, 3 marine turtle species and 12 mollusc species of which 18.6% are considered threatened either at a Mediterranean or global scale. However, over 70.0% of total landing mass was comprised of only five species including bogue (Boops boops), picarel (Spicara smaris), blotched picarel (Spicara maena), greater amberjack (Seriola dumerili) and Mediterranean parrotfish (Sparisoma cretense). As the most up to date and detailed understanding of this fishery's operating behaviours, our research compares the results obtained from onboard observer and self-reporting fisher sampling methodologies and discusses the caveats of each and identifies potential opportunities to adapt existing practices and MPAs to improve long-term sustainability of the fishery, whilst maintaining its socio-economic benefits to the local community.
Abstract.
2023
Fuentes MMPB, Santos AJB, Abreu-Grobois A, Briseño-Dueñas R, Al-Khayat J, Hamza S, Saliba S, Anderson D, Rusenko KW, Mitchell NJ, et al (2023). Adaptation of sea turtles to climate warming: Will phenological responses be sufficient to counteract changes in reproductive output?.
Glob Chang BiolAbstract:
Adaptation of sea turtles to climate warming: Will phenological responses be sufficient to counteract changes in reproductive output?
Sea turtles are vulnerable to climate change since their reproductive output is influenced by incubating temperatures, with warmer temperatures causing lower hatching success and increased feminization of embryos. Their ability to cope with projected increases in ambient temperatures will depend on their capacity to adapt to shifts in climatic regimes. Here, we assessed the extent to which phenological shifts could mitigate impacts from increases in ambient temperatures (from 1.5 to 3°C in air temperatures and from 1.4 to 2.3°C in sea surface temperatures by 2100 at our sites) on four species of sea turtles, under a "middle of the road" scenario (SSP2-4.5). Sand temperatures at sea turtle nesting sites are projected to increase from 0.58 to 4.17°C by 2100 and expected shifts in nesting of 26-43 days earlier will not be sufficient to maintain current incubation temperatures at 7 (29%) of our sites, hatching success rates at 10 (42%) of our sites, with current trends in hatchling sex ratio being able to be maintained at half of the sites. We also calculated the phenological shifts that would be required (both backward for an earlier shift in nesting and forward for a later shift) to keep up with present-day incubation temperatures, hatching success rates, and sex ratios. The required shifts backward in nesting for incubation temperatures ranged from -20 to -191 days, whereas the required shifts forward ranged from +54 to +180 days. However, for half of the sites, no matter the shift the median incubation temperature will always be warmer than the 75th percentile of current ranges. Given that phenological shifts will not be able to ameliorate predicted changes in temperature, hatching success and sex ratio at most sites, turtles may need to use other adaptive responses and/or there is the need to enhance sea turtle resilience to climate warming.
Abstract.
Author URL.
O’Keefe M, Bengil EGT, Palmer JL, Beton D, Çağlar Ç, Godley BJ, Özkan M, Snape RTE, Broderick AC (2023). Diversity and distribution of elasmobranchs in the coastal waters of Cyprus: using bycatch data to inform management and conservation. Frontiers in Marine Science, 10
Kaska A, Koç G, Sözbilen D, Salih D, Glidan A, Elsowayeb AA, Saied A, Margaritoulis D, Theodorou P, Rees A, et al (2023). Increased sample size provides novel insights into population structure of Mediterranean loggerhead sea turtles. Conservation Genetics Resources, 15(1-2), 67-75.
Alameri H (2023). Marine turtles: a comprehensive review and an assessment of climate change-associated impacts in Abu Dhabi, United Arab Emirates.
Abstract:
Marine turtles: a comprehensive review and an assessment of climate change-associated impacts in Abu Dhabi, United Arab Emirates
Climate change threatens marine turtles that depend on beaches for nesting with temperature changes affecting embryonic development and sex determination. Sea level rise may destroy their nesting habitats, and warming temperatures may cause complete development failure and imbalanced sex ratios. It is critical, therefore, to understand the likely climate change impacts to ensure mitigation is undertaken. It is particularly useful to examine climate change impacts in areas already facing extreme environmental conditions. The northwestern Indian Ocean (NWIO) is a relatively understudied region regarding marine turtles. Key knowledge gaps helped shape the main aims of this thesis, and these are:
1. to understand the status of marine turtles in the NWIO region from published material and regional expert elicitation;
2. to analyze 20 years of available data on marine turtles in Abu Dhabi, United Arab Emirates;
3. to investigate nest temperatures in Abu Dhabi to estimate primary sex ratios and the likely impact of global climate change on population dynamics and conservation, and;
4. to estimate the level of nest inundation that might result from forecast sea level rises associated with climate change.
My key findings were that:
1. Significant research and conservation efforts have focused on marine turtles across the NWIO region. I identified major threats, knowledge gaps, impediments to practical conservation, and strengths and opportunities towards creating a knowledge base for future research.
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2. The long-term marine turtle conservation plan in Abu Dhabi Emirate covers nesting ecology, foraging, mortality investigations, and rehabilitation initiatives. The mean estimate of hawksbill turtle clutches per year was 220 while the foraging population of all species and all sizes found in the emirate is 5,550–7,488 individuals. The majority of mortality was due to drowning in abandoned nets. Further research, including additional in-water foraging studies, population structure, and comprehensive nesting trends, is vital.
3. Primary sex ratios of hawksbill hatchlings are prone to be highly female-biased (> 80 % female), and only nests in the first three weeks of the breeding season were likely to have produced male hatchlings.
4. Beaches at major nesting islands will be profoundly affected by inundation due to sea level rise, however, the core nesting areas will remain as potential nesting sites.
I propose additional management approaches under each aspect and a detailed list of research priorities for Abu Dhabi
Abstract.
Mazaris AD, Dimitriadis C, Papazekou M, Schofield G, Doxa A, Chatzimentor A, Turkozan O, Katsanevakis S, Lioliou A, Abalo-Morla S, et al (2023). Priorities for Mediterranean marine turtle conservation and management in the face of climate change.
J Environ Manage,
339Abstract:
Priorities for Mediterranean marine turtle conservation and management in the face of climate change.
As climate-related impacts threaten marine biodiversity globally, it is important to adjust conservation efforts to mitigate the effects of climate change. Translating scientific knowledge into practical management, however, is often complicated due to resource, economic and policy constraints, generating a knowledge-action gap. To develop potential solutions for marine turtle conservation, we explored the perceptions of key actors across 18 countries in the Mediterranean. These actors evaluated their perceived relative importance of 19 adaptation and mitigation measures that could safeguard marine turtles from climate change. of importance, despite differences in expertise, experience and focal country, the perceptions of researchers and management practitioners largely converged with respect to prioritizing adaptation and mitigation measures. Climate change was considered to have the greatest impacts on offspring sex ratios and suitable nesting sites. The most viable adaptation/mitigation measures were considered to be reducing other pressures that act in parallel to climate change. Ecological effectiveness represented a key determinant for implementing proposed measures, followed by practical applicability, financial cost, and societal cost. This convergence in opinions across actors likely reflects long-standing initiatives in the Mediterranean region towards supporting knowledge exchange in marine turtle conservation. Our results provide important guidance on how to prioritize measures that incorporate climate change in decision-making processes related to the current and future management and protection of marine turtles at the ocean-basin scale, and could be used to guide decisions in other regions globally. Importantly, this study demonstrates a successful example of how interactive processes can be used to fill the knowledge-action gap between research and management.
Abstract.
Author URL.
de Kock W, Mackie M, Ramsøe M, Allentoft ME, Broderick AC, Haywood JC, Godley BJ, Snape RTE, Bradshaw PJ, Genz H, et al (2023). Threatened North African seagrass meadows have supported green turtle populations for millennia.
Proceedings of the National Academy of Sciences,
120(30).
Abstract:
Threatened North African seagrass meadows have supported green turtle populations for millennia
. “Protect and restore ecosystems and biodiversity”
. is the second official aim of the current UN Ocean Decade (2021 to 2030) calling for the identification and protection of critical marine habitats. However, data to inform policy are often lacking altogether or confined to recent times, preventing the establishment of long-term baselines. The unique insights gained from combining bioarchaeology (palaeoproteomics, stable isotope analysis) with contemporary data (from satellite tracking) identified habitats which sea turtles have been using in the Eastern Mediterranean over five millennia. Specifically, our analysis of archaeological green turtle (
. Chelonia mydas
. ) bones revealed that they likely foraged on the same North African seagrass meadows as their modern-day counterparts. Here, millennia-long foraging habitat fidelity has been directly demonstrated, highlighting the significance (and long-term dividends) of protecting these critical coastal habitats that are especially vulnerable to global warming. We highlight the potential for historical ecology to inform policy in safeguarding critical marine habitats.
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Abstract.
Collins C, Letessier TB, Benaragama A, Broderick A, Wijesundara I, Wijetunge D, Nuno A (2023). Valuable bycatch: Eliciting social importance of sharks in Sri Lanka through value chain analysis.
Marine Policy,
157Abstract:
Valuable bycatch: Eliciting social importance of sharks in Sri Lanka through value chain analysis
Decades of unsustainable fishing have caused widespread declines in shark populations leading to calls for increased management and policy. To design successful measures, an understanding of the social context and drivers for trade is needed. This study uses a value chain approach in Sri Lanka, where shark landings have declined rapidly, to map shark trade actors, ascertain determinants of price of shark meat and determine wider social value of shark products. Data was collected over one year from surveys of sales events (n = 630), and semi-structured interviews (n = 24), at two sites on the south and west coasts. We identify a dynamic, flexible supply chain with a small number of specialised stakeholders that may alternate roles depending on factors such as supply of sharks. Sharks were the primary income source for most (71%, n = 17) and 25% (n = 6) reported no alternative income sources. Trade was dominated by dried shark meat in the domestic market, and demand shaped by its perceived nutritional benefits and taste. Identification of species was difficult, and shark meat was primarily sold as size categories, however, whether or not shark was sold as blue shark (Prionace glauca) significantly impacted price reportedly due to lower international demand for their fins. Stakeholders perceived substantial drops in shark landings and trade > 10 years ago. We show that, within Sri Lanka, shark products represent a nexus of two dramatically different markets: high-value fins for their export markets and low to medium-value meat important for domestic earnings. The presence of dried products reportedly increases resilience of shark trade to socio-ecological shocks. Disentangling the relative social importance of these products, through product-specific and species-specific data is vital for a move towards predictive management that is capable of robust outcomes.
Abstract.
2022
DiMatteo A, Cañadas A, Roberts J, Sparks L, Panigada S, Boisseau O, Moscrop A, Fortuna CM, Lauriano G, Holcer D, et al (2022). Basin-wide estimates of loggerhead turtle abundance in the Mediterranean Sea derived from line transect surveys. Frontiers in Marine Science, 9
Al Ameri H, Al Harthi S, Al Kiyumi A, Al Sariri T, Al-Zaidan A, Antonopoulou M, Broderick A, Chatting M, Das H, Hesni M, et al (2022). Biology and conservation of marine turtles in the northwestern Indian Ocean: a review. Endangered Species Research, 48, 67-86.
Al Ameri H, Al Harthi S, Al Kiyumi A, Al Sariri T, Al-Zaidan A, Antonopoulou M, Broderick A, Chatting M, Das H, Hesni M, et al (2022). CORRIGENDUM: Biology and conservation of marine turtles in the northwestern Indian Ocean: a review. Endangered Species Research, 48
Kaska A, Koç G, Sözbilen D, Diryaq S, Glidan A, Elsowayeb AA, Saied A, Margaritoulis D, Theodorou P, Rees AF, et al (2022). Increased Sample Size Proved More Insights for the Population Structure of Mediterranean Loggerhead Sea Turtles.
Kaska A, Koç G, Sözbilen D, Diryaq S, Glidan A, Elsowayeb AA, Saied A, Margaritoulis D, Theodorou P, Rees AF, et al (2022). Increased Sample Size Proved More Insights for the Population Structure of Mediterranean Loggerhead Sea Turtles.
de Geer C, Bourjea J, Broderick A, Dalleau M, Fernandes R, Harris L, Inteca G, Kiponda F, Louro C, Mortimer J, et al (2022). Marine turtles of the African east coast: current knowledge and priorities for conservation and research. Endangered Species Research, 47, 297-331.
Snape RTE, Beton D, Davey S, Godley BJ, Haywood J, Omeyer LCM, Ozkan M, Broderick AC (2022). Mediterranean green turtle population recovery increasingly depends on Lake Bardawil, Egypt.
Global Ecology and Conservation,
40Abstract:
Mediterranean green turtle population recovery increasingly depends on Lake Bardawil, Egypt
To assign conservation status to a population, its size, trends, and distribution must be estimated. The Mediterranean green turtle population has shown signs of recovering over the past decade, likely in response to nest protection, but satellite tracking suggests adult foraging remains largely restricted to only a few key sites in the eastern Mediterranean. Previous research suggested that the majority of green turtles nesting at an important rookery in Cyprus, forage in Lake Bardawil, Egypt making an observed population increase dependent on this important site, which is under a high degree of anthropogenic maintenance. Here we provide new data that further demonstrates the importance of Lake Bardawil to green turtles that nest at other major rookeries on Cyprus, in the Karpaz Peninsula, with 74 % of satellite tracked females (n = 19) migrating to this key site. We also report on the first systematic nest counts for this area in over two decades and identify the inter-nesting habitat used by females nesting at these important beaches on the north and south coasts of the Peninsula. Comparing the oldest available 3-year nest count averages (1993–1995), with nest counts undertaken as part of this study (2017–2019), mean annual nest numbers increased from 186 to 554, an increase of 198 %. Our data confirm the continued importance of these beaches for the Mediterranean green turtle population and underscore the reliance of this endangered population on a man-made lagoon for recent increases in clutch counts at monitored beaches. The results highlight the utility of satellite telemetry to inform conservation status assessments and establishing conservation at both nesting and foraging sites across the population.
Abstract.
Kot CY, Åkesson S, Alfaro‐Shigueto J, Amorocho Llanos DF, Antonopoulou M, Balazs GH, Baverstock WR, Blumenthal JM, Broderick AC, Bruno I, et al (2022). Network analysis of sea turtle movements and connectivity: a tool for conservation prioritization.
Diversity and Distributions,
28(4), 810-829.
Abstract:
Network analysis of sea turtle movements and connectivity: a tool for conservation prioritization
AbstractAimUnderstanding the spatial ecology of animal movements is a critical element in conserving long‐lived, highly mobile marine species. Analyzing networks developed from movements of six sea turtle species reveals marine connectivity and can help prioritize conservation efforts.LocationGlobal.MethodsWe collated telemetry data from 1235 individuals and reviewed the literature to determine our dataset's representativeness. We used the telemetry data to develop spatial networks at different scales to examine areas, connections, and their geographic arrangement. We used graph theory metrics to compare networks across regions and species and to identify the role of important areas and connections.ResultsRelevant literature and citations for data used in this study had very little overlap. Network analysis showed that sampling effort influenced network structure, and the arrangement of areas and connections for most networks was complex. However, important areas and connections identified by graph theory metrics can be different than areas of high data density. For the global network, marine regions in the Mediterranean had high closeness, while links with high betweenness among marine regions in the South Atlantic were critical for maintaining connectivity. Comparisons among species‐specific networks showed that functional connectivity was related to movement ecology, resulting in networks composed of different areas and links.Main conclusionsNetwork analysis identified the structure and functional connectivity of the sea turtles in our sample at multiple scales. These network characteristics could help guide the coordination of management strategies for wide‐ranging animals throughout their geographic extent. Most networks had complex structures that can contribute to greater robustness but may be more difficult to manage changes when compared to simpler forms. Area‐based conservation measures would benefit sea turtle populations when directed toward areas with high closeness dominating network function. Promoting seascape connectivity of links with high betweenness would decrease network vulnerability.
Abstract.
Wu NC, Rusli MU, Broderick AC, Barneche DR (2022). Size scaling of sea turtle reproduction may reconcile fundamental ecology and conservation strategies at the global scale.
Global Ecology and Biogeography,
31(7), 1277-1289.
Abstract:
Size scaling of sea turtle reproduction may reconcile fundamental ecology and conservation strategies at the global scale
Aim: the body size of marine megafauna can influence population dynamics because larger females have disproportionally greater reproductive output. We explored how this size scaling relationship can affect predictions of population size structure in nesting sea turtles by combining a phylogenetically controlled meta-analysis with a long-term field nesting survey. Location: Global (meta-analysis) and Malaysia (field survey). Time period: Present. Major taxa studied: Sea turtles. Methods: We extracted body size and reproductive parameters of all sea turtle species from the literature and estimated the reproductive-energy output using allometric models. We then examined the relationship between body size and the proportion of protected nesting beaches by country as an indicator of conservation efforts on body size. Long-term monitoring (1993–2019) of body size and nesting data on green turtles (Chelonia mydas) from Redang Island (Malaysia) was used to examine temporal changes in body size and fecundity and to test whether the size scaling of fecundity was isometric (linear) or allometric (curvilinear). Results: We show that the total reproductive-energy output of larger nesting females was, on average, disproportionately greater in all sea turtle species. We found no strong correlations for countries with a higher proportion of protected nesting sites with female size. Finally, we showed that scaling-derived calculations of population-level yearly reproductive output in the green turtle population from Redang Island were more accurate when using a hyperallometric (rather than an isometric) relationship at the individual level. Main conclusions: Understanding ecosystem function and conservation effort requires accurate predictions of population trends. Our findings highlight the necessity to account for scaling effects of body size in predicting anthropogenically mediated population shifts, and the need to protect large females in order to facilitate effective population replenishment.
Abstract.
Gough C, Ateweberhan M, Godley BJ, Harris A, Le Manach F, Zafindranosy E, Broderick AC (2022). Temporal Change and Fishing Down Food Webs in Small-Scale Fisheries in Morondava, Madagascar. Frontiers in Marine Science, 9
Barbanti A, Blumenthal JM, Broderick AC, Godley BJ, Prat-Varela A, Turmo M, Pascual M, Carreras C (2022). The architecture of assisted colonisation in sea turtles: building new populations in a biodiversity crisis.
Nat Commun,
13(1).
Abstract:
The architecture of assisted colonisation in sea turtles: building new populations in a biodiversity crisis.
Due to changing environmental conditions, many species will have to migrate or occupy new suitable areas to avoid potential extinction in the current biodiversity crisis. Long-lived animals are especially vulnerable and ex-situ conservation actions can provide solutions through assisted colonisations. However, there is little empirical evidence on the process of founding new populations for such species or the feasibility of assisted colonisations as a viable conservation measure. Here, we combined genetics with reproductive data to study the rise of two wild populations of green turtles (Chelonia mydas) in the Cayman Islands as a possible outcome of a reintroduction program started 50 years ago. We show that both populations are highly related to the captive population but rapidly diverged due to genetic drift. Individuals from the reintroduced populations showed high levels of nest fidelity, within and across nesting seasons, indicating that philopatry may help reinforce the success of new populations. Additionally, we show that reintroduction from captive populations has not undermined the reproductive fitness of first generation individuals. Sea turtle reintroduction programs can, therefore, establish new populations but require scientific evaluation of costs and benefits and should be monitored over time to ensure viability in the long-term.
Abstract.
Author URL.
2021
Blumenthal JM, Hardwick JL, Austin TJ, Broderick AC, Chin P, Collyer L, Ebanks-Petrie G, Grant L, Lamb LD, Olynik J, et al (2021). Cayman Islands Sea Turtle Nesting Population Increases over 22 Years of Monitoring.
Frontiers in Marine Science,
8Abstract:
Cayman Islands Sea Turtle Nesting Population Increases over 22 Years of Monitoring
Given differing trajectories of sea turtle populations worldwide, there is a need to assess and report long-term population trends and determine which conservation strategies are effective. In this study, we report on sea turtle nest monitoring in the Cayman Islands over a 22-year period. We found that green (Chelonia mydas) and loggerhead (Caretta caretta) nest numbers increased significantly across the three islands since monitoring began in 1998, but that hawksbill nest numbers remained low with a maximum of 13 nests recorded in a season. Comparing the first 5 years of nest numbers to the most recent 5 years, the greatest percentage increase in green turtle nests was in Grand Cayman from 82 to 1,005 nests (1,126%), whereas the greatest percentage increase for loggerhead turtle nests was in Little Cayman from 10 to 290 nests (3,800%). A captive breeding operation contributed to the increase in the Grand Cayman green turtle population, however, loggerhead turtles were never captive-bred, and these populations began to increase after a legal traditional turtle fishery became inactive in 2008. Although both species have shown significant signs of recovery, populations remain at a fragment of their historical level and are vulnerable to threats. Illegal harvesting occurs to this day, with multiple females taken from nesting beaches each year. For nests and hatchlings, threats include artificial lighting on nesting beaches, causing hatchlings to misorient away from the sea, and inundation of nests by seawater reducing hatch success. The impacts of lighting were found to increase over the monitoring period. Spatial data on nest distribution was used to identify critical nesting habitat for green and loggerhead turtles and is used by the Cayman Islands Department of Environment to facilitate remediation of threats related to beachside development and for targeted future management efforts.
Abstract.
Palmer JL, Beton D, Çiçek BA, Davey S, Duncan EM, Fuller WJ, Godley BJ, Haywood JC, Hüseyinoğlu MF, Omeyer LCM, et al (2021). Dietary analysis of two sympatric marine turtle species in the eastern Mediterranean.
Marine Biology,
168(6).
Abstract:
Dietary analysis of two sympatric marine turtle species in the eastern Mediterranean
AbstractDietary studies provide key insights into threats and changes within ecosystems and subsequent impacts on focal species. Diet is particularly challenging to study within marine environments and therefore is often poorly understood. Here, we examined the diet of stranded and bycaught loggerhead (Caretta caretta) and green turtles (Chelonia mydas) in North Cyprus (35.33° N, 33.47° E) between 2011 and 2019. A total of 129 taxa were recorded in the diet of loggerhead turtles (n = 45), which were predominantly carnivorous (on average 72.1% of dietary biomass), foraging on a large variety of invertebrates, macroalgae, seagrasses and bony fish in low frequencies. Despite this opportunistic foraging strategy, one species was particularly dominant, the sponge Chondrosia reniformis (21.5%). Consumption of this sponge decreased with increasing turtle size. A greater degree of herbivory was found in green turtles (n = 40) which predominantly consumed seagrasses and macroalgae (88.8%) with a total of 101 taxa recorded. The most dominant species was a Lessepsian invasive seagrass, Halophila stipulacea (31.1%). This is the highest percentage recorded for this species in green turtle diet in the Mediterranean thus far. With increasing turtle size, the percentage of seagrass consumed increased with a concomitant decrease in macroalgae. Seagrass was consumed year-round. Omnivory occurred in all green turtle size classes but reduced in larger turtles (> 75 cm CCL) suggesting a slow ontogenetic dietary shift. Macroplastic ingestion was more common in green (31.6% of individuals) than loggerhead turtles (5.7%). This study provides the most complete dietary list for marine turtles in the eastern Mediterranean.
Abstract.
Collins C (2021). Human dimensions of non-compliance in a large-scale Marine Protected Area.
Abstract:
Human dimensions of non-compliance in a large-scale Marine Protected Area
Achieving compliance with management and policies is vital for conservation success. As a human behaviour, managing non-compliance requires understanding of social factors of systems that are inherently social-ecological in nature. However, across marine conservation there remains key gaps in understanding of incentives for non-compliance, and social context of perpetrators, including for Marine Protected Areas (MPAs). Global expansion of MPA coverage has been substantially bolstered by creation of large-scale marine protected areas (LSMPAs, >100,000 km2), which offer important conservation successes such as encompassing holistic ecological systems. Yet, LSMPAs have been criticised for a lack of attention paid to associated social factors and outcomes, which some have connected with the persistence of non-compliance within many LSMPAs. Given their intended keystone role in marine conservation, addressing these criticisms is vital (Chapter 1). This thesis studied non-compliance by the Sri Lankan offshore fleet in the British Indian Ocean Territory (BIOT), a large (640,000km2) MPA located in the central Indian Ocean. Data collected within Sri Lankan fishing communities using social science research methods were used to describe fishing behaviour and non-compliance within this fleet. Current knowledge of illegal fishing within BIOT taken from enforcement of the MPA is reviewed within the context of fieldwork data (Chapter 2). We characterised similarities of non-compliant vessels and, using social network analysis, identified social ties between 66% of illegal vessels. These findings highlight the potential of adapting policy to target specific sectors of the fleet and for localised drivers of non-compliance. Participatory mapping techniques identified the broad spatial footprint of the fleet across the Indian Ocean and found 62% may frequent foreign countries waters illegally (Chapter 3). Perceptions of high populations of sharks within foreign waters were identified as a key driver, due to their high economic value and decreasing regional populations. Results highlighted the economic importance of sharks, suggesting they provide income for 74% of the surveyed vessels. Using value chain analysis, the economic importance of sharks within Sri Lanka was investigated (Chapter 4). Supply chains for shark products were mapped, and reliance on shark products was explored, including describing factors that determine price of landed sharks. On average, blue sharks (Prionace glauca) fetched lower prices than other landed species, including those of conservation concern, highlighting potential species-specific differences in economic incentives for targeting sharks. Sri Lankan national shark policy and management, specifically the ban on fishing thresher sharks (Alopiidae), was examined to determine effectiveness of existing measures (Chapter 5). The interaction of perceptions and impacts of the ban with compliance were explored. Key learnings were identified, including increasing stakeholder engagement and communication when introducing shark conservation policies. Finally, data and findings are synthesised within the context of existing national and regional management and policy to identify recommendations to mitigate non-compliance (Chapter 6). Overall, a more nuanced approach to LSMPA management, that investigates alternatives to purely sanctions-based models, is advocated for. Further, the potential benefits of adapting management based on understanding of social drivers gathered directly from perpetrators of non-compliance is highlighted.
Abstract.
Collins C (2021). Human dimensions of non-compliance in a large-scale Marine Protected Area.
Abstract:
Human dimensions of non-compliance in a large-scale Marine Protected Area
Achieving compliance with management and policies is vital for conservation success. As a human behaviour, managing non-compliance requires understanding of social factors of systems that are inherently social-ecological in nature. However, across marine conservation there remains key gaps in understanding of incentives for non-compliance, and social context of perpetrators, including for Marine Protected Areas (MPAs). Global expansion of MPA coverage has been substantially bolstered by creation of large-scale marine protected areas (LSMPAs, >100,000 km2), which offer important conservation successes such as encompassing holistic ecological systems. Yet, LSMPAs have been criticised for a lack of attention paid to associated social factors and outcomes, which some have connected with the persistence of non-compliance within many LSMPAs. Given their intended keystone role in marine conservation, addressing these criticisms is vital (Chapter 1). This thesis studied non-compliance by the Sri Lankan offshore fleet in the British Indian Ocean Territory (BIOT), a large (640,000km2) MPA located in the central Indian Ocean. Data collected within Sri Lankan fishing communities using social science research methods were used to describe fishing behaviour and non-compliance within this fleet. Current knowledge of illegal fishing within BIOT taken from enforcement of the MPA is reviewed within the context of fieldwork data (Chapter 2). We characterised similarities of non-compliant vessels and, using social network analysis, identified social ties between 66% of illegal vessels. These findings highlight the potential of adapting policy to target specific sectors of the fleet and for localised drivers of non-compliance. Participatory mapping techniques identified the broad spatial footprint of the fleet across the Indian Ocean and found 62% may frequent foreign countries waters illegally (Chapter 3). Perceptions of high populations of sharks within foreign waters were identified as a key driver, due to their high economic value and decreasing regional populations. Results highlighted the economic importance of sharks, suggesting they provide income for 74% of the surveyed vessels. Using value chain analysis, the economic importance of sharks within Sri Lanka was investigated (Chapter 4). Supply chains for shark products were mapped, and reliance on shark products was explored, including describing factors that determine price of landed sharks. On average, blue sharks (Prionace glauca) fetched lower prices than other landed species, including those of conservation concern, highlighting potential species-specific differences in economic incentives for targeting sharks. Sri Lankan national shark policy and management, specifically the ban on fishing thresher sharks (Alopiidae), was examined to determine effectiveness of existing measures (Chapter 5). The interaction of perceptions and impacts of the ban with compliance were explored. Key learnings were identified, including increasing stakeholder engagement and communication when introducing shark conservation policies. Finally, data and findings are synthesised within the context of existing national and regional management and policy to identify recommendations to mitigate non-compliance (Chapter 6). Overall, a more nuanced approach to LSMPA management, that investigates alternatives to purely sanctions-based models, is advocated for. Further, the potential benefits of adapting management based on understanding of social drivers gathered directly from perpetrators of non-compliance is highlighted.
Abstract.
Omeyer LCM, Stokes KL, Beton D, Çiçek BA, Davey S, Fuller WJ, Godley BJ, Sherley RB, Snape RTE, Broderick AC, et al (2021). Investigating differences in population recovery rates of two sympatrically nesting sea turtle species.
Animal Conservation,
24(5), 832-846.
Abstract:
Investigating differences in population recovery rates of two sympatrically nesting sea turtle species
AbstractEstimating life‐history traits and understanding their variation underpins the management of long‐lived, migratory animals, while knowledge of recovery dynamics can inform the management of conservation‐dependent species. Using a combination of nest counts and individual‐based life‐history data collected since 1993, we explore the drivers underlying contrasting population recovery rates of sympatrically nesting loggerhead (Caretta caretta) and green (Chelonia mydas) turtles in North Cyprus. We found that nest counts of loggerhead and green turtles from 28 beaches across the island increased by 46% and 162%, respectively over the past 27 years. A Bayesian state‐space model revealed that, at our individual‐based monitoring site, nesting of green turtles increased annually at four times the rate of that of loggerhead turtles. Furthermore, we found that loggerhead turtles nesting at the individual‐based monitoring site had stable reproductive parameters and average adult survival for the species and are the smallest breeding adults globally. Based on results from multiple matrix model scenarios, we propose that higher mortality rates of individuals in all age classes (likely driven by differences in life history and interaction with fisheries), rather than low reproductive output, are impeding the recovery of this species. While the increase in green turtles is encouraging, the Mediterranean population is estimated to have around 3,400 adults and is restricted to the Eastern Basin. The recovery of loggerhead turtles is likely to be compromised until mortality rates in the region are adequately quantified and mitigated. As survival of immature individuals is a powerful driver for sea turtle population numbers, additional efforts should target management at pelagic and neritic foraging areas. Understanding threats faced by immature life stages is crucial to accurately parameterise population models and to target conservation actions for long‐lived marine vertebrates.
Abstract.
Beton D, Broderick AC, Godley BJ, Kolaç E, Ok M, Snape RTE (2021). New monitoring confirms regular breeding of the Mediterranean monk seal in Northern Cyprus.
ORYX,
55(4), 522-525.
Abstract:
New monitoring confirms regular breeding of the Mediterranean monk seal in Northern Cyprus
The Endangered Mediterranean monk seal Monachus monachus is one of the most threatened marine mammals. Across Cyprus, suitable habitat and presence of monk seals is well documented and, recently, camera-trap surveys in Southern Cyprus found there to be pupping. We present results of the first camera-trap surveys in Northern Cyprus spanning the pupping period. Four adult/subadults and three pups were identified in three of eight caves monitored with camera traps. One site on the north-west of the island supported at least three adult/subadult seals and pupping occurred there in 3 consecutive years. The breeding and resting sites identified require urgent conservation to manage threats of disturbance, coastal development and fisheries bycatch. To determine the size of this population, a long-term survey with greater and more continuous coverage is required.
Abstract.
Collins C, Nuno A, Benaragama A, Broderick A, Wijesundara I, Wijetunge D, Letessier TB (2021). Ocean-scale footprint of a highly mobile fishing fleet: Social-ecological drivers of fleet behaviour and evidence of illegal fishing.
People and Nature,
3(3), 740-755.
Abstract:
Ocean-scale footprint of a highly mobile fishing fleet: Social-ecological drivers of fleet behaviour and evidence of illegal fishing
Managing the footprint of highly mobile fishing fleets is increasingly important due to continuing declines in fish populations. However, social-ecological drivers for fisher behaviour remain poorly understood for many fleets globally. Using the Sri Lankan fleet as a case study, we explored the role of social, environmental and policy drivers of effort distribution and illegal fishing. We used semi-structured interviews and participatory mapping with 95 fishers, combined with explanatory modelling (GLM) and multivariate statistics, including principal component analysis (PCA). Our findings highlighted the broad footprint (~3,800,000 km2) of this fleet, with fishing effort expended in high seas (53.9%), domestic (40.9%) and, illegally, in foreign waters (5.2%). Twenty-six per cent of fishers directly admitted to fishing illegally in foreign waters during interviews, whereas 62% of fishers indicated doing so during participatory mapping. GLMs explained underlying decisions of where to fish (36% of the total deviance in effort distribution) as a function of social variables (14%), notably distance from landing sites (13%), and environmental variables (11%), notably sea surface temperature (10%). Multivariate analysis revealed that individual fisher characteristics associated with illegal fishing, such as a level of reliance on sharks, vary across the fleet. The analysis of qualitative data suggested that the influence of interpersonal and community social networks and perceptions of higher catch value, particularly of sharks, may be important. Our approach demonstrated the utility of mixed methods research, including the collection of qualitative data, for creating a detailed understanding of spatial behaviour, including decisions of whether to fish illegally. Results highlighted the importance of adopting a social-ecological lens to investigate drivers for human behaviour and non-compliance with rules. We advocate for a nuanced approach to monitoring and managing of fleets, including investigating localised social drivers for illegal fishing and enhancing regional transparency in fleet monitoring. A free Plain Language Summary can be found within the Supporting Information of this article.
Abstract.
Nuno A, Matos L, Metcalfe K, Godley BJ, Broderick AC (2021). Perceived influence over marine conservation: Determinants and implications of empowerment.
Conservation Letters,
14(3).
Abstract:
Perceived influence over marine conservation: Determinants and implications of empowerment
Understanding empowerment is integral to facilitating sustainable use policies and requires assessing potential drivers. However, critical applications are rare in conservation. Using the island of Príncipe (São Tomé and Príncipe) as a case study, we undertook household surveys (N = 869) to assess potential drivers of psychological empowerment towards conservation, measured as the perceived abilities of people to individually or collectively influence marine conservation outcomes, accounting for gender. Law enforcement, collective influence, freedom of choice and action, environmental condition and living in coastal community were key variables for understanding perceived personal influence. In particular, no-fishing areas and raising awareness about sustainable practices were recommended by those with higher self-perceived influence. Such information on target groups and factors to promote is essential for facilitating empowerment towards conservation and laying robust foundations for resource comanagement, especially given the role communities can play in the face of limited state capacity and enforcement.
Abstract.
Duncan EM, Broderick AC, Critchell K, Galloway TS, Hamann M, Limpus CJ, Lindeque PK, Santillo D, Tucker AD, Whiting S, et al (2021). Plastic Pollution and Small Juvenile Marine Turtles: a Potential Evolutionary Trap.
FRONTIERS IN MARINE SCIENCE,
8 Author URL.
Collins C, Nuno A, Broderick A (2021). Understanding Persistent Non-compliance in a Remote, Large-Scale Marine Protected Area. Frontiers in Marine Science
2020
Colman LP, Lara PH, Bennie J, Broderick AC, de Freitas JR, Marcondes A, Witt MJ, Godley BJ (2020). Assessing coastal artificial light and potential exposure of wildlife at a national scale: the case of marine turtles in Brazil.
Biodiversity and Conservation,
29(4), 1135-1152.
Abstract:
Assessing coastal artificial light and potential exposure of wildlife at a national scale: the case of marine turtles in Brazil
AbstractCoastal areas provide critical nesting habitat for marine turtles. Understanding how artificial light might impact populations is key to guide management strategies. Here we assess the extent to which nesting populations of four marine turtle species—leatherback (Dermochelys coriacea), olive ridley (Lepidochelys olivacea), hawksbill (Eretmochelys imbricata) and two subpopulations of loggerhead (Caretta caretta) turtles—are exposed to light pollution across 604 km of the Brazilian coast. We used yearly night-time satellite images from two 5-year periods (1992–1996 and 2008–2012) from the US Air Force Defense Meteorological Satellite Programme (DMSP) to determine the proportion of nesting areas that are exposed to detectable levels of artificial light and identify how this has changed over time. Over the monitored time-frame, 63.7% of the nesting beaches experienced an increase in night light levels. Based on nest densities, we identified 54 reproductive hotspots: 62.9% were located in areas potentially exposed to light pollution. Light levels appeared to have a significant effect on nest densities of hawksbills and the northern loggerhead turtle stock, however high nest densities were also seen in lit areas. The status of all species/subpopulations has improved across the time period despite increased light levels. These findings suggest that (1) nest site selection is likely primarily determined by variables other than light and (2) conservation strategies in Brazil appear to have been successful in contributing to reducing impacts on nesting beaches. There is, however, the possibility that light also affects hatchlings in coastal waters, and impacts on population recruitment may take longer to fully manifest in nesting numbers. Recommendations are made to further this work to provide deeper insights into the impacts of anthropogenic light on marine turtles.
Abstract.
Gough CLA, Dewar KM, Godley BJ, Zafindranosy E, Broderick AC (2020). Evidence of Overfishing in Small-Scale Fisheries in Madagascar. Frontiers in Marine Science, 7
Haywood JC, Casale P, Freggi D, Fuller WJ, Godley BJ, Lazar B, Margaritoulis D, Rees AF, Shutler JD, Snape RT, et al (2020). Foraging ecology of Mediterranean juvenile loggerhead turtles: insights from C and N stable isotope ratios.
Marine Biology,
167(3).
Abstract:
Foraging ecology of Mediterranean juvenile loggerhead turtles: insights from C and N stable isotope ratios
AbstractBycatch is one of the key threats to juvenile marine turtles in the Mediterranean Sea. As fishing methods are regional or habitat specific, the susceptibility of marine turtles may differ according to inter- and intra-population variations in foraging ecology. An understanding of these variations is necessary to assess bycatch susceptibility and to implement region-specific management. To determine if foraging ecology differs with region, sex, and size of juvenile loggerhead turtles (Caretta caretta), stable isotope analysis of carbon and nitrogen was performed on 171 juveniles from a range of foraging regions across the central and eastern Mediterranean Sea. Isotope ratios differed with geographical region, likely due to baseline variations in δ13C and δ15N values. The absence of sex-specific differences suggests that within an area, all comparably sized animals likely exploit similar foraging strategies, and therefore, their susceptibility to fisheries threats will likely be similar. The isotope ratios of juveniles occupying the North East Adriatic and North Levantine basin increased with size, potentially due to increased consumption of more prey items at higher trophic levels from a more neritic source. Isotope ratios of juveniles with access to both neritic and oceanic habitats did not differ with size which is consistent with them consuming prey items from both habitats interchangeably. With foraging habitats exploited differently among size classes in a population, the susceptibility to fisheries interactions will likely differ with size; therefore, region-specific management approaches will be needed.
Abstract.
Godley BJ, Broderick AC, Colman LP, Formia A, Godfrey MH, Hamann M, Nuno A, Omeyer LCM, Patrício AR, Phillott AD, et al (2020). Reflections on sea turtle conservation. Oryx, 54(3), 287-289.
Doherty PD, Broderick AC, Godley BJ, Hart KA, Phillips Q, Sanghera A, Stringell TB, Walker JT, Richardson PB (2020). Spatial Ecology of Sub-Adult Green Turtles in Coastal Waters of the Turks and Caicos Islands: Implications for Conservation Management. Frontiers in Marine Science, 7
Haywood JC, Fuller WJ, Godley BJ, Margaritoulis D, Shutler JD, Snape RTE, Widdicombe S, Zbinden JA, Broderick AC (2020). Spatial ecology of loggerhead turtles: Insights from stable isotope markers and satellite telemetry.
Diversity and Distributions,
26(3), 368-381.
Abstract:
Spatial ecology of loggerhead turtles: Insights from stable isotope markers and satellite telemetry
Aim: Using a combination of satellite telemetry and stable isotope analysis (SIA), our aim was to identify foraging grounds of loggerhead turtles (Caretta caretta) at important rookeries in the Mediterranean, examine foraging ground fidelity, and across 25 years determine the proportion of nesting females recruiting from each foraging region to a major rookery in Cyprus. Location: Mediterranean Sea. Methods: Between 1993 and 2018, we investigated the spatial ecology of loggerhead turtles from rookeries in Cyprus and Greece using satellite telemetry (n = 55 adults) and SIA of three elements (n = 296). Results: Satellite telemetry from both rookeries revealed the main foraging areas as the Adriatic region (Cyprus: 4% of individuals, Greece: 55%), Tunisian Plateau (Cyprus: 16%, Greece: 40%) and the eastern Mediterranean (Cyprus: 80%, Greece: 5%). Combining satellite telemetry and SIA allowed 64% of all nesting females to be assigned to; the Adriatic region (Cyprus: 2%, Greece: 38.5%), Tunisian Plateau (Cyprus: 47%, Greece: 38.5%) and the eastern Mediterranean (Cyprus: 51%, Greece: 23%), which are markedly different to proportions obtained using satellite telemetry. The proportion of the Cyprus nesting cohort using each foraging region did not change significantly, with the exception that individuals foraging in the Adriatic region are only present in the Cyprus nesting population from 2012. Repeat satellite tracking (n = 3) and temporal consistency in isotope ratios (n = 36) of Cyprus females, strongly suggest foraging ground fidelity over multiple decades. Main conclusions: This study demonstrates the advantages of combining satellite telemetry and SIA to investigate spatial ecology at a population level. The importance of the Tunisian Plateau for foraging is demonstrated. This study indicates that females generally show high fidelity to foraging grounds and shows a potential recent shift to foraging in the Adriatic region for Cyprus females, while the importance of other regions persists across decades, thus providing baselines to develop and assess conservation strategies.
Abstract.
Haywood J (2020). THE SPATIAL ECOLOGY OF MEDITERRANEAN MARINE TURTLES: INSIGHTS FROM STABLE ISOTOPE ANALYSIS, SATELLITE TELEMETRY, AND ENVIRONMENTAL OBSERVATIONS.
Abstract:
THE SPATIAL ECOLOGY OF MEDITERRANEAN MARINE TURTLES: INSIGHTS FROM STABLE ISOTOPE ANALYSIS, SATELLITE TELEMETRY, AND ENVIRONMENTAL OBSERVATIONS
Understanding the spatial and foraging ecology of marine migrants is challenging, due to the vast distances travelled and the numerous habitats occupied within a dynamic seascape. Mediterranean marine turtles migrate thousands of kilometers and face numerous threats, including bycatch, in their marine realm. To help inform targeted conservation, this complex marine ecology must be better understood. This thesis focuses on Mediterranean loggerhead (Caretta caretta) and green turtles (Chelonia mydas). By complementing stable isotope analysis (SIA), satellite telemetry, and environmental observations, this thesis aims to enhance our understanding of the complexities of marine turtle spatial and foraging ecology, as well as determine how future climate conditions may influence their habitat use.
In Chapter 1, I introduce the importance of conserving marine migrants and discuss the current knowledge of marine turtle spatial and foraging ecology as well as threats faced, with particular emphasis on Mediterranean loggerhead and green turtles. By conducting an extensive review in Chapter 2, I demonstrate how SIA has been used to enhance our understanding of marine turtle ecology, as well as help inform conservation initiatives. I also highlight knowledge gaps (for example, bias in the species studied) and provide recommendations for future SIA studies (for example, following standardised protocols), and use this information to inform latter chapters. In Chapter 3, using SIA I highlight the ecological complexity of juvenile Mediterranean loggerhead turtles, demonstrating there are inter- and intra-population variations in ecology, and that region- and habitat-specific fisheries management is required. In Chapter 4, I identify the foraging grounds for two major Mediterranean loggerhead turtle populations, demonstrate foraging site fidelity over decades, show the proportion of females recruiting from each foraging region does not differ across the multi-decadal study, and suggest site-specific management would be beneficial. Finally, in Chapter 5, I show that migratory dive behaviours of loggerhead and green turtles are influenced by changes in environmental conditions (e.g. wave height and temperature) and that the species-specific migratory corridors used may be due to factors such as feeding preference and physiology, rather than species-specific environmental tolerances, suggesting dynamic and species-specific conservation is required. In Chapter 6, I summarise and discuss the findings from this thesis within the wider context. In conclusion, this thesis emphasises the complexities of marine turtle spatial ecology, shows that habitat use will likely differ under future climate scenarios, and suggests targeted and dynamic conservation is required for effective long term conservation.
Abstract.
Collins C, Bech Letessier T, Broderick A, Wijesundara I, Nuno A (2020). Using perceptions to examine human responses to blanket bans: the case of the thresher shark landing-ban in Sri Lanka.
Marine Policy,
121Abstract:
Using perceptions to examine human responses to blanket bans: the case of the thresher shark landing-ban in Sri Lanka
Species-specific bans are increasingly being implemented to stem loss of vulnerable marine species, but there is a paucity of evaluative research into resulting socio-economic and ecological consequences. In 2012, a blanket ban on landing Alopiidae (thresher) sharks was introduced in Sri Lanka. We used fisher perceptions, shown to influence support and compliance with conservation policies, to examine human responses. Data, gathered over a ten-month period in 2019 from focus groups and informal engagement during site visits, suggest support for the ban was lowest amongst fishers who perceived negative social consequences to be higher. Perceptions were also undermined by feelings of poor engagement from institutions and a lack of ecological necessity. The ban appears effective in halting targeted fisheries; however, persistent bycatch was reported by fishers. Further, bycatch appears to be widely unrecorded partly owing to mistrust and confusion amongst fishers. Occasional illegal landings were reported, seemingly motivated by interlinked factors such as good economic returns for thresher meat and high vessel running costs. The potential severity and inequity in social consequences stemming from blanket bans was highlighted, particularly when bycatch and targeted fisheries co-exist. Case study lessons are translated into a checklist containing key questions, designed to aid policy-makers to assess data provision and needs prior to introducing bans. Increasing data provision could enhance the capability of policies to predict and adapt to human behavioural responses, a key requirement considering continuing global declines in sharks despite increasing conservation effort.
Abstract.
2019
Cerritelli G, Bianco G, Santini G, Broderick AC, Godley BJ, Hays GC, Luschi P, Åkesson S (2019). Assessing reliance on vector navigation in the long-distance oceanic migrations of green sea turtles.
Behavioral Ecology,
30(1), 68-79.
Abstract:
Assessing reliance on vector navigation in the long-distance oceanic migrations of green sea turtles
Vector navigation, i.e. maintaining a constant heading for a given amount of time, is hypothesized to provide a viable basis for the navigational feats of a number of long-distance animal migrants. Since animals following this strategy are subject to drift by wind or by ocean current, performing long migrations relying on vector navigation is particularly challenging. We tested whether vector navigation could be involved in the migrations of green turtles (Chelonia mydas) that migrate between the remote Ascension Island and Brazil. To this aim, a novel approach was followed using individual-based numerical models to simulate migratory trajectories of virtual turtles that were compared to actual routes reconstructed by satellite. Simulated postnesting migrations from Ascension revealed that weak currents enabled modeled turtles to reach the Brazilian coast, but only for a limited range of headings around due West. This conclusion was corroborated by comparing modeled trajectories with the actual routes of previously tracked turtles, with a beeline vector navigation strategy providing the best fit, although a true-navigation strategy directed to the landfall site produced similar results. Finally, we tested if a vector navigational strategy was feasible for the prebreeding migration from Brazil towards Ascension, but modeled routes mostly failed to reach the island or a larger area around it, with individuals drifting away under the influence of currents. We conclude that Ascension turtles can take advantage of vector navigation when migrating towards a wide target like the Brazilian coast, while the demanding prebreeding migration likely requires more complex navigational systems.
Abstract.
Patrício AR, Varela MR, Barbosa C, Broderick AC, Catry P, Hawkes LA, Regalla A, Godley BJ (2019). Climate change resilience of a globally important sea turtle nesting population.
Glob Chang Biol,
25(2), 522-535.
Abstract:
Climate change resilience of a globally important sea turtle nesting population.
Few studies have looked into climate change resilience of populations of wild animals. We use a model higher vertebrate, the green sea turtle, as its life history is fundamentally affected by climatic conditions, including temperature-dependent sex determination and obligate use of beaches subject to sea level rise (SLR). We use empirical data from a globally important population in West Africa to assess resistance to climate change within a quantitative framework. We project 200 years of primary sex ratios (1900-2100) and create a digital elevation model of the nesting beach to estimate impacts of projected SLR. Primary sex ratio is currently almost balanced, with 52% of hatchlings produced being female. Under IPCC models, we predict: (a) an increase in the proportion of females by 2100 to 76%-93%, but cooler temperatures, both at the end of the nesting season and in shaded areas, will guarantee male hatchling production; (b) IPCC SLR scenarios will lead to 33.4%-43.0% loss of the current nesting area; (c) climate change will contribute to population growth through population feminization, with 32%-64% more nesting females expected by 2120; (d) as incubation temperatures approach lethal levels, however, the population will cease growing and start to decline. Taken together with other factors (degree of foraging plasticity, rookery size and trajectory, and prevailing threats), this nesting population should resist climate change until 2100, and the availability of spatial and temporal microrefugia indicates potential for resilience to predicted impacts, through the evolution of nest site selection or changes in nesting phenology. This represents the most comprehensive assessment to date of climate change resilience of a marine reptile using the most up-to-date IPCC models, appraising the impacts of temperature and SLR, integrated with additional ecological and demographic parameters. We suggest this as a framework for other populations, species and taxa.
Abstract.
Author URL.
Maxwell SM, Broderick AC, Dutton PH, Fossette-Halot S, Fuentes MMPB, Reina RD (2019). Editorial: Advances in the Biology and Conservation of Marine Turtles.
FRONTIERS IN MARINE SCIENCE,
6 Author URL.
Barbanti A, Turmo M, Blumenthal J, Boyle J, Broderick A, Collyer L, Ebanks-Petrie G, Godley B, Pascual M, Carreras C, et al (2019). Founding in action: genetic assessment of new populations from the same reintroduction program. Frontiers in Marine Science, 6
Haywood J, Fuller W, Godley B, Shutler J, Widdicombe S, Broderick A (2019). Global review and inventory: how stable isotopes are helping us understand ecology and inform conservation of marine turtles. Marine Ecology Progress Series, 613, 217-245.
Barbanti A, Martin C, Blumenthal JM, Boyle J, Broderick AC, Collyer L, Ebanks-Petrie G, Godley BJ, Mustin W, Ordóñez V, et al (2019). How many came home? Evaluating ex situ conservation of green turtles in the Cayman Islands.
Mol Ecol,
28(7), 1637-1651.
Abstract:
How many came home? Evaluating ex situ conservation of green turtles in the Cayman Islands.
Ex situ management is an important conservation tool that allows the preservation of biological diversity outside natural habitats while supporting survival in the wild. Captive breeding followed by re-introduction is a possible approach for endangered species conservation and preservation of genetic variability. The Cayman Turtle Centre Ltd was established in 1968 to market green turtle (Chelonia mydas) meat and other products and replenish wild populations, thought to be locally extirpated, through captive breeding. We evaluated the effects of this re-introduction programmme using molecular markers (13 microsatellites, 800-bp D-loop and simple tandem repeat mitochondrial DNA sequences) from captive breeders (N = 257) and wild nesting females (N = 57) (sampling period: 2013-2015). We divided the captive breeders into three groups: founders (from the original stock), and then two subdivisions of F1 individuals corresponding to two different management strategies, cohort 1995 ("C1995") and multicohort F1 ("MCF1"). Loss of genetic variability and increased relatedness was observed in the captive stock over time. We found no significant differences in diversity among captive and wild groups, and similar or higher levels of haplotype variability when compared to other natural populations. Using parentage and sibship assignment, we determined that 90% of the wild individuals were related to the captive stock. Our results suggest a strong impact of the re-introduction programmme on the present recovery of the wild green turtle population nesting in the Cayman Islands. Moreover, genetic relatedness analyses of captive populations are necessary to improve future management actions to maintain genetic diversity in the long term and avoid inbreeding depression.
Abstract.
Author URL.
Snape R (2019). Investigating conflict between threatened marine megavertebrates and Mediterranean small-scale fisheries.
Abstract:
Investigating conflict between threatened marine megavertebrates and Mediterranean small-scale fisheries
Most fish stocks are being extracted at unsustainable rates and through bycatch, many marine megavertebrate species have unfavourable conservation status. The sheer number and diversity of small-scale fishing vessels worldwide presents a challenge to monitoring and research, therefore compared to industrialised fisheries, little is known about their activities or their sustainability. This thesis addresses this information gap by examining motorised polyvalent vessels
Abstract.
Omeyer L (2019). Investigating life-history traits of adult Mediterranean sea turtles.
Abstract:
Investigating life-history traits of adult Mediterranean sea turtles
The management of species of conservation concern requires high-quality life-history data to model and assess population stocks. This is particularly important for long-lived, migratory species with slow life-histories. In the case of sea turtles, the estimation of demographic parameters is a priority for the species globally and, in particular, in the Mediterranean Sea. In this thesis, I focus on green (Chelonia mydas) and loggerhead (Caretta caretta) turtles which nest sympatrically at Alagadi Beach, North Cyprus, where intensive monitoring and saturation tagging have been undertaken since 1993. This thesis aims to make use of this 26-year individual-based dataset both to further and to challenge current knowledge and theories surrounding life-history traits. More specifically, in Chapter 2, I review the state of knowledge of the growth strategy of adult sea turtles and life-history trade-offs. I highlight that, although studies of turtles in captivity have provided insights into changes in energy allocation at sexual maturity, there is a lack of data regarding the temporal variation in post-maturity growth rates in wild individuals. Thus, in Chapter 3, I provide evidence suggesting that, contrary to previous thinking, green and loggerhead turtles do not grow throughout their life. This clearly has implications for our understanding of ageing and longevity of the species. Additionally, in Chapter 4, I offer the first study of the effects of biologging device attachment on growth, reproduction and survival of nesting females. While the absence of an effect at this study site is promising considering how widely this technique is used in sea turtles, I stress the need for similar studies elsewhere to confirm this finding. Furthermore, I examine in Chapter 5 the importance of passive integrated transponder (PIT) tags and show that they greatly improve estimates of flipper tag loss and life-history and demographic parameters, essential for population assessments. Lastly, I use results from previous chapters in Chapter 6 to investigate the difference in recovery rates of the two species. I propose that high bycatch rates in the Mediterranean Sea are hampering the recovery of loggerhead turtles at this study site, whereas green turtles are showing signs of exponential recovery. In conclusion, this thesis emphasises the importance of long-term studies to refine life-history models and provides new and improved data for Mediterranean sea turtles, which can be used in regional and global IUCN Red List assessments.
Abstract.
Duncan EM, Broderick AC, Fuller WJ, Galloway TS, Godfrey MH, Hamann M, Limpus CJ, Lindeque PK, Mayes AG, Omeyer LCM, et al (2019). Microplastic ingestion ubiquitous in marine turtles.
Glob Chang Biol,
25(2), 744-752.
Abstract:
Microplastic ingestion ubiquitous in marine turtles.
Despite concerns regarding the environmental impacts of microplastics, knowledge of the incidence and levels of synthetic particles in large marine vertebrates is lacking. Here, we utilize an optimized enzymatic digestion methodology, previously developed for zooplankton, to explore whether synthetic particles could be isolated from marine turtle ingesta. We report the presence of synthetic particles in every turtle subjected to investigation (n = 102) which included individuals from all seven species of marine turtle, sampled from three ocean basins (Atlantic [ATL]: n = 30, four species; Mediterranean (MED): n = 56, two species; Pacific (PAC): n = 16, five species). Most particles (n = 811) were fibres (ATL: 77.1% MED: 85.3% PAC: 64.8%) with blue and black being the dominant colours. In lesser quantities were fragments (ATL: 22.9%: MED: 14.7% PAC: 20.2%) and microbeads (4.8%; PAC only; to our knowledge the first isolation of microbeads from marine megavertebrates). Fourier transform infrared spectroscopy (FT-IR) of a subsample of particles (n = 169) showed a range of synthetic materials such as elastomers (MED: 61.2%; PAC: 3.4%), thermoplastics (ATL: 36.8%: MED: 20.7% PAC: 27.7%) and synthetic regenerated cellulosic fibres (SRCF; ATL: 63.2%: MED: 5.8% PAC: 68.9%). Synthetic particles being isolated from species occupying different trophic levels suggest the possibility of multiple ingestion pathways. These include exposure from polluted seawater and sediments and/or additional trophic transfer from contaminated prey/forage items. We assess the likelihood that microplastic ingestion presents a significant conservation problem at current levels compared to other anthropogenic threats.
Abstract.
Author URL.
Tilley D, Ball S, Ellick J, Godley BJ, Weber N, Weber SB, Broderick AC (2019). No evidence of fine scale thermal adaptation in green turtles.
Journal of Experimental Marine Biology and Ecology,
514-515, 110-117.
Abstract:
No evidence of fine scale thermal adaptation in green turtles
Adaptation to increasing temperatures may enable species to mitigate the long-term impacts of climate change. Sea turtles have temperature dependent sex determination (TSD) and variation in the thermal reaction norm, which influences offspring sex ratio, has been suggested as a potential adaptive mechanism to rising global temperatures. Here, we investigate the sex ratio of green turtle Chelonia mydas offspring from nests on beaches with notable differences in their thermal properties, to look for evidence of localised adaptation. We compared pivotal temperatures and hatch success in both the laboratory and in situ using eggs laid on two nesting beaches (dark vs. pale sand) at Ascension Island that represent the extremes of the range of incubation temperatures experienced by this population. We found no effect of beach of origin on pivotal temperatures, hatch success, or hatchling size in the laboratory or the wild. This suggests that turtles from the same rookery are not locally adapted to different thermal conditions experienced during incubation. Under predicted climate change scenarios, this will result in reduced hatch success and an increased proportion of female offspring unless temporal or spatial range shifts occur.
Abstract.
Duncan E (2019). The Impact of Plastic Pollution on Marine Turtles.
Abstract:
The Impact of Plastic Pollution on Marine Turtles
Plastic debris is entering into the marine environment at an accelerating rate, now becoming one of the most ubiquitous and long-lasting changes in natural systems. Marine turtles are large marine vertebrates with complex life histories and highly mobile behaviour that may make them particularly vulnerable to its impacts. The main goals of this thesis were to i) evaluate the potential implications of the presence of plastic pollution in the environment to marine turtles by reviewing current literature ii) provide a global summary of the issue of entanglement in this taxon, utilising a global network of experts iii) explore the drivers of key interactions between marine turtles and plastic ingestion and develop novel additions classification methodologies to explore selective ingestion of plastics iv) develop a methodology for investigating and isolating the presence of microplastic ingestion in marine turtle gut content and v) examine plastic pollution on a key habitat for marine turtles e.g. nesting beaches. Major findings of the thesis include i) the issue of entanglement with plastic debris, the majority in ghost fishing gear, is both an under-reported and under-researched threat ii) a clear display of strong diet-related ingestion towards plastic debris that resemble natural food items, utilising a case study of green turtles in Northern Cyprus iii) a method development that allowed the identification and isolation of a suite synthetic particles in gut content residue samples, providing evidence of ingestion of synthetic debris at the microscopic size class iv) a more comprehensive viewpoint on plastic concentrations on nesting beaches, in the form of 3D sampling to investigate subsurface plastic densities, showing microplastics present down to turtle nesting depth of both loggerhead and green turtles in Northern Cyprus. In conclusion, this thesis forms the most detailed and comprehensive investigation to date on the impacts of this pollutant on the taxon of marine turtles; contributing to knowledge into macro and microplastic ingestion, entanglement and key habitats through method development and integration of marine turtle feeding ecology and developmental biology.
Abstract.
Omeyer LCM, Broderick AC, Godley BJ, Snape RTE, Fuller WJ (2019). The effect of biologging systems on reproduction, growth and survival of adult sea turtles.
Movement Ecology,
7(2), 1-12.
Abstract:
The effect of biologging systems on reproduction, growth and survival of adult sea turtles
Background:. Telemetry and biologging systems, ‘tracking’ hereafter, have been instrumental in meeting the challenges associated with studying the ecology and behaviour of cryptic, wide-ranging marine mega-vertebrates. Over recent decades, globally, sea turtle tracking has increased exponentially, across species and life-stages, despite a paucity of studies investigating the effects of such devices on study animals. Indeed, such studies are key to informing whether data collected are unbiased and, whether derived estimates can be considered typical of the population at large.
Methods:. Here, using a 26-year individual-based monitoring dataset on sympatric green (Chelonia mydas) and loggerhead (Caretta caretta) turtles, we provide the first analysis of the effects of device attachment on reproduction, growth and survival of nesting females.
Results:. We found no significant difference in growth and reproductive correlates between tracked and non-tracked females in the years following device attachment. Similarly, when comparing pre- and post-tracking data, we found no significant difference in the reproductive correlates of tracked females for either species or significant carry-over effects of device attachment on reproductive correlates in green turtles. The latter was not investigated for loggerhead turtles due to small sample size. Finally, we found no significant effects of device attachment on return rates or survival of tracked females for either species.
Conclusion:. While there were no significant detrimental effects of device attachment on adult sea turtles in this region, our study highlights the need for other similar studies elsewhere and the value of long-term individual-based monitoring.
Abstract.
Tilley D (2019). The green sea turtle: adaptation and resilience to climate change.
Abstract:
The green sea turtle: adaptation and resilience to climate change
Sea turtles are a globally distributed migratory species that use a range of habitats during their life cycle, including both land and sea. As egg laying ectotherms they are particularly susceptible to variation in temperature, especially during clutch incubation. Climate change models predict increasing temperatures over the course of the century, along with sea level rise, and changes in weather patterns. Understanding how these factors impact the environment and such ectothermic species is key to their survival. The green sea turtle, Chelonia mydas, is one of the best studied sea turtle species, and like all seven species they are of conservation concern, thus understanding the impact of climate change on this group is of importance for their conservation. In this thesis I seek to investigate the impacts of temperature on offspring sex ratios and hatching success, two key parameters in the reproductive biology of sea turtles, using the Ascension Island rookery as model population. This will infer knowledge on adaptation and resilience to climate change.
I first carry out a literature review (Chapter 2) to evaluate the existing knowledge of current primary sex ratios, and find that despite nearly four decades of work on the topic, little progress has been made. Indeed, only four studies have been published on sex determining temperatures in laboratory conditions, and a range of varying methods have been used. I then carried out a laboratory-based study to establish the pivotal temperature, the temperature at which an equal proportion of male and females are produced, (29.3°C) for the Ascension Island green turtle rookery (Chapter 3) and carry out a translocation experiment to determine whether maternal philopatry confers any form of advantage to incubating clutches through localised adaptation (Chapter 4). Neither under laboratory conditions, nor in-situ do I find any evidence of localised thermal adaptation; hatching success drops with increasing temperatures, and clutches from different thermal backgrounds produce equivalent proportions of males and females. Finally, I use this information to evaluate island wide sex ratios and offspring output, based on different climate projection scenarios (Chapter 5). I find that the primary sex ratio will likely be extremely female biased (> 90%) by the end of the century, with hatching success starting to decrease in the most extreme scenarios, especially at the darker beaches where temperatures will exceed thresholds for successful incubation. The geographic isolation of Ascension Island means that there are limited opportunities for dispersal. A full assessment of the impacts of climate change on sea level rise, coastal erosion and changes in weather patterns may provide more information on the treats and opportunities that this population faces. In the meantime, a change in nesting seasonality or nesting distribution within the beaches of Ascension may provide critical to mitigate the impacts of increasing temperatures.
Abstract.
Omeyer LCM, Casale P, Fuller WJ, Godley BJ, Holmes KE, Snape RTE, Broderick AC (2019). The importance of passive integrated transponder (PIT) tags for measuring life-history traits of sea turtles.
Biological Conservation,
240Abstract:
The importance of passive integrated transponder (PIT) tags for measuring life-history traits of sea turtles
© 2019 the Authors Capture-mark-recapture studies rely on the identification of individuals through time, using markers or tags, which are assumed to be retained. This assumption, however, may be violated, having implications for population models. In sea turtles, individual identification is typically based on external flipper tags, which can be combined with internal passive integrated transponder (PIT) tags. Despite the extensive use of flipper tags, few studies have modelled tag loss using continuous functions. Using a 26-year dataset for sympatrically nesting green (Chelonia mydas) and loggerhead (Caretta caretta) turtles, this study aims to assess how PIT tag use increases the accuracy of estimates of life-history traits. The addition of PIT tags improved female identification: between 2000 and 2017, 53% of green turtles and 29% of loggerhead turtles were identified from PIT tags alone. We found flipper and PIT tag losses were best described by decreasing logistic curves with lower asymptotes. Excluding PIT tags from our dataset led to underestimation of flipper tag loss, reproductive periodicity, reproductive longevity and annual survival, and overestimation of female abundance and recruitment for both species. This shows the importance of PIT tags in improving the accuracy of estimates of life-history traits. Thus, estimates where tag loss has not been corrected for should be interpreted with caution and could bias IUCN Red List assessments. As such, long-term population monitoring programmes should aim to estimate tag loss and assess the impact of loss on life-history estimates, to provide robust estimates without which population models and stock assessments cannot be derived accurately.
Abstract.
Colman LP, Thomé JCA, Almeida ADP, Baptistotte C, Paulo PC, Broderick AC, Ribeiro FA, Vila-Verde L, Godley BJ (2019). Thirty years of leatherback turtle Dermochelys coriacea nesting in Espírito Santo, Brazil, 1988-2017: Reproductive biology and conservation.
Endangered Species Research,
39, 147-158.
Abstract:
Thirty years of leatherback turtle Dermochelys coriacea nesting in Espírito Santo, Brazil, 1988-2017: Reproductive biology and conservation
In the southwestern Atlantic Ocean, leatherback turtles Dermochelys coriacea are only known to regularly nest in eastern Brazil, on the coast of the state of Espírito Santo. Here, we present an analysis of the nesting ecology, population trends and conservation status of this leather - back turtle colony between 1988 and 2017. We observed an increasing, although variable, trend in the annual number of nests, with the mean increasing from 25.6 nests in the first 5 yr of the study to 89.8 in the last 5 yr. Concurrently, there was also a significant decrease in the mean curved carapace length of the population, which we hypothesize was caused by recruitment of new females to the nesting population. Throughout the study period, nests were concentrated in the southern part of the 160 km long study area. No change was observed in the annual median nesting date. Mean annual hatching success was 66.0% and no significant variation in hatching success was detected after a major spill of mining tailings into the nesting area in 2015. We postulate that local conservation actions that started in the 1980s have contributed to the gentle recovery of this population; however, given the small population size and restricted nesting geographical distribution alongside the persistence of various threats-fisheries bycatch, climate change, pollution and coastal development-this population continues to be of conservation concern.
Abstract.
2018
Snape RTE, Broderick AC, Çiçek BA, Fuller WJ, Tregenza N, Witt MJ, Godley BJ (2018). Conflict between Dolphins and a Data-Scarce Fishery of the European Union.
Human Ecology,
46(3), 423-433.
Abstract:
Conflict between Dolphins and a Data-Scarce Fishery of the European Union
Fisheries depredation by marine mammals is an economic concern worldwide. We combined questionnaires, acoustic monitoring, and participatory experiments to investigate the occurrence of bottlenose dolphins in the fisheries of Northern Cyprus, and the extent of their conflict with set-nets, an economically important metier of Mediterranean fisheries. Dolphins were present in fishing grounds throughout the year and were detected at 28% of sets. Net damage was on average six times greater where dolphins were present, was correlated with dolphin presence, and the associated costs were considerable. An acoustic deterrent pinger was tested, but had no significant effect although more powerful pingers could have greater impact. However, our findings indicate that effective management of fish stocks is urgently required to address the overexploitation that is likely driving depredation behaviour in dolphins, that in turn leads to net damage and the associated costs to the fisheries.
Abstract.
Bradshaw PJ, Broderick AC, Carreras C, Fuller W, Snape RTE, Wright LI, Godley BJ (2018). Defining conservation units with enhanced molecular tools to reveal fine scale structuring among Mediterranean green turtle rookeries.
Biological Conservation,
222, 253-260.
Abstract:
Defining conservation units with enhanced molecular tools to reveal fine scale structuring among Mediterranean green turtle rookeries
Understanding the connectivity among populations is a key research priority for species of conservation concern. Genetic tools are widely used for this purpose, but the results can be limited by the resolution of the genetic markers in relation to the species and geographic scale. Here, we investigated natal philopatry in green turtles (Chelonia mydas) from four rookeries within close geographic proximity (~200 km) on the Mediterranean island of Cyprus. We genotyped hypervariable mtSTRs, a mtDNA control region sequence (CR) and 13 microsatellite loci to genetically characterise 479 green turtles using markers with different modes of inheritance. We demonstrated matrilineal stock structure for the first time among Mediterranean green turtle rookeries. This result contradicts previous regional assessments and supports a growing body of evidence that green turtles exhibit a more precise level of natal site fidelity than has commonly been recognised. The microsatellites detected weak male philopatry with significant stock structure among three of the six pairwise comparisons. The absence of Atlantic CR haplotypes and mtSTRs amongst these robust sample sizes reaffirms the reproductive isolation of Mediterranean green turtles and supports their status as a subpopulation. A power analysis effectively demonstrated that the mtDNA genetic markers previously employed to evaluate regional stock identity were confounded by an insufficient resolution considering the recent colonisation of this region. These findings improve the regional understanding of stock connectivity and illustrate the importance of using suitable genetic markers to define appropriate units for management and conservation.
Abstract.
Omeyer LCM, Fuller WJ, Godley BJ, Snape RTE, Broderick AC (2018). Determinate or indeterminate growth? Revisiting the growth strategy of sea turtles.
Marine Ecology Progress Series,
596, 199-211.
Abstract:
Determinate or indeterminate growth? Revisiting the growth strategy of sea turtles
Traditionally, growth can be either determinate, ceasing during the natural lifespan of individuals, or indeterminate, persisting throughout life. Although indeterminate growth is a widely accepted strategy and believed to be ubiquitous among long-lived species, it may not be as common as previously thought. Sea turtles are believed to be indeterminate growers despite the paucity of long-term studies into post-maturity growth. In this study, we provide the first temporal analysis of post-maturity growth rates in wild living sea turtles, using 26 yr of data on individual measurements of females nesting in Cyprus. We used generalised additive/linear mixed models to incorporate multiple growth measurements for each female and model post-maturity growth over time. We found post-maturity growth to persist in green Chelonia mydas and loggerhead Caretta caretta turtles, with growth decreasing for approximately 14 yr before plateauing around zero for a further decade solely in green turtles. We also found growth to be independent of size at sexual maturity in both species. Additionally, although annual growth and compound annual growth rates were higher in green turtles than in loggerhead turtles, this difference was not statistically significant. While indeterminate growth is believed to be a key life-history trait of ectothermic vertebrates, here, we provide evidence of determinate growth in green and loggerhead turtles and suggest that determinate growth is a life-history trait shared by cheloniid species. Our results highlight the need for long-term studies to refine life-history models and further our understanding of ageing and longevity of wild sea turtles for conservation and management.
Abstract.
Poggio Colman L (2018). Ecology and conservation of the leatherback sea turtle (Dermochelys coriacea) nesting in Brazil.
Abstract:
Ecology and conservation of the leatherback sea turtle (Dermochelys coriacea) nesting in Brazil
Knowledge of life-history parameters of marine turtles is essential for understanding their ecology and for effective conservation. The leatherback turtle (Dermochelys coriacea) is globally classified as Vulnerable by the International Union of Conservation of Nature (IUCN), however, distinct subpopulations are recognised and require specific data for the assessment of their conservation status. The Southwest Atlantic Ocean subpopulation is known to regularly nest only in eastern Brazil, on the coast of the state of Espírito Santo. This thesis presents a collection of chapters that investigate the ecology and conservation of this taxon. Multiple technologies and methodologies are employed to ask both ecological and management questions, assessing key population parameters to inform conservation. Here I use long-term data (30 years) to investigate the nesting ecology, population trends and conservation status of leatherback turtles in Espírito Santo. I explore their nesting environment and provide baseline data which will guide further research and management strategies under future scenarios of climate change. I investigate the marine habitat use through stable isotope approaches and satellite telemetry to infer spatial ecology, setting out the conservation situation and perspectives of this important population. Finally, I assess the potential impacts of artificial light on wildlife, using marine turtles in Brazil as a case study. The leatherback turtle rookery in Espírito Santo shows signs of population recovery, however, the existence of various threats means this population remains subject of conservation concern.
Abstract.
Casale P, Broderick AC, Camiñas JA, Cardona L, Carreras C, Demetropoulos A, Fuller WJ, Godley BJ, Hochscheid S, Kaska Y, et al (2018). Mediterranean sea turtles: Current knowledge and priorities for conservation and research.
Endangered Species Research,
36, 229-267.
Abstract:
Mediterranean sea turtles: Current knowledge and priorities for conservation and research
© the authors 2018. The available information regarding the 2 sea turtle species breeding in the Mediterranean (loggerhead turtle Caretta caretta and green turtle Chelonia mydas) is reviewed, including biometrics and morphology, identification of breeding and foraging areas, ecology and behaviour, abundance and trends, population structure and dynamics, anthropogenic threats and conservation measures. Although a large body of knowledge has been generated, research efforts have been inconsistently allocated across geographic areas, species and topics. Significant gaps still exist, ranging from the most fundamental aspects, such as the distribution of major nesting sites and the total number of clutches laid annually in the region, to more specific topics like age at maturity, survival rates and behavioural ecology, especially for certain areas (e.g. south-eastern Mediterranean). These gaps are particularly marked for the green turtle. The recent positive trends of nest counts at some nesting sites may be the result of the cessation of past exploitation and decades of conservation measures on land, both in the form of national regulations and of continued active protection of clutches. Therefore, the current status should be considered as dependent on such ongoing conservation efforts. Mitigation of incidental catch in fisheries, the main anthropogenic threat at sea, is still in its infancy. From the analysis of the present status a comprehensive list of re search and conservation priorities is proposed.
Abstract.
Tikochinski Y, Bradshaw P, Mastrogiacomo A, Broderick A, Daya A, Demetropoulos A, Demetropoulos S, Eliades NG, Fuller W, Godley B, et al (2018). Mitochondrial DNA short tandem repeats unveil hidden population structuring and migration routes of an endangered marine turtle.
Aquatic Conservation: Marine and Freshwater Ecosystems,
28(4), 788-797.
Abstract:
Mitochondrial DNA short tandem repeats unveil hidden population structuring and migration routes of an endangered marine turtle
The assessment of the composition and dynamics of endangered populations is crucial for management and conservation, and appropriate genetic markers are critical. The genetic structuring of the Mediterranean green turtle (Chelonia mydas) populations and the origin of the stranded animals found along the Israeli coast was investigated using new highly polymorphic short tandem repeat (STR) markers. The structuring of nesting populations was studied using pairwise genetic distances and a principal coordinates analysis (PCoA). The contribution of the different nesting populations to the stranded sample was assessed by using a mixed-stock analysis. A clear population genetic structure, not detected before, has been revealed. The four nesting populations are genetically well differentiated, and thus should be considered as different management units. The populations from Turkey and Israel showed higher resemblance, despite residing at opposite ends of the Mediterranean distribution. The Turkish nesting population is the main source of the stranded turtles sampled along the Israeli shore, confirming that individuals from this population migrate from north to south along the eastern shore of the Mediterranean, as previously shown by telemetry studies. The use of a highly polymorphic haplotyping method enabled the detection of a clear genetic structuring of the green turtle populations in the eastern Mediterranean Sea that was not revealed in previous studies, demonstrating the importance of marker selection in population genetics. The analysis of the genetic composition of the stranded turtles allowed us to investigate the migration patterns from nesting to foraging areas, supporting previous satellite-tracking and stable-isotope results. These results will help to delineate conservation management units for the species in the Mediterranean, and reveal connectivity among beaches and mixed aggregations.
Abstract.
Patrício AR, Varela MR, Barbosa C, Broderick AC, Ferreira Airaud MB, Godley BJ, Regalla A, Tilley D, Catry P (2018). Nest site selection repeatability of green turtles, Chelonia mydas, and consequences for offspring.
Animal Behaviour,
139, 91-102.
Abstract:
Nest site selection repeatability of green turtles, Chelonia mydas, and consequences for offspring
Nest site selection is a critical behaviour, particularly in species with no parental care, as it can greatly impact offspring survival. Marine turtles depend on sandy beaches to nest, where they select from a range of microhabitats that may differently affect hatchling survival and phenotype. Here we describe the degree of nest site selection at one of the largest green turtle rookeries globally, in Guinea-Bissau, West Africa, and how this impacts offspring. In 2013 and 2014 we recorded the spatial distribution of 1559 nests, and monitored 657 females during oviposition, to assess population and individual preferences on nesting site. Overall, females tended to nest close to the vegetation, at a preferred elevation of 4.8–5.0 m, which was above the highest spring tide (4.7 m), enhancing clutch survival. Individuals displayed high repeatability in nesting microhabitat type (open sand, forest border and forest), distance along the beach, distance to the vegetation and elevation, which may result from this behaviour having a genetic basis or from fine-scale nest site philopatry. Hatchlings from cooler nests were larger, potentially dispersing faster and more able to evade predators, while smaller hatchlings, from warmer nests, retained more energetic reserves (residual yolk), which may also be advantageous for initial dispersal, particularly if food is scarce. Thus, individual preferences in nest site selection led to trade-offs in offspring phenotype, but overall, most nesting females selected sites that increased offspring survival, suggesting that nest site selection is an adaptive trait that has been under selection. As under future climate change scenarios females nesting in upper shaded areas should have higher fitness, individual consistency in nesting microhabitat provides opportunity for natural selection to occur.
Abstract.
Snape RTE, Bradshaw PJ, Broderick AC, Fuller WJ, Stokes KL, Godley BJ (2018). Off-the-shelf GPS technology to inform marine protected areas for marine turtles.
Biological Conservation,
227, 301-309.
Abstract:
Off-the-shelf GPS technology to inform marine protected areas for marine turtles
The financial expense of tracking solutions often impedes effective characterisation of habitat use in threatened marine megavertebrates. Yet some of these taxa predictably aggregate at coastal breeding sites, providing conservation opportunities. Toward a low-cost solution for tracking marine megavertebrates, we trial conventional GPS data loggers against Argos satellite transmitters for assessing inter-nesting habitat use of marine turtles. Devices were attached to green (Chelonia mydas) and loggerhead (Caretta caretta) turtles nesting at a study site in Cyprus, where patrol teams were in place to retrieve GPS loggers from turtles returning to lay subsequent clutches. GPS tracking revealed loggerhead turtles to predominantly use areas outside the boundaries of an MPA proposed for the region, while both species under-used much of the MPA area. Due to high location error, Argos data were considered unsuitable for such fine-scale assessments (all location classes except Z were included in our analysis). However, Argos tracking showed half the loggerhead turtles sampled also nested outside of the patrolled study area, demonstrating connectivity with other proposed MPAs. This was not accounted for by GPS tracking, because females exhibiting this behaviour rarely returned to the study beach, precluding GPS retrieval, thus, demonstrating the power of remote data access. The low-cost GPS technology could be considered in similar cases, where recapture is likely and where funding barriers preclude the use of Argos-relay fast-acquisition GPS technology. In combining the accuracy GPS and the continuity of Argos, the latter provides the best solution in most scenarios, but at far greater cost.
Abstract.
Oppel S, Bolton M, Carneiro APB, Dias MP, Green JA, Masello JF, Phillips RA, Owen E, Quillfeldt P, Beard A, et al (2018). Spatial scales of marine conservation management for breeding seabirds.
Marine Policy,
98, 37-46.
Abstract:
Spatial scales of marine conservation management for breeding seabirds
Knowing the spatial scales at which effective management can be implemented is fundamental for conservation planning. This is especially important for mobile species, which can be exposed to threats across large areas, but the space use requirements of different species can vary to an extent that might render some management approaches inefficient. Here the space use patterns of seabirds were examined to provide guidance on whether conservation management approaches should be tailored for taxonomic groups with different movement characteristics. Seabird tracking data were synthesised from 5419 adult breeding individuals of 52 species in ten families that were collected in the Atlantic Ocean basin between 1998 and 2017. Two key aspects of spatial distribution were quantified, namely how far seabirds ranged from their colony, and to what extent individuals from the same colony used the same areas at sea. There was evidence for substantial differences in patterns of space-use among the ten studied seabird families, indicating that several alternative conservation management approaches are needed. Several species exhibited large foraging ranges and little aggregation at sea, indicating that area-based conservation solutions would have to be extremely large to adequately protect such species. The results highlight that short-ranging and aggregating species such as cormorants, auks, some penguins, and gulls would benefit from conservation approaches at relatively small spatial scales during their breeding season. However, improved regulation of fisheries, bycatch, pollution and other threats over large spatial scales will be needed for wide-ranging and dispersed species such as albatrosses, petrels, storm petrels and frigatebirds.
Abstract.
Rees AF, Avens L, Ballorain K, Bevan E, Broderick AC, Carthy RR, Christianen MJA, Duclos G, Heithaus MR, Johnston DW, et al (2018). The potential of unmanned aerial systems for sea turtle research and conservation: a review and future directions.
Endangered Species Research,
35, 81-100.
Abstract:
The potential of unmanned aerial systems for sea turtle research and conservation: a review and future directions
© the authors 2018. The use of satellite systems and manned aircraft surveys for remote data collection has been shown to be transformative for sea turtle conservation and research by enabling the collection of data on turtles and their habitats over larger areas than can be achieved by surveys on foot or by boat. Unmanned aerial vehicles (UAVs) or drones are increasingly being adopted to gather data, at previously unprecedented spatial and temporal resolutions in diverse geographic locations. This easily accessible, low-cost tool is improving existing research methods and enabling novel approaches in marine turtle ecology and conservation. Here we review the diverse ways in which incorporating inexpensive UAVs may reduce costs and field time while improving safety and data quality and quantity over existing methods for studies on turtle nesting, at-sea distribution and behaviour surveys, as well as expanding into new avenues such as surveillance against illegal take. Furthermore, we highlight the impact that high-quality aerial imagery captured by UAVs can have for public outreach and engagement. This technology does not come without challenges. We discuss the potential constraints of these systems within the ethical and legal frameworks which researchers must operate and the difficulties that can result with regard to storage and analysis of large amounts of imagery. We then suggest areas where technological development could further expand the utility of UAVs as data-gathering tools; for example, functioning as downloading nodes for data collected by sensors placed on turtles. Development of methods for the use of UAVs in sea turtle research will serve as case studies for use with other marine and terrestrial taxa.
Abstract.
Duncan EM, Arrowsmith J, Bain C, Broderick AC, Lee J, Metcalfe K, Pikesley SK, Snape RTE, van Sebille E, Godley BJ, et al (2018). The true depth of the Mediterranean plastic problem: Extreme microplastic pollution on marine turtle nesting beaches in Cyprus.
Marine Pollution Bulletin,
136, 334-340.
Abstract:
The true depth of the Mediterranean plastic problem: Extreme microplastic pollution on marine turtle nesting beaches in Cyprus
We sampled 17 nesting sites for loggerhead (Caretta caretta) and green turtles (Chelonia mydas) in Cyprus. Microplastics (
Abstract.
Nuno A, Blumenthal JM, Austin TJ, Bothwell J, Ebanks-Petrie G, Godley BJ, Broderick AC (2018). Understanding implications of consumer behavior for wildlife farming and sustainable wildlife trade.
Conserv Biol,
32(2), 390-400.
Abstract:
Understanding implications of consumer behavior for wildlife farming and sustainable wildlife trade.
Unsustainable wildlife trade affects biodiversity and the livelihoods of communities dependent upon those resources. Wildlife farming has been proposed to promote sustainable trade, but characterizing markets and understanding consumer behavior remain neglected but essential steps in the design and evaluation of such operations. We used sea turtle trade in the Cayman Islands, where turtles have been farm raised for human consumption for almost 50 years, as a case study to explore consumer preferences toward wild-sourced (illegal) and farmed (legal) products and potential conservation implications. Combining methods innovatively (including indirect questioning and choice experiments), we conducted a nationwide trade assessment through in-person interviews from September to December 2014. Households were randomly selected using disproportionate stratified sampling, and responses were weighted based on district population size. We approached 597 individuals, of which 37 (6.2%) refused to participate. Although 30% of households had consumed turtle in the previous 12 months, the purchase and consumption of wild products was rare (e.g. 64-742 resident households consumed wild turtle meat [i.e. 0.3-3.5% of households] but represented a large threat to wild turtles in the area due to their reduced populations). Differences among groups of consumers were marked, as identified through choice experiments, and price and source of product played important roles in their decisions. Despite the long-term practice of farming turtles, 13.5% of consumers showed a strong preference for wild products, which demonstrates the limitations of wildlife farming as a single tool for sustainable wildlife trade. By using a combination of indirect questioning, choice experiments, and sales data to investigate demand for wildlife products, we obtained insights about consumer behavior that can be used to develop conservation-demand-focused initiatives. Lack of data from long-term social-ecological assessments hinders the evaluation of and learning from wildlife farming. This information is key to understanding under which conditions different interventions (e.g. bans, wildlife farming, social marketing) are likely to succeed.
Abstract.
Author URL.
2017
Duncan EM, Botterell ZLR, Broderick AC, Galloway TS, Lindeque PK, Nuno A, Godley BJ (2017). A global review of marine turtle entanglement in anthropogenic debris: a baseline for further action.
ENDANGERED SPECIES RESEARCH,
34, 431-448.
Author URL.
Weber SB, Weber N, Godley BJ, Pelembe T, Stroud S, Williams N, Broderick AC (2017). Ascension Island as a mid-Atlantic developmental habitat for juvenile hawksbill turtles.
Journal of the Marine Biological Association of the United Kingdom,
97(4), 813-820.
Abstract:
Ascension Island as a mid-Atlantic developmental habitat for juvenile hawksbill turtles
Ascension Island in the South Atlantic Ocean is renowned for its globally-important nesting population of green turtles (Chelonia mydas) that has been the subject of long-term research. By comparison, very little is known about the apparently small population of hawksbill turtles (Eretmochelys imbricata) that have been recorded in its waters, thousands of kilometres from known nesting beaches. Here, we collate 10 years of in-water tagging data, opportunistic public sighting records and underwater observations to provide a baseline for future research, and present preliminary data on habitat use derived from two individuals fitted with GPS transmitters. Although public sightings were inevitably biased towards popular recreation areas, the resulting distribution suggests that hawksbill turtles occur year round in Ascension Island's waters along the entire 65 km of coastline. Hawksbills were observed feeding on benthic algae and encrusting sponges, and were frequently seen scavenging on fish discards around the Island's pier at night aided by anthropogenic lighting. Between 2003 and 2013, 35 turtles were captured, measured, tagged and then released. Curved carapace lengths ranged from 33.5 to 85 cm (mean = 48.8 cm) indicating that most (if not all) individuals encountered around Ascension are post-pelagic juveniles. Four individuals were recaptured at least once giving a mean minimum residence time of 4.2 yr (range: 2.8-7.3 yr) and a mean growth rate of 2.8 cm yr-1. Turtles fitted with Fastloc™ GPS devices remained at Ascension Island for the duration of the study (>90 days) and occupied restricted home ranges with an average area of 2.5 km2 and an average 'core use area' (50% utilization distribution) of 0.05 km2. Together, these results suggest that Ascension Island serves as a mid-Atlantic developmental habitat for benthic-feeding, juvenile hawksbill turtles on extended oceanic migrations before recruiting to their adult foraging grounds, likely to be located in Brazil or tropical West Africa.
Abstract.
Humber F, Andriamahaino ET, Beriziny T, Botosoamananto R, Godley BJ, Gough C, Pedron S, Ramahery V, Broderick AC (2017). Assessing the small-scale shark fishery of Madagascar through community-based monitoring and knowledge.
Fisheries Research,
186, 131-143.
Abstract:
Assessing the small-scale shark fishery of Madagascar through community-based monitoring and knowledge
Over 90% of those employed in commercial capture fisheries work in the small-scale fisheries (SSF) sector and an estimated 97% of small scale fishers are found in least developed countries. However, the capacity for monitoring SSF globally is low and there is a paucity of data, in particular for remote areas within developing nations. The methods presented here demonstrate a low cost participatory approach for gathering data on small-scale fisheries, in particular for those that take place across remote areas. Community-based data collectors were trained to record biological and socioeconomic data on the traditional (non-motorised) shark fishery in the Toliara region of Madagascar over a six year period (2007–2012). An estimated 20 species of shark were recorded, of which 31% (n = 3505) were Sphyrna lewini (scalloped hammerhead), a species listed by the IUCN as Endangered (IUCN, 2016). Although the number of sharks landed annually has not decreased during our survey period, there was a significant decrease in the average size of sharks caught. Despite multiple anecdotal reports of shark population declines, interviews and focus groups highlight the possibility that shark landings appear to have been maintained through changes in gear and increases in effort (eg. number of fishers, time spent fishing), which may mask a decline in shark populations. The numbers of sharks taken by the traditional fishery in our study region was estimated to be between 65,000 and 104,000 year−1, whilst estimates using national export and import of dried shark fin from Madagascar, and shark length data in this study, put total landings between 78,000 and 471,851 year−1. Reliable data on the total volume of sharks landed in Madagascar's waters is scarce, in particular from foreign industrial boats both directly targeting shark species and as bycatch in fisheries targeting other species. There is currently no legislation in place to protect sharks from overexploitation in Madagascar and an urgent need to address the lack of shark fishery management across the traditional, artisanal and industrial fisheries.
Abstract.
Patrício AR, Marques A, Barbosa C, Broderick AC, Godley BJ, Hawkes LA, Rebelo R, Regalla A, Catry P (2017). Balanced primary sex ratios and resilience to climate change in a major sea turtle population.
Marine Ecology Progress Series,
577, 189-203.
Abstract:
Balanced primary sex ratios and resilience to climate change in a major sea turtle population
Global climate change is expected to have major impacts on biodiversity. Sea turtles have temperature-dependent sex determination, and many populations produce highly femalebiased offspring sex ratios, a skew likely to increase further with global warming. We estimated the primary sex ratio at one of the world's largest green turtle Chelonia mydas rookeries in Guinea-Bissau, West Africa, and explored its resilience to climate change. In 2013 and 2014, we deployed data loggers recording nest (n = 101) and sand (n = 30) temperatures, and identified hatchling sex by histological examination of gonads. A logistic curve was fitted to the data to allow predictions of sex ratio across habitats and through the nesting season. The population-specific pivotal temperature was 29.4°C, with both sexes produced within incubation temperatures from 27.6 to 31.4°C: the transitional range of temperatures (TRT). Primary sex ratio changed from maleto female-biased across relatively small temporal and spatial scales. Overall it was marginally female-biased, but we estimated an exceptionally high male hatchling production of 47.7% (95% CI: 36.7-58.3%) and 44.5% (95% CI: 33.8-55.4%) in 2013 and 2014, respectively. Both the temporal and spatial variation in incubation conditions and the wide range of the TRT suggest resilience and potential for adaptation to climate change if the present nesting habitat remains unchanged. These findings underline the importance of assessing site-specific parameters to understand populations' responses to climate change, particularly with regard to identifying rookeries with high male hatchling production that may be key for the future conservation of sea turtles under projected global warming scenarios.
Abstract.
Omeyer LCM, Godley BJ, Broderick AC (2017). Growth rates of adult sea turtles.
ENDANGERED SPECIES RESEARCH,
34, 357-371.
Author URL.
Duncan E, Broderick A, Galloway T, Lindeque P, Godley B (2017). Investigating the Presence and Effects of Microplastics in Sea Turtles. In (Ed) Fate and Impact of Microplastics in Marine Ecosystems, Elsevier, 33-34.
Humber F, Godley BJ, Nicolas T, Raynaud O, Pichon F, Broderick A (2017). Placing Madagascar's marine turtle populations in a regional context using community-based monitoring.
ORYX,
51(3), 542-553.
Abstract:
Placing Madagascar's marine turtle populations in a regional context using community-based monitoring
Madagascar is an important foraging ground for marine turtles in the Western Indian Ocean, yet the status of the country's nesting aggregations remains poorly documented. We assess the current status and trend in nesting throughout Madagascar, including data recorded by a community-based monitoring project in the Barren Isles (western Madagascar). We contextualize the findings in comparison with data from Madagascar's closest neighbouring states. Reports indicate that nesting levels have declined at many coastal sites, with no known recordings since 2000 at > 40 nesting sites. We estimate there are a minimum of 1,200 nests per year in Madagascar, with the largest recorded nesting aggregation (< 1,000 nests per year) found on islands off the west and northern coasts. The majority of nesting aggregations, including those recorded by the community-based monitoring project in the Barren Isles, are relatively small, in the order of < 50 nests per year, yet they are potentially important sources of regional genetic diversity. Nesting on many of the islands (e.g. Tromelin, Europa) around Madagascar has increased over the last 20 years, despite the fact that thousands of turtles probably originating from these sites are taken by fishers in the waters of Madagascar annually. We discuss the importance of protecting small nesting populations, and how community-based monitoring could be an important tool for conserving remote and vulnerable populations and building capacity for natural resource management.
Abstract.
Williams SM, Weber SB, Oppel S, Leat EHK, Sommerfeld J, Godley BJ, Weber N, Broderick AC (2017). Satellite Telemetry Reveals the First Record of the Ascension Frigatebird (Fregata aquila) for the Americas.
Wilson Journal of Ornithology,
129(3), 600-604.
Abstract:
Satellite Telemetry Reveals the First Record of the Ascension Frigatebird (Fregata aquila) for the Americas
We present the first record of the Ascension Frigatebird (Fregata aquila) for the Americas by retrieving coordinates from an individual equipped with a satellite transmitting device. As part of a wider study on the spatial and behavioral ecology of this species, we tracked a single juvenile frigatebird that entered into Brazilian waters as defined in the guidelines set forth by the Brazilian Ornithological Records Committee and the South American Checklist Committee. In total, this individual traveled ∼45,000 km over a 3.5-month period before transmissions ceased close to the exclusive economic zone of Sierra Leone. Based on the potential for this species to wander, the Ascension Frigatebird should be considered when attempting to identify any frigatebird in the Atlantic Ocean. Importantly, this record demonstrates the great potential for satellite telemetry to inform national ornithological and conservation organizations on the presence of pelagic seabirds that may otherwise be overlooked by visual surveys.
Abstract.
Bradshaw PJ, Broderick AC, Carreras C, Inger R, Fuller W, Snape R, Stokes KL, Godley BJ (2017). Satellite tracking and stable isotope analysis highlight differential recruitment among foraging areas in green turtles.
Marine Ecology Progress Series,
582, 201-214.
Abstract:
Satellite tracking and stable isotope analysis highlight differential recruitment among foraging areas in green turtles
© the authors 2017. Identifying links between breeding and non-breeding sites in migratory animals is an important step in understanding their ecology. Recognising the relative importance of foraging areas and ascertaining site-specific levels of recruitment can provide fundamental and applied insights. Here, satellite telemetry and the stable isotope ratios (δ13C, δ15N and δ34S) of 230 green turtles Chelonia mydas from a regionally important rookery in northern Cyprus were employed to evaluate the relative importance of 4 foraging areas. A preliminary analysis of stable isotope ratios suggested that a major foraging area had been missed through satellite telemetry as a large proportion of turtles had isotope ratios that did not correspond to sites previously identified. Stable isotope ratios were then employed to select 5 turtles to be fitted with platform terminal transmitters in 2015. All 5 turtles were subsequently tracked to the same location, Lake Bardawil in Egypt. Serially collected tissue samples from 45 females, ranging over 2 to 4 breeding seasons, suggested that foraging site fidelity was very common, with 82% of females exhibiting extremely high temporal consistency in isotope ratios. Quantifying fidelity allowed an evaluation of foraging area-specific contributions to each breeding cohort over the past 2 decades and demonstrated that recruitment was unequal among sites, and dynamic over time, with Egypt now currently the major contributor to the nesting aggregation. This work demonstrates the utility of stable isotope analysis to elucidate the spatial ecology of cryptic taxa and illustrates how more robust baselines can be assembled against which to measure the success of future marine conservation initiatives.
Abstract.
Oppel S, Weber S, Weber N, Fox D, Leat E, Sim J, Sommerfeld J, Bolton M, Broderick AC, Godley BJ, et al (2017). Seasonal shifts in foraging distribution due to individual flexibility in a tropical pelagic forager, the Ascension frigatebird.
Marine Ecology Progress Series,
585, 199-212.
Abstract:
Seasonal shifts in foraging distribution due to individual flexibility in a tropical pelagic forager, the Ascension frigatebird
Predators exploiting tropical pelagic waters characterised by low fluctuations in seasonal temperature and salinity may require different foraging strategies than predators that can rely on persistently productive marine features. Consistent individual differences in foraging strategies have been found in temperate seabirds, but it is unclear whether such foraging special-isation would be beneficial in unpredictable tropical pelagic waters. We examined whether foraging trip characteristics of a tropical seabird were consistent between seasons and within individuals and explored whether seasonal changes could be explained by environmental variables. Ascension frigatebird Fregata aquila trips lasted up to 18 d and covered a total travel distance of up to 7047 km, but adult frigatebirds stayed within a radius of 1150 km of Ascension Island. We found that the 50% utilisation distribution of the population expanded southwestward in the cool season due to individuals performing more and longer trips in a southerly and westerly direction during the cool compared to the hot season. Individual repeatability was low (R < 0.25) for all trip characteristics, and we were unable to explain seasonal changes in time spent at sea using oceanographic or atmospheric variables. Instead, frigatebird usage per area was almost exclusively determined by distance from the colony, and although individuals spent more time in distant portions of their foraging trips, the amount of time spent per unit area decreased exponentially with increasing distance from the colony. This study indicates that, in a relatively featureless environment, high individual consistency may not be a beneficial trait for pelagic predators.
Abstract.
2016
Nelms SE, Duncan EM, Broderick AC, Galloway TS, Godfrey MH, Hamann M, Lindeque PK, Godley BJ (2016). Plastic and marine turtles: a review and call for research.
ICES JOURNAL OF MARINE SCIENCE,
73(2), 165-181.
Author URL.
Rees AF, Alfaro-Shigueto J, Barata PCR, Bjorndal KA, Bolten AB, Bourjea J, Broderick AC, Campbell LM, Cardona L, Carreras C, et al (2016). Review: Are we working towards global research priorities for management and conservation of sea turtles?. Endangered Species Research, 31, 337-382.
Snape RTE, Broderick AC, Çiçek BA, Fuller WJ, Glen F, Stokes K, Godley BJ (2016). Shelf life: Neritic habitat use of a turtle population highly threatened by fisheries.
Diversity and Distributions,
22(7), 797-807.
Abstract:
Shelf life: Neritic habitat use of a turtle population highly threatened by fisheries
Aim: it is difficult to mitigate threats to marine vertebrates until their habitat use is understood. We report on a decade of satellite tracking loggerhead turtles (Caretta caretta) from an important nesting site to determine priority habitats for their protection in a region where they are known to be heavily impacted by fisheries. Location: Cyprus, Eastern Mediterranean. Method: We tracked 27 adult female loggerheads between 2001 and 2012 from North Cyprus nesting beaches. To eliminate potential biases, we included females nesting on all coasts of our study area, at different periods of the nesting season and from a range of size classes. Results: Foraging sites were distributed over the continental shelf of Cyprus, the Levant and North Africa, up to a maximum distance of 2100 km from nesting sites. Foraging sites were clustered in (1) near-shore waters of Cyprus and Syria, (2) offshore waters of Egypt and (3) offshore and near-shore regions of Libya and Tunisia. The North Cyprus and west Egypt/east Libyan coasts are important areas for loggerhead turtles during migration. Movement patterns within foraging sites strongly suggest benthic feeding in discrete areas. Early nesters visited other rookeries in Turkey, Syria and Israel where they likely laid further clutches. Tracking suggests minimum annual mortality of 11%, comparable to other fishery-impacted loggerhead populations. Main conclusions: This work further highlights the importance of neritic habitats of Libya and Tunisia as areas likely used by loggerhead turtles from many of the Mediterranean rookeries and where the threat of fisheries bycatch is high. Our tracking data also suggest that anthropogenic mortalities may have occurred in North Cyprus, Syria and Egypt; all within near-shore marine areas where small-scale fisheries operate. Protection of this species across many geopolitical units is a major challenge and documenting their distribution is an important first step.
Abstract.
Hawkes LA, Witt MJ, Godley BJ, Broderick AC, McGowan A, Bjorndal KA, Bolten AB, Chaloupka M, Van Dam RP, Diez CE, et al (2016). Somatic growth dynamics of West Atlantic hawksbill sea turtles: a spatio-temporal perspective. Ecosphere, 7
Stringell TB, Clerveaux WV, Godley BJ, Kent FEA, Lewis EDG, Marsh JE, Phillips Q, Richardson PB, Sanghera A, Broderick AC, et al (2016). Taxonomic distinctness in the diet of two sympatric marine turtle species.
Marine Ecology,
37(5), 1036-1049.
Abstract:
Taxonomic distinctness in the diet of two sympatric marine turtle species
Marine turtles are considered keystone consumers in tropical coastal ecosystems and their decline through overexploitation has been implicated in the deterioration of reefs and seagrass pastures in the Caribbean. In the present study, we analysed stomach contents of green (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata) harvested in the legal turtle fishery of the Turks and Caicos Islands (Caribbean) during 2008–2010. Small juveniles to adult-sized turtles were sampled. Together with data from habitat surveys, we assessed diet composition and the taxonomic distinctness (and other species diversity measures) in the diets of these sympatric marine turtle species. The diet of green turtles (n�=�92) consisted of a total of 47 taxa: including three species of seagrass (present in 99% of individuals), 29 species of algae and eight sponge species. Hawksbill turtles (n�=�45) consumed 73 taxa and were largely spongivorous (16 species; sponges present in 100% of individuals) but also foraged on 50 species of algae (present in 73% of individuals) and three species of seagrass. Plastics were found in trace amounts in 4% of green turtle and 9% of hawksbill turtle stomach samples. We expected to find changes in diet that might reflect ontogenetic shifts from small (oceanic-pelagic) turtles to larger (coastal-benthic) turtles. Dietary composition (abundance and biomass), however, did not change significantly with turtle size, although average taxonomic distinctness was lower in larger green turtles. There was little overlap in prey between the two turtle species, suggesting niche separation. Taxonomic distinctness routines indicated that green turtles had the most selective diet, whereas hawksbill turtles were less selective than expected when compared with the relative frequency and biomass of diet items. We discuss these findings in relation to the likely important trophic roles that these sympatric turtle species play in reef and seagrass habitats.
Abstract.
2015
Revuelta O, León YM, Broderick AC, Feliz P, Godley BJ, Balbuena JA, Mason A, Poulton K, Savoré S, Raga JA, et al (2015). Assessing the efficacy of direct conservation interventions: Clutch protection of the leatherback marine turtle in the Dominican Republic.
ORYX,
49(4), 677-686.
Abstract:
Assessing the efficacy of direct conservation interventions: Clutch protection of the leatherback marine turtle in the Dominican Republic
The beaches of Jaragua National Park in the Dominican Republic are the country's last known major nesting site for the leatherback marine turtle Dermochelys coriacea. This nesting aggregation is threatened by widespread illegal egg take, and clutch relocation and artificial incubation have been carried out as protection measures since 1974. We assess the efficacy of such efforts and investigate how artificial incubation may be influencing the success and sex ratios of clutches. We compare hatching success, incubation duration and embryo mortality in in-situ clutches (n = 43) with those incubated artificially at sites in the east and west of the Park (n = 35 and n = 31, respectively). Our results show that in the west, artificial incubation significantly decreases hatching success in clutches. In the east the duration of incubation is increased, which we predict would result in an increase in the number of males from these clutches. Clutch relocation is currently the only viable conservation option for clutches on eastern beaches because of illegal egg take but action is needed to ensure that the natural sex ratio is not distorted. However, on the western beaches in situ clutch incubation seems possible through beach protection. Further community engagement and enforcement are required to improve conservation measures at eastern beaches if long-term, less sustainable intervention is to be avoided.
Abstract.
Humber F, Andriamahefazafy M, Godley BJ, Broderick AC (2015). Endangered, essential and exploited: How extant laws are not enough to protect marine megafauna in Madagascar.
Marine Policy,
60, 70-83.
Abstract:
Endangered, essential and exploited: How extant laws are not enough to protect marine megafauna in Madagascar
The decline of many marine megafauna species is of global concern; but many of these species, in particular marine mammals, have been afforded international and national protection and are the focus of conservation programmes. The existing national and international legislation are reviewed through which marine megavertebrates are afforded protection in Malagasy waters. The decline and protection of marine megafauna has followed a familiar pattern in Madagascar, with two main exceptions: marine turtles and elasmobranchs remain heavily exploited by national and international fishing fleets. The status of legislation governing both taxa is unclear and unknown by many working within the fisheries and marine sector. In Madagascar, marine turtles are fully protected from exploitation by national regulations in conjunction with a number of multilateral agreements. The numerous pieces of legislation that protect marine turtles are not coherent, regularly misunderstood and rarely enforced. Madagascar is taking steps to improve protection of marine turtles through the development of a national strategy, but it is recommended that the opportunity is also taken to improve understanding of current legislation and work more closely with local communities that consider turtle fishing a customary practice. Elasmobranchs however, receive minimal legal protection and only those listed under multilateral agreements are bound by any potential future management. Where legislation does exist to help manage elasmobranchs (eg. bycatch stipulations for foreign fishing vessels) it is incomplete and difficult to enforce. It is also recommended that Madagascar puts in place national elasmobranch legislation to help prevent their continued overfishing, especially in the face of increasing numbers of elasmobranch species on CITES and CMS. As such, both groups of species are rendered effectively unprotected and are in danger of overexploitation. With the growth and proliferation of locally managed marine areas (LMMAs) in Madagascar the potential for local communities to increase protection and management of these species should be considered, especially with the limited capacity available to monitor and enforce legislation along such a vast coastline.
Abstract.
Hammerschlag N, Broderick AC, Coker JW, Coyne MS, Dodd M, Frick MG, Godfrey MH, Godley BJ, Griffin DB, Hartog K, et al (2015). Evaluating the landscape of fear between apex predatory sharks and mobile sea turtles across a large dynamic seascape.
Ecology,
96(8), 2117-2126.
Abstract:
Evaluating the landscape of fear between apex predatory sharks and mobile sea turtles across a large dynamic seascape
The “landscape of fear” model has been proposed as a unifying concept in ecology, describing, in part, how animals behave and move about in their environment. The basic model predicts that as an animal's landscape changes from low to high risk of predation, prey species will alter their behavior to risk avoidance. However, studies investigating and evaluating the landscape of fear model across large spatial scales (tens to hundreds of thousands of square kilometers) in dynamic, open, aquatic systems involving apex predators and highly mobile prey are lacking. To address this knowledge gap, we investigated predator–prey relationships between tiger sharks (Galeocerdo cuvier) and loggerhead turtles (Caretta caretta) in the North Atlantic Ocean. This included the use of satellite tracking to examine shark and turtle distributions as well as their surfacing behaviors under varying levels of home range overlap. Our findings revealed patterns that deviated from our a priori predictions based on the landscape of fear model. Specifically, turtles did not alter their surfacing behaviors to risk avoidance when overlap in shark–turtle core home range was high. However, in areas of high overlap with turtles, sharks exhibited modified surfacing behaviors that may enhance predation opportunity. We suggest that turtles may be an important factor in determining shark distribution, whereas for turtles, other life history trade‐offs may play a larger role in defining their habitat use. We propose that these findings are a result of both biotic and physically driven factors that independently or synergistically affect predator–prey interactions in this system. These results have implications for evolutionary biology, community ecology, and wildlife conservation. Further, given the difficulty in studying highly migratory marine species, our approach and conclusions may be applied to the study of other predator–prey systems.
Abstract.
Stringell TB, Clerveaux WV, Godley BJ, Phillips Q, Ranger S, Richardson PB, Sanghera A, Broderick AC (2015). Fisher choice may increase prevalence of green turtle fibropapillomatosis disease. Frontiers in Marine Science, 2
Broderick AC (2015). Grand challenges in marine conservation and sustainable use. Frontiers in Marine Science, 2
Stokes KL, Broderick AC, Canbolat AF, Candan O, Fuller WJ, Glen F, Levy Y, Rees AF, Rilov G, Snape RT, et al (2015). Migratory corridors and foraging hotspots: Critical habitats identified for Mediterranean green turtles.
Diversity and DistributionsAbstract:
Migratory corridors and foraging hotspots: Critical habitats identified for Mediterranean green turtles
Levels of sea turtle bycatch in the Mediterranean are thought to be unsustainable. We provide a comprehensive overview of adult green turtle (Chelonia mydas) distribution during nesting, migration and foraging phases, highlighting transitory as well as residential areas of high use to facilitate adequate protection for this long-lived, migratory species. Location: Mediterranean Sea. Methods: Thirty-four females were satellite tracked from breeding grounds in the four countries with major nesting (Cyprus, Turkey, Israel and Syria) for a total of 8521 (mean: 251) tracking days in a collaborative effort to summarize the most comprehensive set of distribution data thus far assembled for this species in the Mediterranean. Results: Ten foraging grounds are identified, with two major hotspots in Libya accounting for >50% of turtles tracked to conclusive endpoints. The coastlines of Egypt and Libya contain high densities of migrating turtles following the nesting season, particularly July-September, and likely also pre-nesting (April-June). A high-use seasonal pelagic corridor running south-west from Turkey and Cyprus to Egypt is also evident, used by >50% of all tracked turtles. Main conclusions: Bycatch levels and mortality rates for the key foraging areas and high-density seasonal pathways identified here are largely unknown and should be investigated as a priority. We recommend that the Gulf of Sirte in Libya be explored as a potential biodiversity hotspot and considered for proposal as a marine protected area (MPA). Green turtle fidelity to nesting beaches, foraging areas and migratory pathways renders them vulnerable to localized threats but enables targeted mitigation measures and protection.
Abstract.
Stokes KL, Broderick AC, Canbolat AF, Candan O, Fuller WJ, Glen F, Levy Y, Rees AF, Rilov G, Snape RT, et al (2015). Migratory corridors and foraging hotspots: Critical habitats identified for Mediterranean green turtles.
Diversity and Distributions,
21(6), 665-674.
Abstract:
Migratory corridors and foraging hotspots: Critical habitats identified for Mediterranean green turtles
Aim: Levels of sea turtle bycatch in the Mediterranean are thought to be unsustainable. We provide a comprehensive overview of adult green turtle (Chelonia mydas) distribution during nesting, migration and foraging phases, highlighting transitory as well as residential areas of high use to facilitate adequate protection for this long-lived, migratory species. Location: Mediterranean Sea. Methods: Thirty-four females were satellite tracked from breeding grounds in the four countries with major nesting (Cyprus, Turkey, Israel and Syria) for a total of 8521 (mean: 251) tracking days in a collaborative effort to summarize the most comprehensive set of distribution data thus far assembled for this species in the Mediterranean. Results: Ten foraging grounds are identified, with two major hotspots in Libya accounting for >50% of turtles tracked to conclusive endpoints. The coastlines of Egypt and Libya contain high densities of migrating turtles following the nesting season, particularly July-September, and likely also pre-nesting (April-June). A high-use seasonal pelagic corridor running south-west from Turkey and Cyprus to Egypt is also evident, used by >50% of all tracked turtles. Main conclusions: Bycatch levels and mortality rates for the key foraging areas and high-density seasonal pathways identified here are largely unknown and should be investigated as a priority. We recommend that the Gulf of Sirte in Libya be explored as a potential biodiversity hotspot and considered for proposal as a marine protected area (MPA). Green turtle fidelity to nesting beaches, foraging areas and migratory pathways renders them vulnerable to localized threats but enables targeted mitigation measures and protection.
Abstract.
Pikesley SK, Broderick AC, Cejudo D, Coyne MS, Godfrey MH, Godley BJ, Lopez P, López-Jurado LF, Elsy Merino S, Varo-Cruz N, et al (2015). Modelling the niche for a marine vertebrate: a case study incorporating behavioural plasticity, proximate threats and climate change.
Ecography,
38(8), 803-812.
Abstract:
Modelling the niche for a marine vertebrate: a case study incorporating behavioural plasticity, proximate threats and climate change
The integration of satellite telemetry, remotely sensed environmental data, and habitat/environmental modelling has provided for a growing understanding of spatial and temporal ecology of species of conservation concern. The Republic of Cape Verde comprises the only substantial rookery for the loggerhead turtle Caretta caretta in the eastern Atlantic. A size related dichotomy in adult foraging patterns has previously been revealed for adult sea turtles from this population with a proportion of adults foraging neritically, whilst the majority forage oceanically. Here we describe observed habitat use and employ ecological niche modelling to identify suitable foraging habitats for animals utilising these two distinct behavioural strategies. We also investigate how these predicted habitat niches may alter under the influence of climate change induced oceanic temperature rises. We further contextualise our niche models with fisheries catch data and knowledge of fisheries 'hotspots' to infer threat from fisheries interaction to this population, for animals employing both strategies. Our analysis revealed repeated use of coincident oceanic habitat, over multiple seasons, by all smaller loggerhead turtles, whilst larger neritic foraging turtles occupied continental shelf waters. Modelled habitat niches were spatially distinct, and under the influence of predicted sea surface temperature rises, there was further spatial divergence of suitable habitats. Analysis of fisheries catch data highlighted that the observed and modelled habitats for oceanic and neritic loggerhead turtles could extensively interact with intensive fisheries activity within oceanic and continental shelf waters of northwest Africa. We suggest that the development and enforcement of sustainable management strategies, specifically multi-national fisheries policy, may begin to address some of these issues; however, these must be flexible and adaptive to accommodate potential range shift for this species.
Abstract.
2014
Revuelta O, León YM, Broderick AC, Feliz P, Godley BJ, Balbuena JA, Mason A, Poulton K, Savoré S, Raga JA, et al (2014). Assessing the efficacy of direct conservation interventions: clutch protection of the leatherback marine turtle in the Dominican Republic.
ORYXAbstract:
Assessing the efficacy of direct conservation interventions: clutch protection of the leatherback marine turtle in the Dominican Republic
The beaches of Jaragua National Park in the Dominican Republic are the country's last known major nesting site for the leatherback marine turtle Dermochelys coriacea. This nesting aggregation is threatened by widespread illegal egg take, and clutch relocation and artificial incubation have been carried out as protection measures since 1974. We assess the efficacy of such efforts and investigate how artificial incubation may be influencing the success and sex ratios of clutches. We compare hatching success, incubation duration and embryo mortality in in-situ clutches (n = 43) with those incubated artificially at sites in the east and west of the Park (n = 35 and n = 31, respectively). Our results show that in the west, artificial incubation significantly decreases hatching success in clutches. In the east the duration of incubation is increased, which we predict would result in an increase in the number of males from these clutches. Clutch relocation is currently the only viable conservation option for clutches on eastern beaches because of illegal egg take but action is needed to ensure that the natural sex ratio is not distorted. However, on the western beaches in situ clutch incubation seems possible through beach protection. Further community engagement and enforcement are required to improve conservation measures at eastern beaches if long-term, less sustainable intervention is to be avoided. Copyright © Fauna & Flora International 2014.
Abstract.
Stokes KL, Fuller WJ, Glen F, Godley BJ, Hodgson DJ, Rhodes KA, Snape RTE, Broderick AC (2014). Detecting green shoots of recovery: the importance of long-term individual-based monitoring of marine turtles.
Animal Conservation,
17(6), 593-602.
Abstract:
Detecting green shoots of recovery: the importance of long-term individual-based monitoring of marine turtles
Population monitoring is an essential part of evaluating the effectiveness of management interventions for conservation. Coastal breeding aggregations of marine vertebrate species that come ashore to pup or nest provide an opportunistic window of observation into otherwise widely dispersed populations. Green turtle (Chelonia mydas) nesting on the north and west coasts of northern Cyprus has been monitored consistently and exhaustively since 1993, with an intensive saturation tagging programme running at one key site for the same duration. This historically depleted nesting population is showing signs of recovery, possibly in response to nest protection approaching two decades, with increasing nest numbers and rising levels of recruitment. Strong correlation between year-to-year magnitude of nesting and the proportion of new breeders in the nesting cohort implies that recruitment of new individuals to the breeding population is an important driver of this recovery trend. Recent changes in fishing activities may be impacting the local juvenile neritic stage, however, which may hinder this potential recovery. Individuals returning to breed after two years laid fewer clutches than those returning after three or four years, demonstrating a trade-off between remigration interval and breeding output. Average clutch frequencies have remained stable around a median of three clutches a year per female despite the demographic shift towards new nesters, which typically lay fewer clutches in their first season. We show that where local fecundity has been adequately assessed, the use of average clutch frequencies can be a reliable method for deriving nester abundance from nest counts. Index sites where individual-based monitoring is possible will be important in monitoring long-term climate driven changes in reproductive rates.
Abstract.
Hawkes LA, Mcgowan A, Broderick AC, Gore S, Wheatley D, White J, Witt MJ, Godley BJ (2014). High rates of growth recorded for hawksbill sea turtles in Anegada, British Virgin Islands.
Ecology and Evolution,
4(8), 1255-1266.
Abstract:
High rates of growth recorded for hawksbill sea turtles in Anegada, British Virgin Islands
Management of species of conservation concern requires knowledge of demographic parameters, such as rates of recruitment, survival, and growth. In the Caribbean, hawksbill turtles (Eretmochelys imbricata) have been historically exploited in huge numbers to satisfy trade in their shells and meat. In the present study, we estimated growth rate of juvenile hawksbill turtles around Anegada, British Virgin Islands, using capture-mark-recapture of 59 turtles over periods of up to 649 days. Turtles were recaptured up to six times, having moved up to 5.9 km from the release location. Across all sizes, turtles grew at an average rate of 9.3 cm year-1 (range 2.3-20.3 cm year-1), and gained mass at an average of 3.9 kg year-1 (range 850 g-16.1 kg year-1). Carapace length was a significant predictor of growth rate and mass gain, but there was no relationship between either variable and sea surface temperature. These are among the fastest rates of growth reported for this species, with seven turtles growing at a rate that would increase their body size by more than half per year (51-69% increase in body length). This study also demonstrates the importance of shallow water reef systems for the developmental habitat for juvenile hawksbill turtles. Although growth rates for posthatching turtles in the pelagic, and turtles larger than 61 cm, are not known for this population, the implications of this study are that Caribbean hawksbill turtles in some areas may reach body sizes suggesting sexual maturity in less time than previously considered. In the present study, we estimated growth rate of juvenile hawksbill turtles around Anegada, British Virgin Islands, using capture-mark-recapture of 59 turtles over periods of up to 649 days. Across all sizes, turtles grew at an average rate of 9.3 cm per year (range 2.3-20.3 cm year-1), and gained mass at an average of 3.9 kg year-1 (range 850 g-16.1 kg year-1). These are among the fastest rates of growth reported for this species, with seven turtles growing at a rate that would increase their body size by more than half per year (51-69% increase in body length). © 2014 the Authors. Ecology and Evolution published by John Wiley & Sons Ltd.
Abstract.
Carreras C, Rees AF, Broderick AC, Godley BJ, Margaritoulis D (2014). Mitochondrial DNA markers of loggerhead marine turtles (<i>Caretta caretta</i>) (Testudines: Cheloniidae) nesting at Kyparissia Bay, Greece, confirm the western Greece unit and regional structuring.
SCIENTIA MARINA,
78(1), 115-124.
Author URL.
Carreras C, Rees AF, Broderick AC, Godley BJ, Margaritoulis D (2014). Mitochondrial DNA markers of loggerhead marine turtles (Caretta caretta) (Testudines: Cheloniidae) nesting at Kyparissia Bay, Greece, confirm the western Greece unit and regional structuring.
Scientia Marina,
78(1), 115-124.
Abstract:
Mitochondrial DNA markers of loggerhead marine turtles (Caretta caretta) (Testudines: Cheloniidae) nesting at Kyparissia Bay, Greece, confirm the western Greece unit and regional structuring
Genetic markers have been widely used in marine turtles to assess population structuring and origin of individuals in common feeding grounds, which are key elements for understanding their ecology and for developing conservation strategies. However, these analyses are very sensitive to missing information, especially from abundant nesting sites. Kyparissia Bay (western Greece) hosts the second largest Mediterranean nesting aggregation of the loggerhead turtle (Caretta caretta), but the genetic profile of this nesting site has not, as yet, been described using the extended version of the historically used mitochondrial DNA (mtDNA) marker. This marker was genotyped for 36 individuals nesting at Kyparissia Bay and haplotype frequencies obtained were compared with published data from other Mediterranean nesting sites. The results confirmed the connection between Kyparissia and other western Greek nesting sites and the isolation of this western Greek group from other Mediterranean nesting areas. As a consequence of this isolation, this abundant group of nesting aggregations (almost 30% of the Mediterranean stock) is not likely to significantly contribute to the recovery of other declining Mediterranean units. © 2014 CSIC.
Abstract.
Pikesley SK, Broderick AC, Cejudo D, Coyne MS, Godfrey MH, Godley BJ, Lopez P, López-Jurado LF, Elsy Merino S, Varo-Cruz N, et al (2014). Modelling the niche for a marine vertebrate: a case study incorporating behavioural plasticity, proximate threats and climate change. Ecography
Putman NF, Abreu-Grobois FA, Broderick AC, Ciofi C, Formia A, Godley BJ, Stroud S, Pelembe T, Verley P, Williams N, et al (2014). Numerical dispersal simulations and genetics help explain the origin of hawksbill sea turtles in Ascension Island.
Journal of Experimental Marine Biology and Ecology,
450, 98-108.
Abstract:
Numerical dispersal simulations and genetics help explain the origin of hawksbill sea turtles in Ascension Island
Long-distance dispersal and ontogenetic shifts in habitat use are characteristic of numerous marine species and have important ecological, evolutionary, and management implications. These processes, however, are often challenging to study due to the vast areas involved. We used genetic markers and simulations of physical transport within an ocean circulation model to gain understanding into the origin of juvenile hawksbill sea turtles (. Eretmochelys imbricata) found at Ascension Island, a foraging ground that is thousands of kilometers from known nesting beaches. Regional origin of genetic markers suggests that turtles are from Western Atlantic (86%) and Eastern Atlantic (14%) rookeries. In contrast, numerical simulations of transport by ocean currents suggest that passive dispersal from the western sources would be negligible and instead would primarily be from the East, involving rookeries along Western Africa (i.e. Principe Island) and, potentially, from as far as the Indian Ocean (e.g. Mayotte and the Seychelles). Given that genetic analysis identified the presence of a haplotype endemic to Brazilian hawksbill rookeries at Ascension, we examined the possible role of swimming behavior by juvenile hawksbills from NE Brazil on their current-borne transport to Ascension Island by performing numerical experiments in which swimming behavior was simulated for virtual particles (simulated turtles). We found that oriented swimming substantially influenced the distribution of particles, greatly altering the proportion of particles dispersing into the North Atlantic and South Atlantic. Assigning location-dependent orientation behavior to particles allowed them to reach Ascension Island, remain in favorable temperatures, encounter productive foraging areas, and return to the vicinity of their natal site. The age at first arrival to Ascension (4.5-5.5. years) of these particles corresponded well to estimates of hawksbill age based on their size. Our findings suggest that ocean currents and swimming behavior play an important role in the oceanic ecology of sea turtles and other marine animals. © 2013 Elsevier B.V.
Abstract.
Fossette S, Witt MJ, Miller P, Nalovic MA, Albareda D, Almeida AP, Broderick AC, Chacón-Chaverri D, Coyne MS, Domingo A, et al (2014). Pan-atlantic analysis of the overlap of a highly migratory species, the leatherback turtle, with pelagic longline fisheries.
Proc Biol Sci,
281(1780).
Abstract:
Pan-atlantic analysis of the overlap of a highly migratory species, the leatherback turtle, with pelagic longline fisheries.
Large oceanic migrants play important roles in ecosystems, yet many species are of conservation concern as a result of anthropogenic threats, of which incidental capture by fisheries is frequently identified. The last large populations of the leatherback turtle, Dermochelys coriacea, occur in the Atlantic Ocean, but interactions with industrial fisheries could jeopardize recent positive population trends, making bycatch mitigation a priority. Here, we perform the first pan-Atlantic analysis of spatio-temporal distribution of the leatherback turtle and ascertain overlap with longline fishing effort. Data suggest that the Atlantic probably consists of two regional management units: northern and southern (the latter including turtles breeding in South Africa). Although turtles and fisheries show highly diverse distributions, we highlight nine areas of high susceptibility to potential bycatch (four in the northern Atlantic and five in the southern/equatorial Atlantic) that are worthy of further targeted investigation and mitigation. These are reinforced by reports of leatherback bycatch at eight of these sites. International collaborative efforts are needed, especially from nations hosting regions where susceptibility to bycatch is likely to be high within their exclusive economic zone (northern Atlantic: Cape Verde, Gambia, Guinea Bissau, Mauritania, Senegal, Spain, USA and Western Sahara; southern Atlantic: Angola, Brazil, Namibia and UK) and from nations fishing in these high-susceptibility areas, including those located in international waters.
Abstract.
Author URL.
Weber SB, Weber N, Ellick J, Avery A, Frauenstein R, Godley BJ, Sim J, Williams N, Broderick AC (2014). Recovery of the South Atlantic's largest green turtle nesting population.
BIODIVERSITY AND CONSERVATION,
23(12), 3005-3018.
Author URL.
Humber F, Godley BJ, Broderick AC (2014). So excellent a fishe: a global overview of legal marine turtle fisheries.
Diversity and Distributions,
20(5), 579-590.
Abstract:
So excellent a fishe: a global overview of legal marine turtle fisheries
Aim: We provide a global assessment of the current legal direct take of marine turtles, including the scale and species breakdown at country level, and investigate the significance of legal take to marine turtle populations within the wider context of global threats. Location: World-wide. Methods: We undertook a comprehensive review of the literature (>500 publications) and contacted over 150 in-country experts to collate data for countries that permit the legal take of marine turtles (as of 1 January 2013). Current annual take for each country and species was estimated, and estimates were generated for the 1980s, 1990s and 2000s. Results: Currently, 42 countries and territories permit direct take of turtles and collectively take in excess of 42,000turtles per year, the majority of which (>80%) are green turtles Chelonia mydas (Linnaeus 1758). Ten countries account for more than 90% of legal take each year with Papua New Guinea (36.1%) and Nicaragua (22.3%) accounting for more than half of the total global take. Since 1980, we estimate that more than 2million turtles have been legally taken in these countries, with current levels
Abstract.
Humber F, Godley BJ, Broderick AC (2014). So excellent a fishe: a global overview of legal marine turtle fisheries. Diversity and Distributions
Horne CR, Fuller WJ, Godley BJ, Rhodes KA, Snape R, Stokes KL, Broderick AC (2014). The effect of thermal variance on the phenotype of marine turtle offspring.
Physiol Biochem Zool,
87(6), 796-804.
Abstract:
The effect of thermal variance on the phenotype of marine turtle offspring.
Temperature can have a profound effect on the phenotype of reptilian offspring, yet the bulk of current research considers the effects of constant incubation temperatures on offspring morphology, with few studies examining the natural thermal variance that occurs in the wild. Over two consecutive nesting seasons, we placed temperature data loggers in 57 naturally incubating clutches of loggerhead sea turtles Caretta caretta and found that greater diel thermal variance during incubation significantly reduced offspring mass, potentially reducing survival of hatchlings during their journey from the nest to offshore waters and beyond. With predicted scenarios of climate change, behavioral plasticity in nest site selection may be key for the survival of ectothermic species, particularly those with temperature-dependent sex determination.
Abstract.
Author URL.
Hawkes LA, Broderick AC, Godfrey MH, Godley BJ, Witt MJ (2014). The impacts of climate change on marine turtle reproductive success. In (Ed) Coastal Conservation, Cambridge University Press, 287-310.
Revuelta O, León YM, Balbuena JA, Broderick AC, Feliz P, Godley BJ, Raga JA, Tomás J (2014). The value of endangered species in protected areas at risk: the case of the leatherback turtle in the Dominican Republic.
Biodiversity and Conservation,
23(6), 1529-1539.
Abstract:
The value of endangered species in protected areas at risk: the case of the leatherback turtle in the Dominican Republic
Protected areas are considered essential elements for global biodiversity conservation. They may not necessarily result in an effective conservation of resources in developing countries due to lack of funding for management and enforcement. In addition, poor governance aligned with conflicts of economic interests related to their use can further threaten their integrity and persistence. In the Dominican Republic, the western beaches of the Jaragua National Park (JNP), a protected area which is also part of a UNESCO Biosphere Reserve, have been proposed for development using a mass-tourism model. One of the most charismatic species found in this area is the leatherback turtle (Dermochelys coriacea). In the present study, we assess hatching success, and factors affecting it, to determine the reproductive value across the area for the leatherback turtle. The main factors found driving hatching success at the study beaches are beach sector, incubation duration, date of lay and clutch size. Our results show that clutches in La Cueva (located in the buffer zone of the park) and Bahía de las Águilas (located inside the limits of the park) have an unusually high hatching success (~75 %) for this species, highlighting the importance of increasing protection efforts at these sites. We strongly recommend including La Cueva inside the limits of the JNP. © 2014 Springer Science+Business Media Dordrecht.
Abstract.
Revuelta O, León YM, Balbuena JA, Broderick AC, Feliz P, Godley BJ, Raga JA, Tomás J (2014). The value of endangered species in protected areas at risk: the case of the leatherback turtle in the Dominican Republic. Biodiversity and Conservation
2013
Hawkes LA, McGowan A, Godley BJ, Gore S, Lange A, Tyler CR, Wheatley D, White J, Witt MJ, Broderick AC, et al (2013). Estimating sex ratios in Caribbean hawksbill turtles: Testosterone levels and climate effects.
Aquatic Biology,
18(1), 9-19.
Abstract:
Estimating sex ratios in Caribbean hawksbill turtles: Testosterone levels and climate effects
Evolutionary theory predicts that male and female offspring should be produced at a 1:1 ratio, but this may rarely be the case for species in which sex is determined during incubation by temperature, such as marine turtles. Estimates of primary sex ratio suggest that marine turtle sex ratios are highly skewed, with up to 9 females per male. We captured juvenile hawksbill turtles Eretmochelys imbricata in waters around Anegada, British Virgin Islands, a regionally important foraging aggregation, and analysed concentrations of plasma testosterone and oestradiol- 17β from 62 turtles to estimate sex ratio. There were 2.4 to 7.7 times more females than males. Testosterone concentrations correlated with sampling date and sea surface temperature (SST), with higher con centrations in the late summer when SST was highest, suggesting that assigning sex through threshold values of sex hormones must be carried out cautiously. The sex ratio in the juvenile foraging aggregation around Anegada is more male biased than at other locations, suggesting that turtles at Anegada have resilience against feminising effects of climate change. Future work should (1) integrate the relative contributions of different genetic stocks to foraging aggregations and (2) investigate the annual and seasonal cycles of sex hormones, and differences among individuals and life history stages. © Inter-Research 2013.
Abstract.
Griffin DBB, Murphy SR, Frick MG, Broderick AC, Coker JW, Coyne MS, Dodd MG, Godfrey MH, Godley BJ, Hawkes LA, et al (2013). Foraging habitats and migration corridors utilized by a recovering subpopulation of adult female loggerhead sea turtles: Implications for conservation.
Marine Biology,
160(12), 3071-3086.
Abstract:
Foraging habitats and migration corridors utilized by a recovering subpopulation of adult female loggerhead sea turtles: Implications for conservation
From 1998 to 2008, 68 adult female loggerhead sea turtles (Caretta caretta) were instrumented with platform transmitter terminals at nesting beaches in Georgia, North Carolina (NC) and South Carolina (SC) on the East Coast of the United States of America (30°48′N, 81°28′W to 33°51′N, 77°59′W). The majority of post-nesting loggerheads (N = 42, 62 %) migrated to foraging habitats in the Mid-Atlantic Bight during May-October, with a subsequent migration occurring during November-March to foraging habitats south of Cape Hatteras, NC. Nine (13 %) loggerheads initially foraged in the near-shore, coastal areas of the South Atlantic Bight, but moved to offshore habitats-closer to the Gulf Stream-during November-March, while fourteen (21 %) loggerheads remained in foraging areas along the mid-continental shelf off of the eastern coast of Florida and/or continued southward to Florida Bay and the Bahamas. The present study delineates important, post-nesting foraging habitats and migration corridors where loggerheads may interact with commercial fisheries-providing managers opportunities to develop and implement optimally effective conservation actions for the recovery of this threatened species. © 2013 Springer-Verlag Berlin Heidelberg.
Abstract.
Griffin DB, Murphy SR, Frick MG, Broderick AC, Coker JW, Coyne MS, Dodd MG, Godfrey MH, Godley BJ, Hawkes LA, et al (2013). Foraging habitats and migration corridors utilized by a recovering subpopulation of adult female loggerhead sea turtles: implications for conservation. Marine Biology, 1-16.
Fuller WJ, Godley BJ, Hodgson DJ, Reece SE, Witt MJ, Broderick AC (2013). Importance of spatio-temporal data for predicting the effects of climate change on marine turtle sex ratios.
Marine Ecology Progress Series,
488, 267-274.
Abstract:
Importance of spatio-temporal data for predicting the effects of climate change on marine turtle sex ratios
Species with temperature-dependent sex determination (TSD) are likely to be impacted by climate change. There is a paucity of data on the contemporary sex ratios of offspring produced by regional marine turtle populations. The lack of such information inhibits the ability of researchers to accurately predict how future meteorological and climate-driven changes may affect turtle populations. Moreover, these data are integral for the development of regional and global recovery plans for declining turtle populations. We estimate offspring sex ratios for the loggerhead turtle Caretta caretta at a range of beaches on the Mediterranean island of Cyprus over a 10 yr period (1997 to 2006; 40 beaches, 628 clutches, 29402 hatchlings). Based on hatchling sex determination, we found the pivotal incubation temperature (the temperature at which a 50:50 sex ratio occurs) to be 28.9°C, and the pivotal incubation duration to be 56.3 d. From the incubation durations of over 628 in situ clutches laid on different beaches, we estimate that 89% of the offspring produced from these clutches were female. There was, however, both inter-annual (74 to 95% female) and inter-beach (58-98% female) variability in mean offspring sex ratios. These findings highlight the need for wide-scale, long-term monitoring of primary sex ratios in order to accurately predict the likely impacts of climate change. Despite spatial and temporal variation in offspring sex ratios produced, male hatchlings are certainly in the minority in Cyprus. It is therefore highly likely that beaches producing males will become increasingly critical habitats for successful clutch incubation in the face of predicted rising temperatures. © Inter-Research 2013.
Abstract.
Richardson PB, Broderick AC, Coyne MS, Gore S, Gumbs JC, Pickering A, Ranger S, Witt MJ, Godley BJ (2013). Leatherback turtle conservation in the Caribbean UK overseas territories: Act local, think global?.
Marine Policy,
38, 483-490.
Abstract:
Leatherback turtle conservation in the Caribbean UK overseas territories: Act local, think global?
Leatherback turtles migrate across the jurisdictions of multiple sovereign states and present complex challenges to those responsible for their conservation. Concern for marine turtles has led to their protection under range state legislation and protective listing under a suite of multilateral environmental agreements. Evidence suggests that a distinct, reproductive sub-population of leatherback turtles is shared amongst a number of northern Caribbean range states, including the UK overseas territories (UKOTs) of Anguilla and the British Virgin Islands (BVI). The post-nesting movements of three female leatherbacks were tracked after they nested in Anguilla (n=1, tracked for 228 days) and the BVI (n=2, tracked for 12 and 13 days, respectively). These turtles used territories of multiple range states, with the leatherback tracked from Anguilla also migrating through high seas to foraging grounds in Canadian waters. In addition, a review of regional leatherback flipper tag return records helps define the range of this northern Caribbean nesting population (NCNP), which appears to be in recovery in some range states. While national legislation and conservation efforts appear to have contributed to these population recoveries, most relevant MEAs appear to have played little or no role. However, opportunities for constructive dialogue between NCNP range states exist under the Cartagena Convention the United Nations Convention on the Law of the Sea and the International Commission for the Conservation of Atlantic Tuna (ICCAT). UKOT conservation managers would, therefore, be justified in prioritising unilateral leatherback conservation action, and multilateral efforts through the Cartagena convention and regional fishery management mechanisms, over potentially costly accessions to additional MEAs.
Abstract.
Stringell TB, Calosso MC, Claydon JAB, Clerveaux W, Godley BJ, Lockhart KJ, Phillips Q, Ranger S, Richardson PB, Sanghera A, et al (2013). Marine turtle harvest in a mixed small-scale fishery: Evidence for revised management measures.
Ocean and Coastal Management,
82, 34-42.
Abstract:
Marine turtle harvest in a mixed small-scale fishery: Evidence for revised management measures
Small-scale fisheries (SSF) account for around half of the world's marine and inland fisheries, but their impact on the marine environment is usually under-estimated owing to difficulties in monitoring and regulation. Successful management of mixed SSF requires holistic approaches that sustainably exploit target species, consider non-target species and maintain fisher livelihoods. For two years, we studied the marine turtle fishery in the Turks and Caicos Islands (TCI) in the Wider Caribbean Region, where the main export fisheries are queen conch (Strombus gigas) and the spiny lobster (Panulirus argus); with fin-fish, green turtles (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata) taken for domestic consumption. We evaluate the turtle harvest in relation to the other fisheries and recommend legislation and management alternatives. We demonstrate the connectivity between multi-species fisheries and artisanal turtle capture: with increasing lobster catch-per-unit-effort (CPUE), hawksbill catch increased whilst green turtle catch decreased. With increasing conch CPUE, hawksbill catch declined and there was no demonstrable effect on green turtle catch. We estimate 176-324 green and 114-277 hawksbill turtles are harvested annually in TCI: the largest documented legal hawksbill fishery in the western Atlantic. of particular concern is the capture of adult turtles. Current legislation focuses take on larger individuals that are key to population maintenance. Considering these data we recommend the introduction of maximum size limits for both species and a closed season on hawksbill take during the lobster fishing season. Our results highlight the need to manage turtles as part of a broader approach to SSF management. © 2013 Elsevier Ltd.
Abstract.
Wright LI, Fuller WJ, Godley BJ, McGowan A, Tregenza T, Broderick AC (2013). No benefits of polyandry to female green turtles.
Behavioral Ecology,
24(4), 1022-1029.
Abstract:
No benefits of polyandry to female green turtles
Multiple paternity is extremely common in natural populations of almost all reptiles studied to date, suggesting that pay-offs from polyandrous mating systems are important in these taxonomic groups. However, strong evidence in support of direct or indirect benefits to females is scarce. We examined the relationship between polyandry and components of female reproductive success and offspring fitness in the promiscuous green turtle (Chelonia mydas), a species that exhibits highly variable levels of multiple paternity. We did not detect any clear fitness benefits to polyandrous females in this study, and we discuss the potential of sexual conflict to influence female mating patterns in marine turtles. We show that polyandrous females produce significantly smaller clutches than monandrous females, highlighting a potential cost to polyandry in green turtles. Furthermore, multiple paternity was more common in returning females (recorded breeding in a previous season) than in females nesting for the first time at our study site, possibly reflecting increased encounter rates with males or sperm storage across breeding seasons. Our results reveal potentially complex influences of female traits, environment, and mating strategy on components of reproductive success, and we discuss the challenges associated with unraveling the costs and benefits of multiple mating in natural populations. © 2013 the Author. Published by Oxford University Press on behalf of the International Society for Behavioral Ecology. All rights reserved.
Abstract.
Richardson PB, Broderick AC, Coyne MS, Ekanayake L, Kapurusinghe T, Premakumara C, Ranger S, Saman MM, Witt MJ, Godley BJ, et al (2013). Satellite telemetry reveals behavioural plasticity in a green turtle population nesting in Sri Lanka.
Marine Biology,
160(6), 1415-1426.
Abstract:
Satellite telemetry reveals behavioural plasticity in a green turtle population nesting in Sri Lanka
Satellite transmitters were deployed on ten green turtles (Chelonia mydas) nesting in Rekawa Sanctuary (RS-80.851°E 6.045°N), Sri Lanka, during 2006 and 2007 to determine inter-nesting and migratory behaviours and foraging habitats. Nine turtles subsequently nested at RS and demonstrated two inter-nesting strategies linked to the location of their residence sites. Three turtles used local shallow coastal sites within 60 km of RS during some or all of their inter-nesting periods and then returned to and settled at these sites on completion of their breeding seasons. In contrast, five individuals spent inter-nesting periods proximate to RS and then migrated to and settled at distant (>350 km) shallow coastal residence sites. Another turtle also spent inter-nesting periods proximate to RS and then migrated to a distant oceanic atoll and made forays into oceanic waters for 42 days before transmissions ceased. This behavioural plasticity informs conservation management beyond protection at the nesting beach. © 2013 Springer-Verlag Berlin Heidelberg.
Abstract.
Richardson PB, Broderick AC, Coyne MS, Ekanayake L, Kapurusinghe T, Premakumara C, Ranger S, Saman MM, Witt MJ, Godley BJ, et al (2013). Satellite telemetry reveals behavioural plasticity in a green turtle population nesting in Sri Lanka. Marine Biology, 1-12.
Snape RTE, Beton D, Broderick AC, Çiçek BA, Fuller WJ, Özden O, Godley BJ (2013). Strand monitoring and anthropological surveys provide insight into marine turtle bycatch in small-scale fisheries of the Eastern Mediterranean.
Chelonian Conservation and Biology,
12(1), 44-55.
Abstract:
Strand monitoring and anthropological surveys provide insight into marine turtle bycatch in small-scale fisheries of the Eastern Mediterranean
It has become widely recognized that a large gap exists in the global knowledge of fisheries due to the continued oversight of the small-scale sector. For populations of marine turtles restricted to the eastern Mediterranean, bycatch in small-scale fisheries is a concern. By using North Cyprus as a case study for the region, we used anthropological methods to estimate the magnitude of marine turtle bycatch, while presenting novel information on the marine turtle life stages using the coast and profiling the fishery itself. Our analyses suggest that as many as 1000 turtles may be caught annually by this fishery with an estimated mortality rate of 60%. Trammel nets were the main cause of marine turtle bycatch. Strandings coincided with setting of trammel nets that target siganids (Siganus luridus and Siganus rivulatus) and the majority of bycatch registered by fishers were caught in these gear types. We demonstrate a relatively simple approach to evaluating marine turtle bycatch, providing information that will allow local authorities and conservation groups to direct further research and possible mitigation measures. © 2013 Chelonian Research Foundation.
Abstract.
Weber N, Weber SB, Godley BJ, Ellick J, Witt M, Broderick AC (2013). Telemetry as a tool for improving estimates of marine turtle abundance.
Biological Conservation,
167, 90-96.
Abstract:
Telemetry as a tool for improving estimates of marine turtle abundance
Accurate estimates of abundance are fundamental to the conservation of threatened species, but are often difficult to obtain directly. Population size assessments of marine turtles are often based on counts of nests, which are then related to abundance using the mean number of clutches laid by individuals within a season. Due to low re-encounter probabilities, clutch frequency has proven difficult to estimate reliably, particularly for large populations that make a major contribution to global stock assessments. We use a combination of VHF radio-telemetry and Argos-linked Fastloc™ GPS devices to improve clutch frequency estimates for one of the world's largest green turtle rookeries at Ascension Island. Females fitted with VHF tags at the start of the season (. n=. 40) were re-encountered with a probability of 85% and laid a minimum average of 5.8 clutches. Three of these turtles were fitted with VHF and GPS devices and using the data collected by the latter, were found to lay an average of 6.3 clutches. GPS-telemetry detected emergences observed using radio-telemetry, and confirmed that some radio-tagged turtles laid again after their last observed emergence. Correcting for missed nesting events yielded a mean clutch frequency of 6.3, more than doubling the previous estimate of 3.0 for this population. Applying this revised assessment to annual nest counts reduces the estimated size of this population by 52%. Conventional tagging approaches may considerably underestimate annual fecundity of turtles, resulting in inflated population size estimates. We call for urgent reassessment of baseline abundance values for regionally important populations. © 2013 Elsevier Ltd.
Abstract.
2012
Witt MJ, Sheehan EV, Bearhop S, Broderick AC, Conley DC, Cotterell SP, Crow E, Grecian WJ, Halsband C, Hodgson DJ, et al (2012). Assessing wave energy effects on biodiversity: the Wave Hub experience. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 370(1959), 502-529.
Witt MJ, Sheehan EV, Bearhop S, Broderick AC, Conley DC, Cotterell SP, Crow E, Grecian WJ, Halsband C, Hodgson DJ, et al (2012). Assessing wave energy effects on biodiversity: the Wave Hub experience.
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences,
370(1959), 502-529.
Abstract:
Assessing wave energy effects on biodiversity: the Wave Hub experience
Marine renewable energy installations harnessing energy from wind, wave and tidal resources are likely to become a large part of the future energy mix worldwide. The potential to gather energy from waves has recently seen increasing interest, with pilot developments in several nations. Although technology to harness wave energy lags behind that of wind and tidal generation, it has the potential to contribute significantly to energy production. As wave energy technology matures and becomes more widespread, it is likely to result in further transformation of our coastal seas. Such changes are accompanied by uncertainty regarding their impacts on biodiversity. To date, impacts have not been assessed, as wave energy converters have yet to be fully developed. Therefore, there is a pressing need to build a framework of understanding regarding the potential impacts of these technologies, underpinned by methodologies that are transferable and scalable across sites to facilitate formal meta-analysis. We first review the potential positive and negative effects of wave energy generation, and then, with specific reference to our work at the Wave Hub (a wave energy test site in southwest England, UK), we set out the methodological approaches needed to assess possible effects of wave energy on biodiversity. We highlight the need for national and international research clusters to accelerate the implementation of wave energy, within a coherent understanding of potential effects-both positive and negative. © 2011 the Royal Society.
Abstract.
Rees AF, Al-Kiyumi A, Broderick AC, Papathanasopoulou N, Godley BJ (2012). Conservation related insights into the behaviour of the olive ridley sea turtle Lepidochelys olivacea nesting in Oman.
Marine Ecology Progress Series,
450, 195-205.
Abstract:
Conservation related insights into the behaviour of the olive ridley sea turtle Lepidochelys olivacea nesting in Oman
We followed the movements of 9 adult female olive ridley turtles Lepidochelys olivacea after nesting on Masirah Island, Oman, using satellite tracking. Their post-breeding migrations ranged from 85 to 796 km. Three individuals travelled north to foraging grounds in Pakistan, Iran and the United Arab Emirates. The other 6 turtles remained in Omani seas for extended periods (mean ± SD = 171.3 ± 109.4 d; range = 40 to 310 d). These locally resident turtles experienced biannual cooling of sea temperatures due to the effect of the west Arabian Sea upwelling which was not experienced by those that migrated to the north. Indications of disparity in turtle size between foraging locations are identified for the first time in this species. The majority of turtles (8) settled in coastal areas of water depth
Abstract.
Rees AF, Al-Kiyumi A, Broderick AC, Papathanasopoulou N, Godley BJ (2012). Each to their own: Inter-specific differences in migrations of Masirah Island turtles.
Chelonian Conservation and Biology,
11(2), 243-248.
Abstract:
Each to their own: Inter-specific differences in migrations of Masirah Island turtles
We tracked two adult female green turtles (Chelonia mydas) from their nesting location on Masirah Island, Oman (lat 20.441°N, long 58.843°E) into the Red Sea. Comparing these tracks with published movements of nesting loggerhead (Caretta caretta) and olive ridley (Lepidochelys olivacea) turtles, also tracked from Masirah, revealed remarkably different inter-specific patterns of post-nesting dispersal. High-capacity artisanal fisheries, with undescribed levels of sea turtle bycatch, exist within the region, making introduction of effective conservation measures difficult. © 2012 Chelonian Research Foundation.
Abstract.
Scott R, Hodgson DJ, Witt MJ, Coyne MS, Blumenthal JM, Broderick AC, Richardson PB, Rees AF, Godley BJ, Coyne MS, et al (2012). Global analysis of satellite tracking data shows that adult green turtles are significantly aggregated in Marine Protected Areas.
Global Ecology and BiogeographyAbstract:
Global analysis of satellite tracking data shows that adult green turtles are significantly aggregated in Marine Protected Areas
Aim Tracking technologies are often proposed as a method to elucidate the complex migratory life histories of migratory marine vertebrates, allowing spatially explicit threats to be identified and mitigated. We conducted a global analysis of foraging areas of adult green turtles (Chelonia mydas) subject to satellite tracking (n= 145) and the conservation designation of these areas according to International Union for Conservation of Nature criteria. Location the green turtle has a largely circumtropical distribution, with adults migrating up to thousands of kilometres between nesting beaches and foraging areas, typically in neritic seagrass or algal beds. Methods We undertook an assessment of satellite tracking projects that followed the movements of green turtles in tropical and subtropical habitats. This approach was facilitated by the use of the Satellite Tracking and Analysis Tool () and the integration of publicly available data on Marine Protected Areas (MPAs). Results We show that turtles aggregate in designated MPAs far more than would be expected by chance when considered globally (35% of all turtles were located within MPAs) or separately by ocean basin (Atlantic 67%, Indian 34%, Mediterranean 19%, Pacific 16%). Furthermore, we show that the size, level of protection and time of establishment of MPAs affects the likelihood of MPAs containing foraging turtles, highlighting the importance of large, well-established reserves. Main conclusions Our findings constitute compelling evidence of the world-wide effectiveness of extant MPAs in circumscribing important foraging habitats for a marine megavertebrate. © 2012 Blackwell Publishing Ltd.
Abstract.
Scott R, Hodgson DJ, Witt MJ, Coyne MS, Adnyana W, Blumenthal JM, Broderick AC, Canbolat AF, Catry P, Ciccione S, et al (2012). Global analysis of satellite tracking data shows that adult green turtles are significantly aggregated in Marine Protected Areas.
Global Ecology and Biogeography,
21(11), 1053-1061.
Abstract:
Global analysis of satellite tracking data shows that adult green turtles are significantly aggregated in Marine Protected Areas
Aim Tracking technologies are often proposed as a method to elucidate the complex migratory life histories of migratory marine vertebrates, allowing spatially explicit threats to be identified and mitigated. We conducted a global analysis of foraging areas of adult green turtles (Chelonia mydas) subject to satellite tracking (n= 145) and the conservation designation of these areas according to International Union for Conservation of Nature criteria. Location the green turtle has a largely circumtropical distribution, with adults migrating up to thousands of kilometres between nesting beaches and foraging areas, typically in neritic seagrass or algal beds. Methods We undertook an assessment of satellite tracking projects that followed the movements of green turtles in tropical and subtropical habitats. This approach was facilitated by the use of the Satellite Tracking and Analysis Tool (http://www.seaturtle.org) and the integration of publicly available data on Marine Protected Areas (MPAs). Results We show that turtles aggregate in designated MPAs far more than would be expected by chance when considered globally (35% of all turtles were located within MPAs) or separately by ocean basin (Atlantic 67%, Indian 34%, Mediterranean 19%, Pacific 16%). Furthermore, we show that the size, level of protection and time of establishment of MPAs affects the likelihood of MPAs containing foraging turtles, highlighting the importance of large, well-established reserves. Main conclusions Our findings constitute compelling evidence of the world-wide effectiveness of extant MPAs in circumscribing important foraging habitats for a marine megavertebrate. © 2012 Blackwell Publishing Ltd.
Abstract.
Richardson PB, Broderick AC, Coyne MS, Gore S, Gumbs JC, Pickering A, Ranger S, Witt MJ, Godley BJ (2012). Leatherback turtle conservation in the Caribbean UK overseas territories: Act local, think global?. Marine Policy
Casale P, Broderick AC, Freggi D, Mencacci R, Fuller WJ, Godley BJ, Luschi P (2012). Long-term residence of juvenile loggerhead turtles to foraging grounds: a potential conservation hotspot in the Mediterranean. Aquatic Conservation: Marine and Freshwater Ecosystems
Casale P, Broderick AC, Freggi D, Mencacci R, Fuller WJ, Godley BJ, Luschi P (2012). Long-term residence of juvenile loggerhead turtles to foraging grounds: a potential conservation hotspot in the Mediterranean.
Aquatic Conservation: Marine and Freshwater Ecosystems,
22(2), 144-154.
Abstract:
Long-term residence of juvenile loggerhead turtles to foraging grounds: a potential conservation hotspot in the Mediterranean
Identifying highly frequented areas is a priority for sea turtle conservation. Although juveniles represent the bulk of the population, a minority of studies have investigated their movement patterns. Six large juvenile loggerhead turtles that were found and released in an important foraging ground in the Mediterranean, the Tunisian continental shelf were tracked. Tracking data were obtained via satellite for periods ranging from 120 to 225days and allowed the identification of high use areas. All turtles generally performed apparently non-directed, wandering movements in waters with a wide range of seafloor depths. They showed clear residential behaviour to the region with no evident seasonal pattern. Core areas of residence were in the neritic zone or on the edge of the continental shelf, largely overlapping among individuals, and were much smaller than residential oceanic areas reported elsewhere. When integrated into current knowledge, these results suggest an ecological-behavioural model of a gradual shift from a pelagic-vagile to a benthic-sedentary life style with progressive reduction of home ranges. They also highlight an area of the continental shelf and offshore waters as potential core foraging ground for large juvenile loggerhead turtles in the Mediterranean informing future spatial management for loggerhead turtles. © 2012 John Wiley & Sons, Ltd.
Abstract.
Leeney RH, Witt MJ, Broderick AC, Buchanan J, Jarvis DS, Richardson PB, Godley BJ (2012). Marine megavertebrates of Cornwall and the Isles of Scilly: Relative abundance and distribution.
Journal of the Marine Biological Association of the United Kingdom,
92(8), 1823-1833.
Abstract:
Marine megavertebrates of Cornwall and the Isles of Scilly: Relative abundance and distribution
We document patterns of distribution and relative abundance of marine megavertebrate fauna around Cornwall and the Isles of Scilly from a combination of aerial and boat-based surveying. Between January 2006 and November 2007, 20 aerial surveys were undertaken, comprising over 40 hours of on-effort flying time. In April to October of these years, 27 effort-corrected ferry surveys were also conducted from a passenger ferry travelling between Cornwall and the Isles of Scilly. Opportunistic sightings were also logged by the crew members of the ferry and another vessel travelling regularly along the same route on 155 days. Ten megavertebrate species were sighted: basking sharks Cetorhinus maximus, sunfish Mola mola, common dolphins Delphinus delphis, harbour porpoise Phocoena phocoena, grey seals Halichoerus grypus, Risso's dolphins Grampus griseus, bottlenose dolphins Tursiops truncatus, minke whales Balaenoptera acutorostrata, long-finned pilot whales Globicephala melas and killer whale Orcinus orca. During aerial surveys, 206 sighting events of seven species were made, compared with 145 sighting events of eight species during ferry surveys and 293 sighting events of 10 species from opportunistic ship-board data collection efforts. Seasonal and spatial patterns in species occurrence were evident. Basking sharks were the most commonly-sighted species in the region and were relatively abundant throughout the estimated 5 km-wide strip of coastal waters covered by the aerial surveys, during spring and summer. Ferry surveys and opportunistic vessel-based sightings data confirmed that the distribution of surface-feeding aggregations of this species was largely around the coasts. Despite the limited scope of this study, it has provided valuable baseline data, and possible insights into the marine biodiversity of the region. © 2012 Marine Biological Association of the United Kingdom.
Abstract.
Hawkes LA, Tomás J, Revuelta O, León YM, Blumenthal JM, Broderick AC, Fish M, Raga JA, Witt MJ, Godley BJ, et al (2012). Migratory patterns in hawksbill turtles described by satellite tracking.
Marine Ecology Progress Series,
461, 223-232.
Abstract:
Migratory patterns in hawksbill turtles described by satellite tracking
The advent of telemetry has improved knowledge of the spatio-temporal distribution of marine species of conservation concern. Among the sea turtles, the movements of the hawksbill turtle Eretmochelys imbricata are among the least well described. We tracked 10 adult female hawksbill turtles by satellite after nesting in the Dominican Republic (DR) and describe a dichotomy in patterns of movement: some (n = 2) turtles remained in the DR, while others migrated to waters off Honduras and Nicaragua (n = 5) and the Bahamas (n = 1). Transmitters on 2 turtles failed during migration, before they reached their final foraging grounds. We present results from long tracking durations for 3 turtles, including 3 entire remigration intervals, high-lighting foraging ground and nest-site fidelity. Threats to hawksbill turtles are not well documented for Nicaragua or neighbouring Honduras and represent a major information gap. We suggest that directing conservation efforts to regionally important foraging areas, such as those in Nicaragua, and strengthening national conservation in each nation with significant hawksbill nesting offers a clear way forward for the conservation of hawksbill turtles in the region. © Inter-Research 2012 · www.int-res.com.
Abstract.
Wright LI, Fuller WJ, Godley BJ, McGowan A, Tregenza T, Broderick AC (2012). Reconstruction of paternal genotypes over multiple breeding seasons reveals male green turtles do not breed annually.
Molecular Ecology,
21(14), 3625-3635.
Abstract:
Reconstruction of paternal genotypes over multiple breeding seasons reveals male green turtles do not breed annually
For species of conservation concern, knowledge of key life-history and demographic components, such as the number and sex ratio of breeding adults, is essential for accurate assessments of population viability. Species with temperature-dependent sex determination can produce heavily biased primary sex ratios, and there is concern that adult sex ratios may be similarly skewed or will become so as a result of climate warming. Prediction and mitigation of such impacts are difficult when life-history information is lacking. In marine turtles, owing to the difficultly in observing males at sea, the breeding interval of males is unknown. It has been suggested that male breeding periodicity may be shorter than that of females, which could help to compensate for generally female-biased sex ratios. Here we outline how the use of molecular-based paternity analysis has allowed us, for the first time, to assess the breeding interval of male marine turtles across multiple breeding seasons. In our study rookery of green turtles (Chelonia mydas), 97% of males were assigned offspring in only one breeding season within the 3-year study period, strongly suggesting that male breeding intervals are frequently longer than 1 year at this site. Our results also reveal a sex ratio of breeding adults of at least 1.3 males to each female. This study illustrates the utility of molecular-based parentage inference using reconstruction of parental genotypes as a method for monitoring the number and sex ratio of breeders in species where direct observations or capture are difficult. © 2012 Blackwell Publishing Ltd.
Abstract.
Wright LI, Fuller WJ, Godley BJ, McGowan A, Tregenza T, Broderick AC (2012). Reconstruction of paternal genotypes over multiple breeding seasons reveals male green turtles do not breed annually.
Mol Ecol,
21(14), 3625-3635.
Abstract:
Reconstruction of paternal genotypes over multiple breeding seasons reveals male green turtles do not breed annually.
For species of conservation concern, knowledge of key life-history and demographic components, such as the number and sex ratio of breeding adults, is essential for accurate assessments of population viability. Species with temperature-dependent sex determination can produce heavily biased primary sex ratios, and there is concern that adult sex ratios may be similarly skewed or will become so as a result of climate warming. Prediction and mitigation of such impacts are difficult when life-history information is lacking. In marine turtles, owing to the difficultly in observing males at sea, the breeding interval of males is unknown. It has been suggested that male breeding periodicity may be shorter than that of females, which could help to compensate for generally female-biased sex ratios. Here we outline how the use of molecular-based paternity analysis has allowed us, for the first time, to assess the breeding interval of male marine turtles across multiple breeding seasons. In our study rookery of green turtles (Chelonia mydas), 97% of males were assigned offspring in only one breeding season within the 3-year study period, strongly suggesting that male breeding intervals are frequently longer than 1year at this site. Our results also reveal a sex ratio of breeding adults of at least 1.3 males to each female. This study illustrates the utility of molecular-based parentage inference using reconstruction of parental genotypes as a method for monitoring the number and sex ratio of breeders in species where direct observations or capture are difficult.
Abstract.
Author URL.
Wright LI, Stokes KL, Fuller WJ, Godley BJ, McGowan A, Snape R, Tregenza T, Broderick AC (2012). Turtle mating patterns buffer against disruptive effects of climate change.
Proc Biol Sci,
279(1736), 2122-2127.
Abstract:
Turtle mating patterns buffer against disruptive effects of climate change.
For organisms with temperature-dependent sex determination (TSD), skewed offspring sex ratios are common. However, climate warming poses the unique threat of producing extreme sex ratio biases that could ultimately lead to population extinctions. In marine turtles, highly female-skewed hatchling sex ratios already occur and predicted increases in global temperatures are expected to exacerbate this trend, unless species can adapt. However, it is not known whether offspring sex ratios persist into adulthood, or whether variation in male mating success intensifies the impact of a shortage of males on effective population size. Here, we use parentage analysis to show that in a rookery of the endangered green turtle (Chelonia mydas), despite an offspring sex ratio of 95 per cent females, there were at least 1.4 reproductive males to every breeding female. Our results suggest that male reproductive intervals may be shorter than the 2-4 years typical for females, and/or that males move between aggregations of receptive females, an inference supported by our satellite tracking, which shows that male turtles may visit multiple rookeries. We suggest that male mating patterns have the potential to buffer the disruptive effects of climate change on marine turtle populations, many of which are already seriously threatened.
Abstract.
Author URL.
2011
Shuter JL, Broderick AC, Agnew DJ, Jonzen N, Godley BJ, Milner-Gulland EJ, Thirgood S (2011). Conservation and management of migratory species. In Milner-Gulland EJ, Fryxell JM, Sinclair ARE (Eds.)
Animal Migration, Oxford Univ Pr.
Abstract:
Conservation and management of migratory species
Abstract.
Weber SB, Broderick AC, Groothuis TGG, Ellick J, Godley BJ, Blount JD (2011). Fine-scale thermal adaptation in a green turtle nesting population.
Proceedings of the Royal Society of London B: Biological SciencesAbstract:
Fine-scale thermal adaptation in a green turtle nesting population
The effect of climate warming on the reproductive success of ectothermic animals is currently a subject of major conservation concern. However, for many threatened species we still know surprisingly little about the extent of naturally-occurring adaptive variation in heat tolerance. Here, we show that the thermal tolerances of green turtle (Chelonia mydas) embryos in a single, island-breeding population have diverged in response to the contrasting incubation temperatures of nesting beaches just a few kilometres apart. In natural nests and in a common-garden rearing experiment, the offspring of females nesting on a naturally hot (black sand) beach survived better and grew larger at hot incubation temperatures compared to the offspring of females nesting on a cooler (pale sand) beach nearby. These differences were due to shallower thermal reaction norms in the hot beach population, rather than a shift in thermal optima, and were not related to maternal provisioning of resources into eggs. Our results suggest that marine turtle nesting behaviour can drive adaptive differentiation at surprisingly fine spatial scales, and have important implications for how we define conservation units for protection. In particular, previous studies may have underestimated the extent of adaptive structuring in marine turtle populations which may significantly affect their capacity to respond to environmental change.
Abstract.
Hawkes LA, Witt MJ, Broderick AC, Coker JW, Coyne MS, Dodd M, Frick MG, Godfrey MH, Griffin DB, Murphy SR, et al (2011). Home on the range: Spatial ecology of loggerhead turtles in Atlantic waters of the USA.
Diversity and Distributions,
17(4), 624-640.
Abstract:
Home on the range: Spatial ecology of loggerhead turtles in Atlantic waters of the USA
Aim Although satellite tracking has yielded much information regarding the migrations and habitat use of threatened marine species, relatively little has been published about the environmental niche for loggerhead sea turtles Caretta caretta in north-west Atlantic waters. Location North Carolina, South Carolina and Georgia, USA. Methods We tracked 68 adult female turtles between 1998 and 2008, one of the largest sample sizes to date, for 372.2±210.4days (mean±SD). Results We identified two strategies: (1) 'seasonal' migrations between summer and winter coastal areas (n=47), although some turtles made oceanic excursions (n=4) and (2) occupation of more southerly 'year-round' ranges (n=18). Seasonal turtles occupied summer home ranges of 645.1km2 (median, n = 42; using α-hulls) predominantly north of 35° latitude and winter home ranges of 339.0km2 (n=24) in a relatively small area on the narrow shelf off North Carolina. We tracked some of these turtles through successive summer (n=8) and winter (n=3) seasons, showing inter-annual home range repeatability to within 14.5km of summer areas and 10.3km of winter areas. For year-round turtles, home ranges were 1889.9km2. Turtles should be tracked for at least 80days to reliably estimate the home range size in seasonal habitats. The equivalent minimum duration for 'year-round' turtles is more complex to derive. We define an environmental envelope of the distribution of North American loggerhead turtles: warm waters (between 18.2 and 29.2°C) on the coastal shelf (in depths of 3.0-89.0m). Main conclusions Our findings show that adult female loggerhead turtles show predictable, repeatable home range behaviour and do not generally leave waters of the USA, nor the continental shelf (
Abstract.
Weber SB, Blount JD, Godley BJ, Witt MJ, Broderick AC (2011). Rate of egg maturation in marine turtles exhibits 'universal temperature dependence'.
J Anim Ecol,
80(5), 1034-1041.
Abstract:
Rate of egg maturation in marine turtles exhibits 'universal temperature dependence'.
1. The metabolic theory of ecology (MTE) predicts that, after correcting for body mass variation among organisms, the rates of most biological processes will vary as a universal function of temperature. However, empirical support for 'universal temperature dependence' (UTD) is currently equivocal and based on studies of a limited number of traits. 2. In many ectothermic animals, the rate at which females produce mature eggs is temperature dependent and may be an important factor in determining the costs of reproduction. 3. We tested whether the rate of egg maturation in marine turtles varies with environmental temperature as predicted by MTE, using the time separating successive clutches of individual females to estimate the rate at which eggs are formed. We also assessed the phenotypic contribution to this rate, by using radio telemetry to make repeated measurements of interclutch intervals for individual green turtles (Chelonia mydas). 4. Rates of egg maturation increased with seasonally increasing water temperatures in radio-tracked green turtles, but were not repeatable for individual females, and did not vary according to maternal body size or reproductive investment (number and size of eggs produced). 5. Using a collated data set from several different populations and species of marine turtles, we then show that a single relationship with water temperature explains most of the variation in egg maturation rates, with a slope that is statistically indistinguishable from the UTD predicted by MTE. However, several alternative statistical models also described the relationship between temperature and egg maturation rates equally parsimoniously. 6. Our results offer novel support for the MTE's predicted UTD of biological rates, although the underlying mechanisms require further study. The strong temperature dependence of egg maturation combined with the apparently weak phenotypic contribution to this rate has interesting behavioural implications in ectothermic animals. We suggest that maternal thermoregulatory behaviour in marine turtles, and many other reptiles, is consistent with a strategy of adaptively increasing body temperatures to accelerate egg maturation.
Abstract.
Author URL.
Witt MJ, Godley BJ, Broderick AC, Coyne MS (2011). Tracking leatherback turtles from the world's largest rookery: assessing threats across the South Atlantic.
Proceedings of the Royal Society BAbstract:
Tracking leatherback turtles from the world's largest rookery: assessing threats across the South Atlantic
Despite extensive work carried out on leatherback turtles (Dermochelys coriacea) in the North Atlantic and Indo-Pacific, very little is known of the at-sea distribution of this species in the South Atlantic, where the world's largest population nests in Gabon (central Africa). This paucity of data is of marked concern given the pace of industrialization in fisheries with demonstrable marine turtle bycatch in African/Latin American waters. We tracked the movements of 25 adult female leatherback turtles obtaining a range of fundamental and applied insights, including indications for methodological advancement. Individuals could be assigned to one of three dispersal strategies, moving to (i) habitats of the equatorial Atlantic, (ii) temperate habitats off South America or (iii) temperate habitats off southern Africa. While occupying regions with high surface chlorophyll concentrations, these strategies exposed turtles to some of the world's highest levels of longline fishing effort, in addition to areas with coastal gillnet fisheries. Satellite tracking highlighted that at least 11 nations should be involved in the conservation of this species in addition to those with distant fishing fleets. The majority of tracking days were, however, spent in the high seas, where effective implementation of conservation efforts is complex to achieve.
Abstract.
Humber F, Godley BJ, Ramahery V, Broderick AC (2011). Using community members to assess artisanal fisheries: the marine turtle fishery in Madagascar. Animal Conservation(14), 175-185.
2010
Leeney RH, Broderick AC, Mills C, Sayer S, Witt MJ, Godley BJ (2010). Abundance, distribution and haul-out behaviour of grey seals (Halichoerus grypus) in Cornwall and the Isles of Scilly, UK.
Journal of the Marine Biological Association of the United Kingdom,
90(5), 1033-1040.
Abstract:
Abundance, distribution and haul-out behaviour of grey seals (Halichoerus grypus) in Cornwall and the Isles of Scilly, UK
This study investigated the phenology, patterns of haul-out habitat use and distribution of the grey seal around Cornwall and the Isles of Scilly. A full census of the coast was carried out by boat over 4 days, in order to make a full count of seals hauled out and close to the coast, and to document all haul-out sites. Regular land-based surveys were made of three haul-out sites in Cornwall, to investigate the effects of spatial, temporal and environmental factors on seal haul-out behaviour. Data from 2004 to 2007 were analysed to describe long-term temporal variation in seal abundance at two haul-out sites. A total of 592 sightings were made along the coast of Cornwall and the Isles of Scilly over the four-day census period; 476 of these sightings (80.4%) were recorded at six main haul-out sites. The highest proportion of seals was observed at three haul-out areas on the Isles of Scilly. In Cornwall, seals were observed in higher numbers on the north coast, where the three largest mainland haul-out sites were documented, than on the south coast. At one key haul-out site in Cornwall, a distinct seasonal pattern was evident in data collected between 2004 and 2007, with higher numbers of seals present during the moulting and breeding seasons than over the summer months. There was considerable inter-annual variability in peak seal abundance, during the moulting season, at this site. There was no significant variation in haul-out behaviour with tidal state at this site, although haul-out counts were generally highest at mid-ebb tides. Data on seal abundance, distribution and haul-out behaviour may aid the designation of Special Areas of Conservation for the protection of grey seals in Cornwall and the Isles of Scilly. © 2010 Marine Biological Association of the United Kingdom.
Abstract.
Witt MJ, Åkesson S, Broderick AC, Coyne MS, Ellick J, Formia A, Hays GC, Luschi P, Stroud S, Godley BJ, et al (2010). Assessing accuracy and utility of satellite-tracking data using Argos-linked Fastloc-GPS. Animal Behaviour, 80(3), 571-581.
Rees AF, Al Saady S, Broderick AC, Coyne MS, Papathanasopoulou N, Godley BJ (2010). Behavioural polymorphism in one of the world's largest populations of loggerhead sea turtles Caretta caretta.
Marine Ecology Progress Series,
418, 201-212.
Abstract:
Behavioural polymorphism in one of the world's largest populations of loggerhead sea turtles Caretta caretta
To aid management and conservation of widely distributed marine vertebrate species, it is necessary to have a knowledge and understanding of their spatial ecology. We tracked 10 adult female loggerhead turtles Caretta caretta from Masirah Island, Sultanate of Oman, which hosts one of the world's largest breeding aggregations. Transmitters were specifically deployed early in the nesting season to enable tracking throughout the internesting and post-nesting habitats. Turtles displayed a dichotomy in behaviour during the internesting period, with 6 remaining close to Masirah Island and the others undertaking circuitous oceanic loops, hundreds of kilometres in length. This behaviour did not appear to be related to body size. Tracking-derived minimum clutch frequency was on average (± SD) 4.8 ±1.2 nests (n = 8 ind.). Post-nesting migrations revealed a propensity towards long-term utilisation of oceanic habitats in the region between Socotra Island (Yemen) and the mainland of Yemen/Oman, with 76 ± 15.4% of time spent in oceanic habitat (n = 8 ind.). The spatial footprint of our tracked turtles was found to be far less than that of a similar number of turtles that were tagged later in the same season (from a separate unpublished study) and from long-distance returns of flipper tags. The spatial and temporal sub-structuring of the population highlights the need for more comprehensive tracking projects, with deployments across the breeding season in multiple years, in order to obtain reliable estimations of high-use foraging habitats of widely dispersed marine vertebrates. Variation in behaviour patterns suggests the need for diverse conservation measures. © Inter-Research 2010.
Abstract.
Hamann M, Godfrey MH, Seminoff JA, Arthur K, Barata PCR, Bjorndal KA, Bolten AB, Broderick AC, Campbell LM, Carreras C, et al (2010). Global research priorities for sea turtles: Informing management and conservation in the 21st century.
Endangered Species Research,
11(3), 245-269.
Abstract:
Global research priorities for sea turtles: Informing management and conservation in the 21st century
Over the past 3 decades, the status of sea turtles and the need for their protection to aid population recovery have increasingly captured the interest of government agencies, non-governmental organisations (NGOs) and the general public worldwide. This interest has been matched by increased research attention, focusing on a wide variety of topics relating to sea turtle biology and ecology, together with the interrelations of sea turtles with the physical and natural environments. Although sea turtles have been better studied than most other marine fauna, management actions and their evaluation are often hindered by the lack of data on turtle biology, human-turtle interactions, turtle population status and threats. In an effort to inform effective sea turtle conservation a list of priority research questions was assembled based on the opinions of 35 sea turtle researchers from 13 nations working in fields related to turtle biology and/or conservation. The combined experience of the contributing researchers spanned the globe as well as many relevant disciplines involved in conservation research. An initial list of more than 200 questions gathered from respondents was condensed into 20 metaquestions and classified under 5 categories: reproductive biology, biogeography, population ecology, threats and conservation strategies. © Inter-Research 2010.
Abstract.
Witt MJ, McGowan A, Blumenthal JM, Broderick AC, Gore S, Wheatley D, White J, Godley BJ (2010). Inferring vertical and horizontal movements of juvenile marine turtles from time-depth recorders.
AQUATIC BIOLOGY,
8(2), 169-177.
Author URL.
Bell CD, Blumenthal JM, Broderick AC, Godley BJ (2010). Investigating potential for depensation in marine turtles: How low can you Go?: Contributed paper.
Conservation Biology,
24(1), 226-235.
Abstract:
Investigating potential for depensation in marine turtles: How low can you Go?: Contributed paper
Where mechanisms inherent within the biology of a species affect individual fitness at low density, demographic-scale depensation may occur, hastening further decline and leading ultimately to population extirpation and species extinction. Reduction in fertility at low population densities has been identified in marine and terrestrial species. Using data on hatch success and hatchling-emergence success as proxies for fertilization success, we conducted a global meta-analysis of data from breeding aggregations of green turtles (Chelonia mydas) and loggerhead turtles (Caretta caretta). We found that there has been no reduction in fertility in small nesting aggregations in either of these species worldwide. We considered mechanisms within the mating strategies and reproductive biology of marine turtles that may allow for novel genetic input and facilitate enhanced gene flow among rookeries. Behavioral reproductive mechanisms, such as natal philopatry and polyandry, may mitigate potential impacts of depensation and contribute to the resilience of these species. © 2009 Society for Conservation Biology.
Abstract.
Bell CD, Blumenthal JM, Broderick AC, Godley BJ (2010). Investigating potential for depensation in marine turtles: how low can you go?.
Conserv Biol,
24(1), 226-235.
Abstract:
Investigating potential for depensation in marine turtles: how low can you go?
Where mechanisms inherent within the biology of a species affect individual fitness at low density, demographic-scale depensation may occur, hastening further decline and leading ultimately to population extirpation and species extinction. Reduction in fertility at low population densities has been identified in marine and terrestrial species. Using data on hatch success and hatchling-emergence success as proxies for fertilization success, we conducted a global meta-analysis of data from breeding aggregations of green turtles (Chelonia mydas) and loggerhead turtles (Caretta caretta). We found that there has been no reduction in fertility in small nesting aggregations in either of these species worldwide. We considered mechanisms within the mating strategies and reproductive biology of marine turtles that may allow for novel genetic input and facilitate enhanced gene flow among rookeries. Behavioral reproductive mechanisms, such as natal philopatry and polyandry, may mitigate potential impacts of depensation and contribute to the resilience of these species.
Abstract.
Author URL.
Blumenthal JM, Austin TJ, Bothwell JB, Broderick AC, Ebanks-Petrie G, Olynik JR, Orr MF, Solomon JL, Witt MJ, Godley BJ, et al (2010). Life in (and out of) the lagoon: Fine-scale movements of green turtles tracked using time-depth recorders.
Aquatic Biology,
9(2), 113-121.
Abstract:
Life in (and out of) the lagoon: Fine-scale movements of green turtles tracked using time-depth recorders
Tracking fine-scale movements in relation to threats is fundamental to the management of exploited marine species, yet there is considerable difficulty associated with gathering such data at sea. By combining a capture-recapture study with deployment of time-depth recorders (TDRs) and ultrasonic tags, we elucidated distribution and daily movements of juvenile green turtles Chelonia mydas exposed to a legal marine turtle fishery in the Cayman Islands. For instrumented turtles, distinct diel activity patterns were observed: dives during the day were shorter and more active than those at night, implying diurnal foraging and nocturnal resting. Spatially, while capture and recapture locations suggested fidelity to a shallow lagoon, when turtles were fitted with TDRs and ultra-sonic tags we demonstrated that they regularly moved out of the lagoon and onto the reef, where they could legally be captured in the marine turtle fishery. Our results are thus novel and valuable in a management context in that we demonstrated that seemingly protected aggregations of juvenile green turtles within a lagoon were, in fact, exposed to legal capture on a near-daily basis. This emphasizes the importance of assessing diel activity patterns of juvenile marine turtles, particularly with respect to directed take and other threats. © Inter-Research 2010.
Abstract.
Fuller WJ, Broderick AC, Enever R, Thorne P, Godley BJ (2010). Motile homes: a comparison of the spatial distribution of epibiont communities on Mediterranean sea turtles.
Journal of Natural History,
44(27), 1743-1753.
Abstract:
Motile homes: a comparison of the spatial distribution of epibiont communities on Mediterranean sea turtles
Understanding the ecological roles performed by an individual species requires knowledge from a wide range of disciplines; here we analyze the epibiont-host relationship found in marine turtles. During the study we recorded five new species of sea turtle epibiont: Laomedea flexuosa, Caprella fretensis, Hyale nilssoni, Hyale schmidti, Parasinelobus chevreuxi; as part of a total of nine zoological epibionts present on 35 female green turtles (Chelonia mydas) and 100 loggerhead turtles (Caretta caretta) nesting in Cyprus. The two most commonly occurring epibionts were acorn barnacles Chelonibia testudinaria and Chelonibia caretta, with larger specimens of both species recorded on loggerhead turtles. We analyzed the spatial distribution of these two barnacle species upon the carapaces of their hosts. Specimens of C. testudinaria situated on the anterior half of the carapace were larger than those located at the posterior. A significantly larger proportion of loggerhead turtles (152.5%) hosted epibionts in comparison to green turtles (30.3%). All non-barnacle epibionts were associated with either posterior algal mats or carapace scars. © 2010 Taylor & Francis.
Abstract.
Fuller WJ, Broderick AC, Enever R, Thorne P, Godley BJ (2010). Motile homes: a comparison of the spatial distribution of epibiont communities on Mediterranean sea turtles.
JOURNAL OF NATURAL HISTORY,
44(27-28), 1743-1753.
Author URL.
Witt MJ, Hawkes LA, Godfrey MH, Godley BJ, Broderick AC (2010). Predicting the impacts of climate change on a globally distributed species: the case of the loggerhead turtle.
J Exp Biol,
213(6), 901-911.
Abstract:
Predicting the impacts of climate change on a globally distributed species: the case of the loggerhead turtle.
Marine turtles utilise terrestrial and marine habitats and several aspects of their life history are tied to environmental features that are altering due to rapid climate change. We overview the likely impacts of climate change on the biology of these species, which are likely centred upon the thermal ecology of this taxonomic group. Then, focusing in detail on three decades of research on the loggerhead turtle (Caretta caretta L.), we describe how much progress has been made to date and how future experimental and ecological focus should be directed. Key questions include: what are the current hatchling sex ratios from which to measure future climate-induced changes? What are wild adult sex ratios and how many males are necessary to maintain a fertile and productive population? How will climate change affect turtles in terms of their distribution?
Abstract.
Author URL.
Hartnoll RG, Broderick AC, Godley BJ, Musick S, Pearson M, Stroud SA, Saunders KE (2010). Reproduction in the land crab Johngarthia lagostoma on Ascension Island.
Journal of Crustacean Biology,
30(1), 83-92.
Abstract:
Reproduction in the land crab Johngarthia lagostoma on Ascension Island
Reproduction was studied in the land crab Johngarthia lagostoma on Ascension Island in the central South Atlantic from 2005 to 2008. Both sexes are mature by 60-70 mm carapace width (the sample > 4,000 crabs consisted almost entirely of mature specimens). Breeding occurs around the east and south shores of the island, but was studied predominantly at the only easily accessible site at North East Bay. The annual breeding migration extends from January to May, with peak migration in March in most years. The intensity of migration varies between years, and is not obviously related to rainfall. There is lunar entrainment, with increased numbers at the shore in the first quarter, but largest numbers in the last quarter. Both males and females migrate, but with females in greater numbers. At the shore 80 of the crabs are females. A few females mate and lay eggs in the upland residential areas, a greater number do so on the migration route, but the majority only after reaching the shore. Reproductive investment per brood averaged 5% on a dry weight basis, and fecundity averaged 72,000 eggs. © 2010 the Crustacean Society.
Abstract.
Godley BJ, Barbosa C, Bruford M, Broderick AC, Catry P, Coyne MS, Formia A, Hays GC, Witt MJ (2010). Unravelling migratory connectivity in marine turtles using multiple methods.
Journal of Applied Ecology,
47(4), 769-778.
Abstract:
Unravelling migratory connectivity in marine turtles using multiple methods
Comprehensive knowledge of the fundamental spatial ecology of marine species is critical to allow the identification of key habitats and the likely sources of anthropogenic threats, thus informing effective conservation strategies. Research on migratory marine vertebrates has lagged behind many similar terrestrial animal groups, but studies using electronic tagging systems and molecular techniques offer great insights. Marine turtles have complex life history patterns, spanning wide spatio-temporal scales. As a result of this multidimensional complexity, and despite extensive effort, there are no populations for which a truly holistic understanding of the spatial aspects of the life history has been attained. There is a particular lack of information regarding the distribution and habitats utilized during the first few years of life. We used satellite tracking technology to track individual turtles following nesting at the green turtle Chelonia mydas nesting colony at Poilão Island, Guinea Bissau; the largest breeding aggregation in the eastern Atlantic. We further contextualize these data with pan-Atlantic molecular data and oceanographic current modelling to gain insights into likely dispersal patterns of hatchlings and small pelagic juveniles. All adult turtles remained in the waters of West Africa, with strong connectivity demonstrated with Banc D'Arguin, Mauritania. Despite shortcomings in current molecular markers, we demonstrate evidence for profound sub-structuring of marine turtle stocks across the Atlantic; with a high likelihood based on oceanographic modelling that most turtles from Guinea-Bissau are found in the eastern Atlantic. Synthesis and applications. There is an increased need for a better understanding of spatial distribution of marine vertebrates demonstrating life histories with spatio-temporal complexity. We propose the synergistic use of the technologies and modelling used here as a working framework for the future rapid elucidation of the range and likely key habitats used by the different life stages from such species. © 2010 the Authors. Journal compilation © 2010 British Ecological Society.
Abstract.
2009
Witt MJ, Baert B, Broderick AC, Formia A, Fretey J, Gibudi A, Mounguengui GAM, Moussounda C, Ngouessono S, Parnell RJ, et al (2009). Aerial surveying of the world's largest leatherback turtle rookery: a more effective methodology for large-scale monitoring.
Biological Conservation,
142(8), 1719-1727.
Abstract:
Aerial surveying of the world's largest leatherback turtle rookery: a more effective methodology for large-scale monitoring
For many marine megavertebrate species it is challenging to derive population estimates and knowledge on habitat use needed to inform conservation planning. For marine turtles, the logistics required to undertake comprehensive ground-based censuses, across wide spatial and temporal scales, are often insurmountable. This frequently leads to an approach where a limited number of index nesting beaches are monitored in great detail by foot. In this study we use nationwide aerial surveying interfaced with ground assessments across three seasons of leatherback turtle nesting in Gabon (Equatorial West Africa), highlighting the importance of a synoptic approach to marine turtle monitoring. These surveys allow the first complete population assessment of this nesting aggregation to be made, identifying it as the world's largest for the species (36,185-126,480 clutches, approximating to 5865-20,499 breeding females per annum and a total estimate of 15,730 to 41,373 breeding females). Our approach also serendipitously provides insights into the spatial appropriateness of Gabon's protected areas network, for example (mean ± 1SD) 79 ± 6% (range 67-86%) of leatherback turtle activities recorded during aerial surveys (n = 8) occurred within protected areas (345 km, 58%, of surveyed coastline). We identify and discuss sources of potential error in estimating total nesting effort from aerial surveying techniques and show that interannual variation in nesting is considerable, which has implications for the detection of statistically significant changes in population size. Despite its relative costliness per day, aerial surveying can play an important role in providing estimates of relative population abundance of large vertebrates dispersed over extensive areas. Furthermore, it can provide data on habitat use and deliver real-time information on the spatial efficacy of protected area networks. © 2009 Elsevier Ltd. All rights reserved.
Abstract.
Hawkes LA, Broderick AC, Godfrey MH, Godley BJ (2009). Climate change and marine turtles.
Endangered Species Research,
7(2), 137-154.
Abstract:
Climate change and marine turtles
Marine turtles occupy a wide range of terrestrial and marine habitats, and many aspects of their life history have been demonstrated to be closely tied to climatic variables such as ambient temperature and storminess. As a group, therefore, marine turtles may be good indicators of climate change effects on coastal and marine habitats. Despite the small number of species in the taxon and a growing body of research in the field, the evidence base to predict resultant impacts of climate change remains relatively poor. We review the data from peer-reviewed publications to assess the likely impacts of climate change on marine turtles and highlight the types of data that would be most useful for an accurate assessment of future effects. The cumulative indications from these previous studies indicate that future research should focus on: (1) climate change effects on key habitats upon which turtles depend; (2) factors that influence nest site selection; (3) the consequences of skewed primary sex ratios; and (4) the effect of climate change on turtles at sea, for example range shifts and dietary breadth. Although it is too early to give detailed management recommendations, careful protection of coastlines along which turtles nest should be considered, as should the protection of beaches that produce male hatchlings, which may be of increased importance in the future. More active management approaches, for example translocation of eggs to suitable yet vacant nesting beaches, may be necessary to consider under worst-case scenarios. © Inter-Research 2009.
Abstract.
Campbell LM, Silver JJ, Gray NJ, Ranger S, Broderick AC, Fisher T, Godfrey MH, Gore S, Hodge KVD, Jeffers J, et al (2009). Co-management of sea turtle fisheries: Biogeography versus geopolitics. Marine Policy, 33, 137-145.
Blumenthal JM, Austin TJ, Bothwell JB, Broderick AC, Ebanks-Petrie G, Olynik JR, Orr MF, Solomon JL, Witt MJ, Godley BJ, et al (2009). Diving behavior and movements of juvenile hawksbill turtles Eretmochelys imbricata on a Caribbean coral reef.
Coral Reefs,
28(1), 55-65.
Abstract:
Diving behavior and movements of juvenile hawksbill turtles Eretmochelys imbricata on a Caribbean coral reef
As historically abundant spongivores, hawksbill turtles Eretmochelys imbricata likely played a key ecological role on coral reefs. However, coral reefs are now experiencing global declines and many hawksbill populations are critically reduced. For endangered species, tracking movement has been recognized as fundamental to management. Since movements in marine vertebrates encompass three dimensions, evaluation of diving behavior and range is required to characterize marine turtle habitat. In this study, habitat use of hawksbill turtles on a Caribbean coral reef was elucidated by quantifying diel depth utilization and movements in relation to the boundaries of marine protected areas. Time depth recorders (TDRs) and ultrasonic tags were deployed on 21 Cayman Islands hawksbills, ranging in size from 26.4 to 58.4 cm straight carapace length. Study animals displayed pronounced diel patterns of diurnal activity and nocturnal resting, where diurnal dives were significantly shorter, deeper, and more active. Mean diurnal dive depth (±SD) was 8 ± 5 m, range 2-20 m, mean nocturnal dive depth was 5 ± 5 m, range 1-14 m, and maximum diurnal dive depth was 43 ± 27 m, range 7-91 m. Larger individuals performed significantly longer dives. Body mass was significantly correlated with mean dive depth for nocturnal but not diurnal dives. However, maximum diurnal dive depth was significantly correlated with body mass, suggesting partitioning of vertical habitat by size. Thus, variable dive capacity may reduce intraspecific competition and provide resistance to degradation in shallow habitats. Larger hawksbills may also represent important predators on deep reefs, creating a broad ecological footprint over a range of depths. © 2008 Springer-Verlag.
Abstract.
Blumenthal JM, Austin TJ, Bell CDL, Bothwell JB, Broderick AC, Ebanks-Petrie G, Gibb JA, Luke KE, Olynik JR, Orr ME, et al (2009). Ecology of hawksbill turtles, Eretmochelys imbricata, on a western caribbean foraging ground.
Chelonian Conservation and Biology,
8(1), 1-10.
Abstract:
Ecology of hawksbill turtles, Eretmochelys imbricata, on a western caribbean foraging ground
We present results of an inwater research program focusing on basic ecology of juvenile hawksbill turtles (Eretmochelys imbricata) in the Cayman Islands. We made 206 captures of 135 hawksbills in Little Cayman and 103 captures of 97 hawksbills in Grand Cayman. The Cayman Islands aggregation demonstrated a broad size distribution (20.5-62.6 cm straight carapace length), slow growth rate (3.0 ± 0.9 cm/y), and multiple recaptures, suggesting long-term residence in some individuals. Demonstrated home range was small (mean distance from capture to recapture 545 ± 514 m, range 2-2080 m); although, an international tag return suggested a long-range developmental migration. Vertical features provided important habitat in Little Cayman, and larger turtles were generally captured in deeper waters. Behavior at sighting varied by habitat: resting, swimming, and feeding were observed in coral reef, reef wall, and hardbottom colonized by sponges and gorgonians, and resting was frequently observed in uncolonized hardbottom. Images obtained from underwater photographers show that hawksbills forage on sponges and occasionally on jellyfish. We observed an apparent commensal feeding relationship between hawksbills and 3 species of angelfish as well as aggressive interactions between hawksbills. We also documented causes of injury and mortality in the study area-including legal, illegal and incidental take, vessel collisions, hurricanes, and natural predation. © 2009 ChelonIan Research Foundation.
Abstract.
Pintus KJ, Godley BJ, McGowan A, Broderick AC (2009). Impact of clutch relocation on green turtle offspring.
Journal of Wildlife Management,
73(7), 1151-1157.
Abstract:
Impact of clutch relocation on green turtle offspring
For species with temperature-dependent sex determination, such as marine turtles, global climate change poses numerous threats. At the nesting beach, rising temperatures are predicted to further skew already female-biased sex ratios and increase embryonic mortality; sea-level rise and resultant coastal squeeze may leave few alternative breeding habitats in developed regions. As a result, clutch relocation, a commonly used management tool to reduce egg loss, may become necessary for safeguarding populations. Although studies have examined the impact of relocation on clutch success, few have examined the impact of this practice on the sex or phenotypic characteristics of hatchlings produced. We used a randomized block design experiment to examine effects of relocation on green turtle (Chelonia mydas) clutches. We compared hatching success, thermal conditions, and size (length and mass) of hatchlings from in situ control clutches with those subjected to 2 relocation methods, while controlling for maternal and other environmental effects. Relocated clutches did not vary significantly from control clutches in incubation temperature or inferred sex ratios during the critical middle third of incubation when sex is thought to be determined. Hatchling size was also unaffected by relocation. Both relocation methods, however, resulted in a 20 reduction in hatching success in comparison to in situ clutches. Clutch relocation is, however, likely to affect the population primary sex ratio, when clutches are relocated from sites in proximity to the sea where tidal inundation is a threat. Here, cooler conditions are likely to produce more males than are the warmer female-producing temperatures higher up the beach. For clutches at risk, relocation is a viable process and does not appear to affect hatchling size or predicted sex ratios if relocation sites are selected in areas utilized by other females. We urge caution, however, when moving clutches from potentially male-producing sites, particularly given predicted impacts of climate change on already female-biased sex ratios. © 2009 the Wildlife Society.
Abstract.
Fuller WJ, Broderick AC, Hooker SK, Witt MJ, Godley BJ (2009). Insights into habitat utilization by Green Turtles (Chelonia Mydas) during the inter-nesting period animal-borne digital cameras.
Marine Technology Society Journal,
43(3), 51-59.
Abstract:
Insights into habitat utilization by Green Turtles (Chelonia Mydas) during the inter-nesting period animal-borne digital cameras
Many marine turtle habitat utilization studies have historically relied on inferences from logged data or direct visual observation. Here we remotely investigate aspects of the habitat utilization of inter-nesting female green turtles (Chelonia mydas) nesting on the Mediterranean island of Cyprus. Using an animal- borne digital video camera set to take only still images, with an integrated time-depth recorder, we recorded a total of 2, 375 images and 2, 899 dives for two nesting female green turtles. Both turtles spent over 80% of their time at depths of 5 m or less. Photographic evidence allowed us to categorize subsurface behaviors from 66 of the deeper dives (turtle a with 40 dives and turtle B with 26 dives) containing more than 900 images into three categories: swimming, probable foraging and resting. Methodologically, our study highlights future utility in using camera technologies to clarify at-sea behavior of marineorganisms, with a view to generating reliable time budgets.
Abstract.
Inger R, Attrill MJ, Bearhop S, Broderick AC, Grecian WJ, Hodgson DJ, Sheehan E, Votier SC, Witt MJ, Godley BJ, et al (2009). Marine Renewable Energy: potential benefits to biodiversity? an urgent call for research.
Journal of Applied Ecology,
46, 1145-1153.
Abstract:
Marine Renewable Energy: potential benefits to biodiversity? an urgent call for research.
1. The evidence for anthropogenically induced climate change is overwhelming with the production of greenhouse gases from burning fossil fuels being a key driver. In response, many governments have initiated programmes of energy production from renewable sources.
2. The marine environment presents a relatively untapped energy source and offshore installations are likely to produce a significant proportion of future energy production. Wind power is the most advanced, with development of wave and tidal energy conversion devices expected to increase worldwide in the near future.
3. Concerns over the potential impacts on biodiversity of marine renewable energy installations (MREI) include: habitat loss, collision risks, noise and electromagnetic fields. These factors have been posited as having potentially important negative environmental impacts.
4. Conversely, we suggest that if appropriately managed and designed, MREI may increase local biodiversity and potentially benefit the wider marine environment. Installations have the capacity to act as both artificial reefs and fish aggregation devices, which have been used previously to facilitate restoration of damaged ecosystems, and de facto marine-protected areas, which have proven successful in enhancing both biodiversity and fisheries.
5. The deployment of MREI has the potential to cause conflict among interest groups including energy companies, the fishing sector and environmental groups. Conflicts should be minimized by integrating key stakeholders into the design, siting, construction and operational phases of the installations, and by providing clear evidence of their potential environmental benefits.
6. Synthesis and applications. MREI have the potential to be both detrimental and beneficial to the environment but the evidence base remains limited. To allow for full biodiversity impacts to be assessed, there exists an urgent need for additional multi and inter-disciplinary research in this area ranging from engineering to policy. Whilst there are a number of factors to be considered, one of the key decisions facing current policy makers is where installations should be sited, and, dependent upon site, whether they should be designed to either minimize negative environmental impacts or as facilitators of ecosystem restoration.
Abstract.
Author URL.
Inger R, Attrill MJ, Bearhop S, Broderick AC, James Grecian W, Hodgson DJ, Mills C, Sheehan E, Votier SC, Witt MJ, et al (2009). Marine renewable energy: Potential benefits to biodiversity? an urgent call for research.
Journal of Applied Ecology,
46(6), 1145-1153.
Abstract:
Marine renewable energy: Potential benefits to biodiversity? an urgent call for research
The evidence for anthropogenically induced climate change is overwhelming with the production of greenhouse gases from burning fossil fuels being a key driver. In response, many governments have initiated programmes of energy production from renewable sources. 2. The marine environment presents a relatively untapped energy source and offshore installations are likely to produce a significant proportion of future energy production. Wind power is the most advanced, with development of wave and tidal energy conversion devices expected to increase worldwide in the near future. 3. Concerns over the potential impacts on biodiversity of marine renewable energy installations (MREI) include: habitat loss, collision risks, noise and electromagnetic fields. These factors have been posited as having potentially important negative environmental impacts. 4. Conversely, we suggest that if appropriately managed and designed, MREI may increase local biodiversity and potentially benefit the wider marine environment. Installations have the capacity to act as both artificial reefs and fish aggregation devices, which have been used previously to facilitate restoration of damaged ecosystems, and de facto marine-protected areas, which have proven successful in enhancing both biodiversity and fisheries. 5. The deployment of MREI has the potential to cause conflict among interest groups including energy companies, the fishing sector and environmental groups. Conflicts should be minimized by integrating key stakeholders into the design, siting, construction and operational phases of the installations, and by providing clear evidence of their potential environmental benefits. 6. Synthesis and applications. MREI have the potential to be both detrimental and beneficial to the environment but the evidence base remains limited. To allow for full biodiversity impacts to be assessed, there exists an urgent need for additional multi and inter-disciplinary research in this area ranging from engineering to policy. Whilst there are a number of factors to be considered, one of the key decisions facing current policy makers is where installations should be sited, and, dependent upon site, whether they should be designed to either minimize negative environmental impacts or as facilitators of ecosystem restoration. © 2009 British Ecological Society.
Abstract.
Richardson PB, Bruford MW, Calosso MC, Campbell LM, Clerveaux W, Formia A, Godley BJ, Henderson AC, McClellan K, Newman S, et al (2009). Marine turtles in the Turks and Caicos Islands: Remnant rookeries, regionally significant foraging stocks, and a major turtle fishery.
Chelonian Conservation and Biology,
8(2), 192-204.
Abstract:
Marine turtles in the Turks and Caicos Islands: Remnant rookeries, regionally significant foraging stocks, and a major turtle fishery
This study reviews the status of marine turtles in the Turks and Caicos Islands (TCI) using data gathered during a multidisciplinary study involving field surveys, questionnaire-based interviews, and molecular genetics between 2002 and 2006. Large aggregations of foraging turtles in the archipelago's waters are dominated by juvenile green (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata), with provisional mixed-stock analysis of these species suggesting that the aggregations originate predominantly from larger and relatively proximate source rookeries in the Wider Caribbean region. This study also suggests that the islands host remnant nesting populations of turtles, with hawksbill turtle nests recorded more frequently than green and loggerhead turtle (Caretta caretta) nests. The TCI islanders retain a culture of turtle use, with the current regulated and legitimate harvest likely to be one of the largest among the Caribbean Islands. This study suggests that historic and current harvest of turtles and their eggs in the TCI may have contributed to the apparent decline in the country's nesting populations. In order to address this conservation concern, changes to the regulation and management of the TCI's turtle fishery are necessary, but further research is needed to inform these changes. © 2009 Chelonian Research Foundation.
Abstract.
Hartnoll RG, Broderick AC, Godley BJ, Saunders KE (2009). POPULATION STRUCTURE OF THE LAND CRAB <i>JOHNGARTHIA LAGOSTOMA</i> ON ASCENSION ISLAND (VOL 29, PG 57, 2009).
JOURNAL OF CRUSTACEAN BIOLOGY,
29(2), 281-281.
Author URL.
Hartnoll RG, Broderick AC, Godley BJ, Saunders KE (2009). Population structure of the land crab Johngarthia lagostoma on ascension Island.
Journal of Crustacean Biology,
29(1), 57-61.
Abstract:
Population structure of the land crab Johngarthia lagostoma on ascension Island
The population structure of the land crab Johngarthia lagostoma was studied on Ascension Island from 2005-2007, predominantly during the period of the seaward breeding migrations; approximately 4000 crabs were examined. Sex ratio varied according to location of sampling. Males predominated in permanent residential areas on high ground. Sexes were equal along migration routes to the sea. Females predominated in the breeding sites on the shore. Very few immature crabs (< 60 mm CW) were found. Males had modal and maximum sizes of 100-109 mm and 120 mm CW, females of 90-99 mm and 110 mm, respectively. An aging population is indicated. Crabs < 40 mm CW were all dark coloured, and colour variation into yellow, purple and intermediate morphs developed between 40-50 mm CW.Overall colour distribution of the population was 85% yellow, 5% intermediate, and 10% purple. Yellow morphs were more abundant in females (89%) than males (81%). The predominance of yellow morphs may be an adaptation to reduce heat stress.
Abstract.
Blumenthal JM, Abreu-Grobois FA, Austin TJ, Broderick AC, Bruford MW, Coyne MS, Ebanks-Petrie G, Formia A, Meylan PA, Meylan AB, et al (2009). Turtle groups or turtle soup: dispersal patterns of hawksbill turtles in the Caribbean.
Mol Ecol,
18(23), 4841-4853.
Abstract:
Turtle groups or turtle soup: dispersal patterns of hawksbill turtles in the Caribbean.
Despite intense interest in conservation of marine turtles, spatial ecology during the oceanic juvenile phase remains relatively unknown. Here, we used mixed stock analysis and examination of oceanic drift to elucidate movements of hawksbill turtles (Eretmochelys imbricata) and address management implications within the Caribbean. Among samples collected from 92 neritic juvenile hawksbills in the Cayman Islands we detected 11 mtDNA control region haplotypes. To estimate contributions to the aggregation, we performed 'many-to-many' mixed stock analysis, incorporating published hawksbill genetic and population data. The Cayman Islands aggregation represents a diverse mixed stock: potentially contributing source rookeries spanned the Caribbean basin, delineating a scale of recruitment of 200-2500 km. As hawksbills undergo an extended phase of oceanic dispersal, ocean currents may drive patterns of genetic diversity observed on foraging aggregations. Therefore, using high-resolution Aviso ocean current data, we modelled movement of particles representing passively drifting oceanic juvenile hawksbills. Putative distribution patterns varied markedly by origin: particles from many rookeries were broadly distributed across the region, while others would appear to become entrained in local gyres. Overall, we detected a significant correlation between genetic profiles of foraging aggregations and patterns of particle distribution produced by a hatchling drift model (Mantel test, r = 0.77, P < 0.001; linear regression, r = 0.83, P < 0.001). Our results indicate that although there is a high degree of mixing across the Caribbean (a 'turtle soup'), current patterns play a substantial role in determining genetic structure of foraging aggregations (forming turtle groups). Thus, for marine turtles and other widely distributed marine species, integration of genetic and oceanographic data may enhance understanding of population connectivity and management requirements.
Abstract.
Author URL.
Aiken JJ, Godley BJ, Broderick AC, Austin T, Ebanks-Petrie G, Hays GC (2009). Two hundred years after a commercial marine turtle fishery: the current status of marine turtles nesting in the Cayman Islands. Oryx, 35(02), 145-145.
2008
Broderick, A.C. Frett, G. Gore, S. (2008). Down But Not Out: Marine Turtles of the British Virgin Islands. Animal Conservation
Jackson AL, Broderick AC, Fuller WJ, Glen F, Ruxton GD, Godley BJ (2008). Sampling design and its effect on population monitoring: How much monitoring do turtles really need?.
Biological ConservationAbstract:
Sampling design and its effect on population monitoring: How much monitoring do turtles really need?
Marine turtles are a taxon of world-wide conservation concern. Effective long-term monitoring is hampered by the fact that populations are widely dispersed except during the breeding season. Thus most monitoring programmes focus on nesting beaches, necessitating resource intensive studies, often over months, that could conceivably, be less comprehensive and focus on more parsimonious sampling. We analyse 11 years of exhaustive monitoring data for two species of Mediterranean marine turtles (Chelonia mydas and Caretta caretta). We resample using a variety of plausible sub-sampling regimens to estimate the total annual nesting population. We project our dataset into the future applying a range of population change rates to explore how adopting a monitoring programme based on sub-sampling would, for example, affect our ability to detect population decline. We show that accurate annual population estimates can be achieved with as few as 14 days of survey effort providing monitoring spans the peak of nesting. Furthermore, the modelled impact of sampling-based monitoring suggests that the duration to detect population change is not increased greatly. Our findings have implications for all marine turtle monitoring and have applicability to other animal groups. It is often considered desirable to perform exhaustive monitoring, with aversion of basing policy recommendations on partial data. However, comprehensive long-term monitoring programmes, particularly in developing nations, although presenting a number of advantages, are often impossible. Accurate total annual censuses can be achieved through a variety of sub-sampling regimens without sacrificing the ability to detect changes in the population trends over time. In this example, a solid block of at least 3 weeks sampling that encompasses the peak of the nesting season is advised. © 2008 Elsevier Ltd. All rights reserved.
Abstract.
Jackson AL, Broderick AC, Fuller WJ, Glen F, Ruxton GD, Godley BJ (2008). Sampling design and its effect on population monitoring: How much monitoring do turtles really need?.
BIOLOGICAL CONSERVATION,
141(12), 2932-2941.
Author URL.
Broderick, A.C. Coyne, M.S. Formia, A. (2008). Satellite tracking highlights difficulties in the design of effective protected areas for leatherback turtles during the internesting period. Oryx
Godley BJ, Blumenthal JM, Broderick AC, Coyne MS, Godfrey MH, Hawkes LA, Witt MJ (2008). Satellite tracking of sea turtles: Where have we been and where do we go next?.
Endangered Species Research,
4, 3-22.
Author URL.
Mcgowan A, Broderick AC, Godley BJ (2008). Seabird populations of the Chagos Archipelago, Indian Ocean: an evaluation of IBA sites.
ORYX,
42(3), 424-429.
Author URL.
Leeney RH, Amies R, Broderick AC, Witt MJ, Loveridge J, Doyle J, Godley BJ (2008). Spatio-temporal analysis of cetacean strandings and bycatch in a UK fisheries hotspot. Biodiversity and Conservation
Fuller WJ, Broderick AC, Phillips RA, Silk JRD, Godley BJ (2008). Utility of geolocating light loggers for indicating at-sea movements in sea turtles. Endangered Species Research, 4, 139-146.
2007
McGowan A, Woodfield NK, Hilton G, Broderick AC, Godley BJ (2007). A rigorous assessment of the Avifauna of a small Caribbean Island: a case study in Anegada, British Virgin Islands.
Caribbean Journal of Science,
43(1), 99-116.
Abstract:
A rigorous assessment of the Avifauna of a small Caribbean Island: a case study in Anegada, British Virgin Islands
The avifauna of the British Virgin Islands (BVI) has received little attention from researchers. The lack of baseline information is therefore a major hindrance to the construction of management plans. Here we present detailed monitoring data on the species composition and numbers of each-species for the island of Anegada, BVI. We surveyed the birds of Anegada between November 2003 and March 2005 utilising a combination of coastal transects, wetland bird counts, point counts, and species-specific survey methods for nocturnal species. A total of 99 different species were recorded, with a large increase in the number of species and number of individuals centred around peak migration in September. Although there is a depauperate terrestrial bird community consisting of predominately generalist species, it holds important populations of regional avifauna. For example, it hosts five regionally important breeding seabird colonies and its wetlands provide an important stop-over and over-wintering site for many species of shorebirds and waterbirds. In addition, the Eastern salt ponds are also the only breeding site for the greater flamingo, Phoenicopterus ruber, within the territory. We discuss our findings within the current framework of regional conservation and provide recommendations for the implementation of a territory wide monitoring program as a first step towards meeting the UK's commitments under several multilateral environmental agreements. Copyright 2007 College of Arts and Science.
Abstract.
Woodfield, N.K. Hilton, G. Broderick, A.C. (2007). An assessment of the avifauna of a small remote island: a case study of Anegada, British Virgin Islands. Caribbean Journal of Science
Broderick AC, Coyne MS, Fuller WJ, Glen F, Godley BJ (2007). Correction for Broderick. <i>et al.</i>. Fidelity and over-wintering of sea turtles.
Proceedings of the Royal Society B: Biological Sciences,
274(1629), 3183-3183.
Abstract:
Correction for Broderick. et al.. Fidelity and over-wintering of sea turtles
. Correction for ‘Fidelity and over-wintering of sea turtles’ by Annette C. Broderick, Michael S. Coyne, Wayne J. Fuller, Fiona Glen and Brendan J. Godley (Proc. R. Soc. B
. 274
. 1533–1538.
(doi:
. 10.1098/rspb.2007.0211
. )).
.
. The scale bar in figure 2b was incorrect, and should read as follows: 5 km.
Abstract.
Broderick AC, Coyne MS, Fuller WJ, Glen F (2007). Fidelity and over-wintering of sea turtles. Proceedings of the Royal Society B Biological Sciences, 274(1617), 1533-1538.
Formia A, Broderick AC, Glen F, Godley BJ, Hays GC, Bruford MW (2007). Genetic composition of the Ascension Island green turtle rookery based on mitochondrial DNA: implications for sampling and diversity.
Endangered Species Research,
3, 145-158.
Author URL.
HAWKES LA, BRODERICK AC, GODFREY MH, GODLEY BJ (2007). Investigating the potential impacts of climate change on a marine turtle population. Global Change Biology, 0(0), 070621084512044-???.
Hawkes LA, Broderick AC, Godfrey MH, Godley BJ (2007). Investigating the potential impacts of climate change on marine turtles. Global Change Biology, 13(5), 923-932.
Solomon, J.L. Blumenthal, J.M. Austin, T.J. (2007). Monitoring and conservation of critically reduced marine turtle nesting populations: lessons from the Cayman Islands. Animal Conservation, 10, 39-47.
Hawkes LA, Broderick AC, Godfrey MS, Coyne MS, Godley BJ (2007). Only some like it hot: quantifying the environmental niche of loggerhead sea turtles. Diversity and Distributions, 13(4), 447-457.
Witt MJ, Broderick AC, Johns DJ, Martin C, Penrose R, Hoogmoed MS, Godley BJ (2007). Prey landscapes help identify potential foraging habitats for leatherback turtles in the NE Atlantic.
Marine Ecology Progress Series,
337, 231-243.
Abstract:
Prey landscapes help identify potential foraging habitats for leatherback turtles in the NE Atlantic
Identifying key marine megavertebrate habitats has become ever more important as concern increases regarding global fisheries bycatch and accelerated climate change. This will be aided by a greater understanding of the patterns and processes determining the spatiotemporal distribution of species of conservation concern. We identify probable foraging grounds for leatherback turtles in the NE Atlantic using monthly landscapes of gelatinous organism distribution constructed from Continuous Plankton Recorder Survey data. Using sightings data (n = 2013 records, 1954 to 2003) from 9 countries (UK, Ireland, France, Belgium, the Netherlands, Denmark, Germany, Norway and Sweden), we show sea surface temperatures of approximately 10 to 12°C most likely indicate the lower thermal threshold for accessible habitats during seasonal foraging migrations to high latitudes. Integrating maps of gelatinous plankton as a possible indicator of prey distribution with thermal tolerance parameters demonstrates the dynamic (spatial and temporal) nature of NE Atlantic foraging habitats. We highlight the importance of body size-related thermal constraints in structuring leatherback foraging populations and demonstrate a latitudinal gradient in body size (Bergmann's rule) where smaller animals are excluded from higher latitude foraging areas. We highlight the marine area of the European continental shelf edge as being both thermally accessible and prey rich, and therefore potentially supporting appreciable densities of foraging leatherbacks, with some suitable areas not yet extensively surveyed. © Inter-Research 2007.
Abstract.
Broderick, A.C. Johns, D.J. Martin, C.S. (2007). Prey landscapes help identify potential foraging habitats for leatherback turtles in the northeast Atlantic. Marine Ecology Progress Series, 337, 231-244.
Blumenthal, J.M. Broderick, A.C. Coyne, M.S. (2007). Satellite tracking of sea turtles: Where have we been and where do we go next?. Endangered Species Research, 3(16).
Witt MJ, Penrose R, Godley BJ (2007). Spatio-temporal patterns of juvenile marine turtle occurrence in waters of the European continental shelf.
Marine Biology,
151(3), 873-885.
Abstract:
Spatio-temporal patterns of juvenile marine turtle occurrence in waters of the European continental shelf
We present data spanning approximately 100 years regarding the spatial and temporal occurrence of marine turtle sightings and strandings in the northeast Atlantic from two public recording schemes and demonstrate potential signals of changing population status. Records of loggerhead (n = 317) and Kemp's ridley (n = 44) turtles occurring on the European continental shelf were most prevalent during the autumn and winter, when waters were coolest. In contrast, endothermic leatherback turtles (n = 1,668) were most common during the summer. Analysis of the spatial distribution of hard-shell marine turtle sightings and strandings highlights a pattern of decreasing records with increasing latitude. The spatial distribution of sighting and stranding records indicates that arrival in waters of the European continental shelf is most likely driven by North Atlantic current systems. Future patterns of spatial-temporal distribution, gathered from the periphery of juvenile marine turtles habitat range, may allow for a broader assessment of the future impacts of global climate change on species range and population size. © 2006 Springer-Verlag.
Abstract.
2006
Broderick AC, Frauenstein R, George T, Glen F (2006). Are green turtles globally endangered?. Global Ecology and Biogeography, 15(1), 21-26.
McGowan A, Gore S, Broderick A, Hilton G, Woodfield N, Godley B (2006). Breeding seabirds in the British Virgin Islands. Endangered Species Research, 2, 15-20.
Broderick, A.C. Gore, S. Hilton, G. (2006). Breeding seabirds in the British Virgin Islands.
Endangered Species Research,
3, 1-6.
Author URL.
Broderick, A.C. Campbell, L.M. Godley, B.J. (2006). Marine turtle fisheries in the UK Overseas Territories of the Caribbean: domestic legislation and the requirements of multilateral agreements. Journal of International Wildlife Law and Policy, 9, 223-246.
Godley, B.J. Dontaine, M.W. Bruford (2006). Mitochondrial DNA diversity and phylogeography of endangered green turtle (Chelonia mydas) populations in Africa. Conservation Genetics, 7, 353-369.
Hawkes LA, Broderick AC, Coyne MS, Godfrey MH, Lopez-Jurado LF, Lopez-Suarez P, Merino SE, Varo-Cruz N, Godley BJ (2006). Phenotypically linked dichotomy in sea turtle foraging strategies requires multiple conservation approaches. Current Biology, 16(10), 990-995.
Broderick, A.C. Godley, B.J. Hays, G.C. (2006). Rhythmic Throat Oscillations in Nesting Green Turtles (Chelonia mydas). Chelonian Conservation and Biology, 5, 299-301.
Solomon, J.L. Bell, C.D. Austin, T.J. (2006). Satellite tracking highlights the need for international cooperation in marine turtle management.
Endangered Species Research,
2, 51-61.
Author URL.
Broderick, A.C. Godley, B.J. Hays, G.C. (2006). Thermal control of hatchling emergence patterns in marine turtles. Journal of Experimental Marine Biology and Ecology, 334, 31-42.
Blumenthal, J.M. Austin, T.J. Solomon, J.L. (2006). Traditional Caymanian fishery may impede local marine turtle population recovery.
Endangered Species Research,
2, 63-69.
Author URL.
2005
Broderick, A.C. Godley, B.J. Hays, G.C. (2005). Patterns in the emergence of. green (Chelonia mydas) and loggerhead (Caretta caretta) turtle hatchlings from their nests. Marine Biology, 146, 1039-1049.
Parsons, J. Austin, T.J. Broderick, A.C. (2005). Some of them came home: the Cayman Turtle Farm headstarting project for the green turtle Chelonia mydas. Oryx, 39, 137-148.
Hawkes LA, Broderick, A.C. Godfrey, M.H. Godley, B.J. (2005). Status of nesting loggerhead turtles Caretta caretta at Bald Head Island (North Carolina, USA) after 24 years of intensive monitoring and conservation. Oryx, 39, 65-72.
2004
Broderick, A.C. Campbell, L.M. Ranger, S. (2004). An Assessment of the Status and Exploitation of Marine Turtles in the UK Overseas Territories in the Wider Caribbean. Final Project Report to the Department of Environment, Food and Rural Affairs and the Foreign and Commonwealth Office.
Hays GC, Broderick AC, Godley BJ, Luschi P, Nichols WJ, Chaloupka M, Parker D, Balazs G (2004). Tracking turtles to their death. Marine Ecology Progress Series, 283, 299-302.
2003
Broderick, A.C. Glen, F. Godley, B.J. (2003). Climate change and sea turtles: a 150-year reconstruction of incubation temperatures at a major marine turtle rookery. Global Change Biology, 9, 642-646.
Broderick, A.C. Godley, B.J. Hays, G.C. (2003). Incubation environment affects phenotype of naturally incubated green turtle hatchlings. Journal of the Marine Biological Association of the United Kingdom, 83, 1183-1186.
Åkesson, S. Broderick, A.C. Glen, F. (2003). Island finding ability of marine turtles. Proceedings of the Royal Society B, 270, S5-S7.
Lima, E. HS, M. Åkesson, S. (2003). Movement patterns of green turtles in Brazilian coastal waters described by satellite tracking and flipper tagging. Marine Ecology Progress Series, 253:279-288
Broderick, A.C. Glen, F. Godley, B.J. (2003). Multiple paternity assessed using microsatellite markers, in green turtles Chelonia mydas (Linnaeus, 1758) of Ascension Island, South Atlantic. Journal of Experimental Marine Biology and Ecology, 291, 149-160.
Broderick, A.C. Glen, F. Godley, B.J. (2003). Navigation by green turtles: which strategy do displaced adults use to find Ascension Island?. Oikos, 103, 363-372.
Broderick, A.C. Glen, F. Hays, G.C. (2003). Post-nesting movements and submergence patterns of loggerhead marine turtles in the Mediterranean assessed by satellite tracking. Journal of Experimental Marine Biology and Ecology, 287, 119-134.
Broderick, A.C. Godley, B.J. Luschi, P. (2003). Satellite telemetry suggests high levels of fishing-induced mortality in marine turtles. Marine Ecology Progress Series, 262, 305-309.
Glen, F. Godley, B.J. Hays, G.C. (2003). Variation in reproductive output of marine turtles. Journal of Experimental Marine Biology and Ecology, 288, 95-109.
2002
Glen, F. Broderick, A.C. Godley, B.J. (2002). Behavioural plasticity in a large marine herbivore: contrasting patterns of depth utilisation between two green turtle (Chelonia mydas) populations. Marine Biology, 141, 985-990.
Broderick, A.C. Godley, B.J. Lovell, P. (2002). Bi-phasal long-distance migration in green turtles. Animal Behaviour, 64, 895-898.
Broderick, A.C. Godley, B.J. Hays, G.C. (2002). Diving behaviour during the internesting interval for loggerhead turtles (Caretta caretta) nesting in Cyprus. Marine Ecology Progress Series, 227, 63-70.
Glen, F. Godley, B.J. Hays, G.C. (2002). Estimating the number of Green and Loggerhead Turtles nesting annually in the Mediterranean. Oryx, 36: 227-236
Barbosa, C. Indjai, B. Almeida, A. (2002). First census of the green turtle at Poilao, Bijagos Archipelago, Guinea-Bissau: the most important nesting colony on the Atlantic coast of Africa. Oryx, 36, 400-403.
Godley BJ, Broderick AC, Coyne MS, Richardson S (2002). Long-term satellite telemetry of the movements and habitat utilisation by green turtles in the Mediterranean. Ecography, 25(3), 352-362.
Broderick, A.C. Frauenstein, R. (2002). Reproductive seasonality and sexual dimorphism in green turtles. Marine Ecology Progress Series, 226, 125-133.
Broderick, A.C. Glen, F. (2002). Temperature dependent sex determination of Ascension Island green turtles. Marine Ecology Progress Series, 226, 115-124.
Broderick, A.C. Godley, B.J. West, S.A. (2002). The effects of incubation environment, sex and pedigree on the hatchling phenotype in a natural population of loggerhead turtles. Evolutionary Ecology Research, 4, 737-748.
Broderick, A.C. Glen, F. Godley, B.J. (2002). Water temperature and internesting intervals for loggerhead (Caretta caretta) and green (Chelonia mydas) sea turtles. Journal of Thermal Biology, 27, 429-432.
Broderick, A.C. Glen, F. Godley, B.J. (2002). Weight change associated with long-term fasting in a marine reptile: the case of green turtles (Chelonia mydas) at Ascension Island. Canadian Journal of Zoology, 80, 1299-1302.
2001
Broderick, A.C. Deeming, J. Godley, B.J. (2001). Dipteran infestation of loggerhead (Caretta caretta), and green (Chelonia mydas), sea turtle nests in northern Cyprus. Journal of natural History, 35, 573-581.
Broderick, A.C. Godley, B.J. Metcalfe, J.D. (2001). Dive angles for a green turtle (Chelonia mydas). Journal of Marine Biological Association(UK), 81, 683-686.
Godley B, Broderick, A.C. Mrosovsky, N. (2001). Estimating hatchling sex ratios of loggerhead turtles in Cyprus from incubation durations. Marine Ecology Progress Series, 210, 195-201.
Broderick AC, Godley BJ, Hays GC (2001). Metabolic heating and the prediction of sex ratios for green turtles (Chelonia mydas). Physiological and Biochemical Zoology, 74(2), 161-170.
McGowan A, Rowe, L.V. Broderick, A.C. Godley, B.J. (2001). Nest factors predisposing loggerhead sea turtle (Caretta caretta) clutches to infestation by dipteran larvae on northern Cyprus. Copeia, 2001(3), 808-812.
Godley B, Broderick, A.C. Hays, G.C. (2001). Nesting of green turtles Chelonia mydas at Ascension Island, South Atlantic. Biological Conservation, 97, 151-158.
Godley, B.J. Broderick, A.C. (2001). Nesting of the Green Turtle, Chelonia mydas, in the Mediterranean: a review of status and conservation needs. Zoology in the Middle East, 24, 45-74.
Åkesson S, Luschi P, Broderick AC, Glen F, Godley BJ, Papi F, Hays GC (2001). Oceanic long-distance navigation: Do experienced migrants use the earth's magnetic field?.
Journal of Navigation,
54(3), 419-427.
Abstract:
Oceanic long-distance navigation: Do experienced migrants use the earth's magnetic field?
Albatrosses and sea turtles are known to perform extremely long-distance journeys between disparate feeding areas and breeding sites located on small, isolated, oceanic islands or at specific coastal sites. These oceanic journeys, performed mainly over or through apparently featureless mediums, indicate impressive navigational abilities, and the sensory mechanisms used are still largely unknown. This research used three different approaches to investigate whether bi-coordinate navigation based on magnetic field gradients is likely to explain the navigational performance of wandering albatrosses in the South Atlantic and Indian Oceans and of green turtles breeding on Ascension Island in the South Atlantic Ocean. The possibility that magnetic field parameters can potentially be used in a bi-coordinate magnetic map by wandering albatrosses in their foraging area was investigated by analysing satellite telemetry data published in the literature. The possibilities for using bi-coordinate magnetic navigation varied widely between different areas of the Southern Oceans, indicating that a common mechanism, based on a bi-coordinate geomagnetic map alone, was unlikely for navigation in these areas. In the second approach, satellite telemetry was used to investigate whether Ascension Island green turtles use magnetic information for navigation during migration from their breeding island to foraging areas in Brazilian coastal waters. Disturbing magnets were applied to the heads and carapaces of the turtles, but these appeared to have little effect on their ability to navigate. The only possible effect observed was that some of the turtles with magnets attached were heading for foraging areas slightly south of the control turtles along the Brazilian coast. In the third approach, breeding female green turtles were deliberately displaced in the waters around Ascension Island to investigate which cues these turtles might use to locate and return to the island; the results suggested that cues transported by wind might be involved in the final stages of navigation.
Abstract.
Åkesson S, Luschi P, Papi F, Broderick AC, Glen F, Godley BJ, Hays GC (2001). Oceanic long-distance navigation:: Do experienced migrants use the Earth's magnetic field?.
JOURNAL OF NAVIGATION,
54(3), 419-427.
Author URL.
Luschi P, Åkesson, S. Broderick, A.C. Glen, F. Godley BJ, Papi F, Hays GC (2001). Testing animal navigational abilities in the ocean: displacement experiments on sea turtles. Behavioral Ecology and Sociobiology, 50, 528-534.
Åkesson, S. Broderick, A.C. Glen, F. (2001). The diving behaviour of green turtles undertaking oceanic migration to and from Ascension Island: dive durations, dive profiles and depth distribution. Journal of Experimental Biology, 204, 4093-4098.
Åkesson, S. Godley, B.J. Luschi, P. (2001). The implications of location accuracy for the interpretation of satellite tracking data. Animal Behaviour, 61, 1035-1040.
Hays GC, Ashworth, J.S. Barnsley, M.J. Broderick, A.C. Emery DR, Godley BJ, Henwood A, Jones EL (2001). The importance of sand albedo for the thermal conditions on sea turtle nesting beaches. Oikos, 93, 87-95.
Godley, B.J. Broderick, A.C. Glen, F. (2001). The movements and submergence behaviour of male green turtles at Ascension Island. Marine Biology, 139, 395-399.
Godley BJ, Broderick, A.C. Downie, J.R. Glen, F. Houghton JDR, Kirkwood I, Reece S, Hays GC (2001). Thermal conditions in nests of loggerhead turtles: further evidence suggesting female skewed sex ratios of hatchling production in the Mediterranean. Journal of Experimental Marine Biology and Ecology, 97, 45-63.
Broderick AC, Godley BJ, Hays GC (2001). Trophic status drives inter-annual variability in nesting numbers of marine turtles. Proceedings of the Royal Society B Biological Sciences, 268(1475), 1481-1487.
Godley, B.J. Broderick, A.C. Austin, T. (2001). Two hundred years after a commercial marine turtle fishery: the current status of marine turtles nesting in the Cayman Islands. Oryx, 35, 145-152.
2000
Hochscheid, S. Broderick, A.C. Godley, B.J. (2000). Diving behaviour of green turtles: dive depth, dive duration and activity levels. Marine Ecology Progress Series, 208, 297-298.
Godley, B.J. Reece, S. Downie, J.R. (2000). Incubation periods and sex ratios of green turtles: highly female biased hatchling production in the eastern Mediterranean. Marine Ecology Progress Series, 202, 273-281.
Adams, C.R. Broderick, A.C. Godley, B.J. (2000). The diving behaviour of green turtles at Ascension island. Animal Behaviour, 59, 577-586.
1999
Godley, B.J. (1999). Effect of tagging marine turtles on nesting behaviour and reproductive success. Animal Behaviour, 58, 587-591.
Godley, B.J. Broderick, A.C. (1999). Long-term thermal conditions on the nesting beaches of green turtles on Ascension Island. Marine Ecology Progress Series, 185, 297-299.
Godley, B.J. Broderick, A.C. Wilson, R.P. (1999). Reptilian diving: highly variable dive patterns in the green turtle (Chelonia mydas). Marine Ecology Progress Series, 185, 101-112.
Broderick, A.C. Moraghan, S. (1999). Short term effectiveness of Passive Integrated Transponders (PITs) used in the study of Mediterranean marine turtles. Chelonian Conservation and Biology, 3, 477-479.
1998
Gucu, A.C. Broderick, A.C. Furness, R.W. (1998). Interaction between marine turtles and artisanal fisheries in the eastern Mediterranean: a probable cause for concern?. Zoology in the Middle East, 16, 49-64.
Broderick, A.C. Catry, P. (1998). Marine Turtles in the Orango National Park (Bijagós Archipelago, Guinea-Bissau). Marine Turtle Newsletter, 81, 6-7.
Casale, P. Bradai, M.N. Godley, B.J. (1998). Molecular Resolution of Marine Turtle Stock composition in fishery bycatch: a case study in the Mediterranean. Molecular Ecology, 7, 1529-1542.
1997
Hancock, E.G. (1997). Insect infestation of Mediterranean marine turtle nests. Herpetological Review, 28(4), 190-191.
Godley, B.J. Kelly, A. Broderick, A.C. (1997). Marine turtle nesting in the Göksu Delta, Turkey, 1996. Marine Turtle Newsletter, 77, 17-19.
Godley, B.J. (1997). Observations of reproductive behaviour of male green turtles (Chelonia mydas) at a nesting beach in Cyprus. Chelonian Conservation and Biology, 2(4), 615-616.
1996
Godley, B.J. (1996). Population and nesting ecology of the green turtle, Chelonia mydas, and loggerhead turtle, Caretta caretta, in northern Cyprus. Zoology in the Middle East, 13, 27-46.
Broderick, A.C. (1996). Turtles and Tourist Marketing: a British Perspective. Marine Turtle Newsletter, 74, 16-17.
1995
Broderick, A.C. (1995). Northern Cyprus is critical habitat for Mediterranean turtles. Marine Turtle Newsletter, 69, 18-19.
1994
Godley, B.J. (1994). Marine turtles in Northern Cyprus. Results from Glasgow University Expeditions 1992-1993. Marine Turtle Newsletter, 67, 8-11.
1992
Broderick, A.C. (1992). Marine Turtles in Trinidad and Tobago. Marine Turtle Newsletter, 61, 15-18.
