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The olive ridley sea turtle is predominantly an epipelagic species with no apparent migration corridors. Research in feeding areas in other sea turtle species has identified aggregations of individuals from diverse backgrounds; however, no specific feeding areas have been identified for the olive ridley. We used mtDNA control region sequencing to identify the haplotype composition of 85 olive ridley turtles (adult and immature turtles from both sexes) captured and released in Central Mexican Pacific waters. Amplified fragments of the control region (751 bp) revealed the presence of 17 haplotypes (h = 0.5877 ± 0.0622 and π = 0.001698 ± 0.001185), and 16 of them were phylogenetically grouped within the lineage of the Eastern Pacific, but the haplotype Lo37 showed close evolutionary relationships with the lineage of the East Coast of India. Lagrangian drifter data showed that West–East transport from the Indo-Pacific to the tropical Eastern Pacific might be possible through passive drift. These results highlight the importance of more genetic studies offshore and the role of the ocean currents in the migratory behavior of olive ridleys, as well as the need to establish multinational strategies for the conservation and management of the species in international waters.

Globally distributed marine taxa are well suited for investigations of biogeographic impacts on genetic diversity, connectivity, and population demography. The sea turtle genus Lepidochelys includes the wide-ranging and abundant olive ridley (L. olivacea), and the geographically restricted and ‘Critically Endangered’ Kemp’s ridley (L. kempii). To investigate their historical biogeography, we analyzed a large dataset of mitochondrial DNA (mtDNA) sequences from olive (n = 943) and Kemp’s (n = 287) ridleys, and genotyped 15 nuclear microsatellite loci in a global sample of olive ridleys (n = 285). We found that the ridley species split ~ 7.5 million years ago, before the Panama Isthmus closure. The most ancient mitochondrial olive ridley lineage, located in the Indian Ocean, was dated to ~ 2.2 Mya. Both mitochondrial and nuclear markers revealed significant structure for olive ridleys between Atlantic (ATL), East Pacific (EP), and Indo-West Pacific (IWP) areas. However, the divergence of mtDNA clades was very recent (

Genetic monitoring of highly migratory endangered species is fundamental for effective management, particularly when they are shared internationally, and their populations need to be identified. A prime example is the green turtle, Chelonia mydas, whose genetic structure has been extensively studied in the Western Atlantic. Nevertheless, the identification of Cuban management units has remained uncertain, despite representing regionally significant nesting assemblages and occurring within a strategically central position. Compared to previous work, the current study used 800 bp mtDNA control region sequences and larger sample sizes (n = 189 from four nesting sites in SW Cuba). Of the 23 resolved haplotypes, nine were novel, fourteen were reported in Cuba for the first time, and eleven were endemic. Even though the distribution of nesting grounds barely spans 300 km, three management units were identified: Guanahacabibes-San Felipe (GUCB; with most of the endemic haplotypes), Isla de la Juventud (IJCB; with a predominance of haplotype CM-A13.1), and Cayo Largo (CLCB; with a haplotype profile closely related to Southern Caribbean rookeries). We discuss how the geographic distribution of mtDNA variation has likely been shaped by local and regional oceanic current patterns or derived from formerly hyperabundant regional populations. Genetic characterization of Cuban management units represents a significant contribution, filling critical knowledge gaps that have hampered the comprehensive mixed-stock analyses required to guide effective regional conservation strategies.

Globally distributed marine taxa are well suited for investigations of biogeographic impacts on genetic diversity, connectivity, and population demography. The sea turtle genusThe online version contains supplementary material available at 10.1007/s10592-022-01465-3.

Successful conservation of long-lived species requires reliable understanding of long-term trends and historical baselines. Using a green turtle (Chelonia mydas) foraging aggregation in the northern Gulf of California, Mexico as case study, we integrated scientific monitoring data with historic catch rate reconstructions derived from Local Ecological Knowledge (LEK). Models fit to LEK and monitoring data indicate that turtle abundance is increasing, but only after ~40 years of safeguarding the species’ nesting and foraging habitats in Mexico. However, as population declines occurred 75% faster than increases, and current abundance is at ~60% of historical baseline levels, indicating the need for sustained, long-term conservation actions. This study demonstrates the potential of linking LEK and ecological science to provide critical information for conservation, by establishing reference baselines and gauging population status, while promoting equitable and sustainable futures for local communities.

Olive ridleys (Lepidochelys olivacea) are the most numerous sea turtle species worldwide and also locally along the Pacific coast of Mexico. Published data on their distribution and nesting abundance along the coast of Nayarit and northern Jalisco, Mexico are, however, scarce. Here we describe the current extent of conservation activities and the history of efforts to protect sea turtles along this 394-km stretch of coastline. We found that 110 km (of the total of 394 km) are monitored by 18 sea turtle conservation programs, which in 2015 accounted for 43.2% of the total shoreline. Olive ridley sea turtle nesting was encountered on all monitored beaches. Our use of hatchery-protected nests as a measure of nesting levels is undoubtedly an underestimate of overall nesting in the region; however, it nevertheless provides a baseline of current nesting intensity in sites under conservation. Bahia de Banderas presented the highest nesting levels in the study area with 46.4% (3742 ± 904; mean ± SD) of t...

Temperature-dependent sex determination, or TSD, is a widespread phenomenon in reptiles. The shape of the relationship between constant incubation temperature and sex ratio defines the TSD pattern. The TSD pattern is considered a life-history parameter important for conservation because the wider the range of temperatures producing both sexes, the more resilient the species is to climate change impacts. We review the different published equations and methodologies that have been used to model TSD patterns. We describe a new flexible model that allows for an asymmetrical pattern around the pivotal temperature, which is the constant temperature producing both sexes in equal proportions. We show that Metropolis-Hastings with Markov chain produced by a Monte Carlo process has many advantages compared to maximum likelihood and is preferred. Finally, we apply the models to results from incubation experiments using eggs from the marine turtle Lepidochelys olivacea originating in Northeast Indian, East Pacific, and West Atlantic Regional Management Units (RMUs) and find large differences in pivotal temperatures but not in transitional ranges of temperatures.

In the eastern Pacific, peak olive ridley sea turtle (Lepidochelys olivacea) nesting occurs during the warmest months which coincide with the rainy season, yet as nesting takes place year-round, the small proportion of the nests laid during dry-low season are exposed to contrasting environmental conditions. Most of the studies on Pacific coast sea turtles have estimated sex ratios produced during the rainy-high season when the majority of conservation activities take place. Thus, dry-low season nests have on the whole been overlooked. Here we compared sex ratios and hatchling fitness for offspring produced during the dry and rainy seasons during 2015. We found that protected olive ridley clutches incubated during the dry-low season were exposed to lower temperatures, yielded higher hatchling success, produced 100% male offspring and larger, heavier hatchlings with better locomotor abilities. Our results highlight the critical value of monitoring and protecting sea turtle nests beyond the peak season (when nests can be protected more efficiently) to include low season nests, albeit at much lower densities, but which by yielding higher proportions of males and with greater locomotor capacities may be the key to population viability and adaptation to anthropogenic climate change.

Deriving robust historical population trends for long-lived species subject to human exploitation is challenging in scenarios where long-term scientific data are scarce or unavailable, as often occurs for species affected by small-scale fisheries and subsistence hunting. The importance of Local Ecological Knowledge (LEK) in data-poor scenarios is increasingly recognized in conservation, both in terms of uncovering historical trends and for engaging community stewardship of historic information. Building on previous work in marine historical ecology and local ecological knowledge, we propose a mixed socio-ecological framework to reliably document and quantify LEK to reconstruct historical population trends. Our method can be adapted by interdisciplinary teams to study various long-lived taxa with a history of human use. We demonstrate the validity of our approach by reconstructing long-term abundance data for the heavily-exploited East Pacific green turtle (Chelonia mydas) in Baja California, Mexico, which was driven to near extinction by a largely unregulated fishery from the early 1950s to the 1980s. No scientific baseline abundance data were available for this time-frame because recent biological surveys started in 1995 after all green turtle fisheries in the area were closed. To fill this data gap, we documented LEK among local fishers using ethnographic methods and obtained verified, qualitative data to understand the socio-environmental complexity of the green turtle fishery. We then established an iterative framework to synthesize and quantify LEK using generalized linear models (GLMs) and nonlinear regression (NLR) to generate a standardized, LEK-derived catch-per-unit-effort (CPUE) time-series. CPUE is an index of abundance that is compatible with contemporary scientific survey data. We confirmed the accuracy of LEK-derived CPUE estimates via comparisons with fisheries statistics available for 1962–1982. We then modeled LEK-derived abundance trends prior to 1995 using NLR. Our model established baseline abundance and described historical declines, revealing that the most critical (exponential) decline occurred between 1960 and 1980. This robust integration of LEK data with ecological science is of critical value for conservation and management, as it contributes to a holistic view of a species’ historic and contemporary conservation status.

Sea turtles and their nests face multiple threats on nesting beaches. Techniques have been developed to mitigate threats, these include relocating nests to fenced-off hatcheries or polystyrene boxes. The alteration of the nest’s natural environment may have direct effects on hatchling phenotype and locomotor performance. To test the effects of these two incubation conditions on proxies for hatchling fitness, we analysed locomotor performance (time to crawl 3 m and righting response) and phenotypic measures (weight and carapace length and width) of olive ridley sea turtle (Lepidochelys olivacea) hatchlings. We found that mean temperature was higher in hatcheries (30.5°C) than in polystyrene boxes (29.9°C) and that hatchlings incubated in polystyrene boxes had smaller straight carapace length (39.2 mm ± 2.0) and were significantly slower in crawl speed (CS) (0.0107 m s−1 ± 0.005) than those from hatcheries (SCL = 40.7 mm ± 1.3; CS = 0.018 m s−1 ± 0.005).

Background Congenital malformations in sea turtles have been considered sporadical. Research carried out in the Mexican Pacific revealed high levels of congenital malformations in the olive ridley, but little or no information is available for other species. We present results from analyses of external congenital malformations in olive ridley, green, and hawskbill sea turtles from Mexican rookeries on the Pacific coast and Gulf of Mexico. METHODS We examined 150 green and hawksbill nests and 209 olive ridley nests during the 2010 and 2012 nesting seasons, respectively. Olive ridley eggs were transferred to a hatchery and incubated in styrofoam boxes. Nests from the other two species were left in situ. Number of eggs, live and dead hatchlings, and eggs with or without embryonic development were registered. Malformation frequency was evaluated with indices of prevalence and severity. Results Mortality levels, prevalence and severity were higher in olive ridley than in hawksbill and green sea turtles. Sixty-three types of congenital malformations were observed in embryos, and dead or live hatchlings. Of these, 38 are new reports; 35 for wild sea turtles, three for vertebrates. Thirty-one types were found in hawksbill, 23 in green, and 59 in olive ridley. The head region showed a higher number of malformation types. Malformation levels in the olive ridley were higher than previously reported. Conclusion Olive ridleys seem more prone to the occurrence of congenital malformations than the other two species. Whether the observed malformation levels are normal or represent a health problem cannot be currently ascertained without long-term assessments. Birth Defects Research (Part A) 103:203–224, 2015. © 2015 Wiley Periodicals, Inc.

Marine turtle hatchling survival depends not only on suitable incubation temperatures allowing for viable embryo development but also adequate locomotor capacity to avoid predation while crawling from the beach to the sea and when swimming into the open ocean. To investigate the effects of temperature on swimming performance of olive ridley (Lepidochelys olivacea) hatchlings, we incubated eggs at different constant temperatures (24–34 °C) using a split-clutch approach. Swimming performance of hatchlings was tested and video-recorded for 24 h in static water under a day/night cycle (experiment 1) and for 30 min in continuously flowing water in the dark (experiment 2). Data from experiment 1 were evaluated visually to estimate the time of swimming activity. For experiment 2, we used software to calculate movement parameters from which hatchling performance was estimated. In both experiments, intermediate incubation temperatures (28–30 °C) were optimal not only for hatchling success and morphological dimensions but also for swimming performance, with 30 °C being the most favorable. Performance from hatchlings diminished with higher and lower temperatures, especially at the coldest range (26–27 °C). Phenotypic plasticity was observed from low and high incubation temperatures, with higher variation in performance among hatchlings from eggs incubated at 26–27 °C and 32–33 °C than for those incubated at 28–30 °C. Our results consistently showed that incubation temperature exerts the greatest influence on swimming performance and that maternal origin (clutch) has a significant effect on individual hatchling morphology. Given that the olive ridley year-round breeding leads to variable nest incubation temperatures in hot summers and cooler winter months, our results highlight the need for careful temperature management to produce hatchlings with optimal swimming capacities and, hence, highest survival probabilities.

The southeastern USA hosts the largest nesting concentration of loggerhead turtles Caretta caretta in the Atlantic. Regionally significant nesting also occurs along the Caribbean coast of Mexico, in Cuba, and in the Bahamas. Previous studies of North Atlantic loggerhead turtle rookeries based on a 380 bp fragment of the mitochondrial control region supported recognition of 8 demographically independent nesting populations (management units) in the Northwest Atlantic in addition to Cape Verde in the eastern Atlantic. Recent analysis of expanded mitochon- drial control region sequences revealed additional genetic diversity and increased population structure between western and eastern Atlantic loggerhead turtle rookeries. We se quenced an 817 bp mitochondrial DNA fragment in 2427 samples from nesting beaches in the southeastern USA, Cay Sal Bank, Bahamas, and Quintana Roo, Mexico. Pairwise FST comparisons, pairwise exact tests of population differentiation, and analysis of molecular variance support previously proposed management unit designations and additionally indicate that southeastern and south- western Florida rookeries should be recognized as distinct management units. Therefore, North- west Atlantic loggerhead turtle rookeries can be subdivided into 10 management units, corre- sponding to the beaches from (1) Virginia through northeastern Florida, (2) central eastern Florida, (3) southeastern Florida, (4) Dry Tortugas, Florida, (5) Cay Sal, Bahamas, (6) southwestern Cuba, (7) Quintana Roo, Mexico, (8) southwestern Florida, (9) central western Florida, and (10) northwestern Florida. We confirmed increased resolution of stock structure between many North- west Atlantic management units and the Cape Verde rookery with the expanded control region haplotypes.

Management of the critically endangered hawksbill turtle in the Wider Caribbean (WC) has been hampered by knowledge gaps regarding stock structure. We carried out a comprehensive stock structure re-assessment of 11 WC hawksbill rookeries using longer mtDNA sequences, larger sample sizes (N = 647), and additional rookeries compared to previous surveys. Additional variation detected by 740 bp sequences between populations allowed us to differentiate populations such as Barbados-Windward and Guadeloupe (F (st) = 0.683, P < 0.05) that appeared genetically indistinguishable based on shorter 380 bp sequences. POWSIM analysis showed that longer sequences improved power to detect population structure and that when N < 30, increasing the variation detected was as effective in increasing power as increasing sample size. Geographic patterns of genetic variation suggest a model of periodic long-distance colonization coupled with region-wide dispersal and subsequent secondary contact within the WC. Mismatch analysis results for individual clades suggest a general population expansion in the WC following a historic bottleneck about 100 000-300 000 years ago. We estimated an effective female population size (N (ef)) of 6000-9000 for the WC, similar to the current estimated numbers of breeding females, highlighting the importance of these regional rookeries to maintaining genetic diversity in hawksbills. Our results provide a basis for standardizing future work to 740 bp sequence reads and establish a more complete baseline for determining stock boundaries in this migratory marine species. Finally, our findings illustrate the value of maintaining an archive of specimens for re-analysis as new markers become available.

The hawksbill turtle is a critically endangered species that has been extensively exploited for centuries. Príncipe Island off western Africa harbours one of the species' major nesting populations in the eastern Atlantic, as well as hosting year-round foraging aggregations of juveniles, subadults and adult males. To gain insight into the population's genetic structure and relationships with regional stocks, we analysed mitochondrial DNA (mtDNA) sequences of nesting females (N = 9), foraging adult females (N = 11), adult males (N = 32), subadults (N = 15) and juveniles (N = 80). The nesting population was found to be fixed for a single haplotype (EATL), which had been previously reported in both western and eastern Atlantic hawksbill foraging sites but had no known rookery source prior to this study. Thus it is now possible to confirm the westward transoceanic movement by hawksbills originating from Príncipe Island. Our analyses demonstrated that the Príncipe Island nesting colony is genetically distinct from breeding populations in the western Atlantic and is phylogenetically linked with Indo-Pacific hawksbill clades, suggesting that Príncipe Island was most likely colonised by migrants from the Indian Ocean via the Cape of Good Hope in southern Africa. Mixed stock analyses revealed that the eastern Atlantic appears to be the primary foraging area for Príncipe hawksbills (75%) while most of the foraging juveniles in Príncipe waters originate from the Príncipe rookery (84%). Furthermore, the presence of Caribbean haplotypes at low frequencies (b 5%) suggests that eastward transatlantic movements by juveniles to distant foraging and developmental habitats also take place. Depleted hawksbill populations in the eastern Atlantic combined with the low genetic variability and high genetic distinctiveness found in the Príncipe nesting and foraging aggregations with respect to the western Atlantic, underscore the high degree of isolation and vulnerability of this eastern Atlantic stock. These characteristics are highly relevant for the development of effective conservation programmes and highlight the urgent need to consolidate international cooperation across regional boundaries

While little is known about hawksbill turtlesEretmochelys imbricatain the eastern Pacific Ocean, available information suggests that the population has declined substantially in recent decades and could be near extirpation in the region. To evaluate the current status of the population more effectively and to determine the feasibility of recovery efforts, a workshop of regional marine turtle specialists was held in June 2008 in Los Cóbanos, El Salvador. An international working group, Iniciativa Carey del Pacífico Oriental (ICAPO; Eastern Pacific Hawksbill Initiative in English), was established to consolidate information, promote conservation projects and raise awareness about the species. We present information derived from the workshop and compiled by the ICAPO working group since that time. Considering only records from 1 January 2007 to 31 May 2009 it appears that El Salvador hosts the majority of known hawksbill turtle nesting activity in the eastern Pacific, with 79.6% (n = 430) of all nesting observation records, and Mexico hosts the majority of records of hawksbill turtles at sea, with 60.3% (n = 44) of all in-water observation records. Although current abundance is very low, the pervasiveness of the species in the region suggests potential for conservation and recovery. Despite a historical paucity of research focusing on this population, the relatively large and steadily increasing number of records as a result of concerted efforts demonstrates the viability of the ICAPO network as an instrument to promote conservation of this species in the eastern Pacific.

Understanding the spatial movements of threatened marine species, such as sea turtles, is essential as a means of informing appropriate conservation management. Although novel tech- niques for tracking spatial movements are becoming more widely available (such as satellite track- ing), simple techniques such as mark-release-recapture remain effective. A flipper tagging and recovery program in Cuba tagged 210 loggerhead turtles over 14 yr and recovered 7% of the tags between 2 d and 3 yr later (mean = 296 d). All but one turtle was recaptured in Cuban waters, and data showed limited movement of turtles between northern and southern coasts. A further 50 turtles were recovered that had been tagged in foreign projects, the majority of which were from the USA (but also Mexico, The Bahamas, Canary Islands and Spain). A range of life stages of loggerhead tur- tles are found in Cuban waters year-round, and given that Cuba has the second largest reef in the Caribbean, it likely provides foraging habitat for significant numbers of loggerhead turtles from at least 6 different countries.

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.

A new mitochondrial DNA control region survey of the Barbados hawksbill nesting population was undertaken using larger sample sizes, reanalysis of previously reported samples, and new primers that increase the fragment length sequenced. This work revealed that haplotypes originally identified as endemic to Barbados were misread sequences. Genetic variants and a geographic subdivision on a finer scale than has previously been recorded for sea turtles were identified between the Barbados leeward and windward coasts, indicating the need for sampling at multiple sites to reveal comprehensive genetic variation at national scales. Using the updated haplotype profiles to re-estimate Barbados’ contribution to Caribbean hawksbill foraging grounds indicated a presence several-fold larger than previously calculated; a result congruent with the breeding population being one of the largest in the region.

The Yucatan Peninsula harbors the largest nesting population of hawksbill turtle Eretmochelys imbricata in the Atlantic Basin. In Mexico, one of the most significant conservation problems for this species is the lack of knowledge on migratory patterns and the location of feeding grounds for post-nesting hawksbill females. The main goal of this study was to gather information on the hawksbill's migratory patterns and the location of their feeding grounds by tracking 3 post-nest- ing females from Campeche state, Mexico. We attached satellite transmitters and tracked the 3 tur- tles for 166, 446 and 510 d, respectively. The turtles remained within Mexican territorial waters, reaching separate foraging grounds off the coast of Campeche and in the Mexican Caribbean. No significant relationships were observed between turtles' migrating behavior and sea-surface temper- ature or geostrophic currents. Spatial analysis of the data recorded in this study has generated novel information on hawksbill turtle migratory patterns and feeding grounds, which will aid in decision- making for hawksbill turtle conservation in the Yucatan Peninsula.

We investigated the dispersal, recruitment and migratory behaviour of the hawksbill sea turtle (Eretmochelys imbricata), among different life-history stages and demographic segments of the large hawksbill turtle aggregation at Mona Island, Puerto Rico. There were significant differences in both mitochondrial DNA (mtDNA) haplotype diversity and haplotype frequencies among the adult males, females and juveniles examined, but little evidence for temporal heterogeneity within these same groups sampled across years. Consistent with previous studies and the hypothesis of strong natal homing, there were striking mtDNA haplotype differences between nesting females on Mona Island and nesting females in other major Caribbean rookeries. Breeding males also showed strong, albeit weaker, genetic evidence of natal homing. Overall, Bayesian mixed-stock analysis suggests that Mona Island was the natal rookery for 79% (65-94%) of males in the aggregation. In contrast, the Mona Island rookery accounted for only a small subset of the new juvenile recruits to the foraging grounds or in the population of older juvenile hawksbills turtles on Mona. Instead, both new recruits and the older juvenile hawksbill turtles on Mona more likely recruited from other Caribbean rookeries, suggesting that a mechanism besides natal homing must be influencing recruitment to feeding habitats. The difference in the apparent degree of natal homing behaviour among the different life-history stages of hawksbill turtles at Mona Island underscores the complexity of the species' life-history dynamics and highlights the need for both local and regional conservation efforts.

We investigated the extent that the 2010 Deepwater Horizon oil spill potentially affected oceanic-stage sea turtles from populations across the Atlantic. Within an ocean-circulation model, particles were backtracked from the Gulf of Mexico spill site to determine the probability of young turtles arriving in this area from major nesting beaches. The abundance of turtles in the vicinity of the oil spill was derived by forward-tracking particles from focal beaches and integrating population size, oceanic-stage duration and stage-specific survival rates. Simulations indicated that 321 401 (66 199–397 864) green ( Chelonia mydas ), loggerhead ( Caretta caretta ) and Kemp's ridley ( Lepidochelys kempii ) turtles were likely within the spill site. These predictions compared favourably with estimates from in-water observations recently made available to the public (though our initial predictions for Kemp's ridley were substantially lower than in-water estimates, better agreement was obtained with modifications to mimic behaviour of young Kemp's ridley turtles in the northern Gulf). Simulations predicted 75.2% (71.9–76.3%) of turtles came from Mexico, 14.8% (11–18%) from Costa Rica, 5.9% (4.8–7.9%) from countries in northern South America, 3.4% (2.4–3.5%) from the United States and 1.6% (0.6–2.0%) from West African countries. Thus, the spill's impacts may extend far beyond the current focus on the northern Gulf of Mexico.

Congenital malformations in sea turtles have been considered sporadical. Research carried out in the Mexican Pacific revealed high levels of congenital malformations in the olive ridley, but little or no information is available for other species. We present results from analyses of external congenital malformations in olive ridley, green, and hawskbill sea turtles from Mexican rookeries on the Pacific coast and Gulf of Mexico.We examined 150 green and hawksbill nests and 209 olive ridley nests during the 2010 and 2012 nesting seasons, respectively. Olive ridley eggs were transferred to a hatchery and incubated in styrofoam boxes. Nests from the other two species were left in situ. Number of eggs, live and dead hatchlings, and eggs with or without embryonic development were registered. Malformation frequency was evaluated with indices of prevalence and severity.Mortality levels, prevalence and severity were higher in olive ridley than in hawksbill and green sea turtles. Sixty-three types of congenital malformations were observed in embryos, and dead or live hatchlings. Of these, 38 are new reports; 35 for wild sea turtles, three for vertebrates. Thirty-one types were found in hawksbill, 23 in green, and 59 in olive ridley. The head region showed a higher number of malformation types. Malformation levels in the olive ridley were higher than previously reported.Olive ridleys seem more prone to the occurrence of congenital malformations than the other two species. Whether the observed malformation levels are normal or represent a health problem cannot be currently ascertained without long-term assessments.

Molecular studies of sea turtles have shown that the frequency of multiple paternity (MP) varies between species, and between rookeries of the same species. This study uses nuclear microsatellite markers to compare the incidence of MP in two neighbouring olive ridley rookeries on the Pacific coast of Costa Rica, with contrasting nesting behaviours -- the 'arribada' population nesting at Ostional and the solitary nesters of Playa Hermosa. Using two highly polymorphic microsatellite markers, we tested 13 nests from each location and found a significant difference (P < 0.001) between the level of MP of the arribada rookery (92%- the highest found for marine turtles) and that of the solitary nesting rookery (30%). Additional analyses based on six microsatellite loci revealed no genetic differentiation between nesting females from the two locations, or between nesting females and attendant males from the Ostional breeding area. Sixty-nine per cent of the nests with MP were fathered by a minimum of three different males, and three nests showed evidence of at least four fathers. The results suggest that the differences observed in levels of MP between arribada and solitary rookeries are due to an effect of abundance of individuals on the mating system. This is supported by a regression analysis combining other paternity studies on sea turtles which shows that levels of MP increase with increasing abundance of nesting females.

To study the movement patterns of Green Seaturtle (Chelonia mydas) populations in the Caribbean region using Cuban habitats, tag-recapture data from local (Cuban National Tagging Program 1989- 2002) and international programs (1959-2002) were compiled and compared. Of the 742 turtles tagged in Cuba at fishing areas, nesting beaches and head-start facilities, 5.5% were recaptured, mostly outside of Cuban waters and with a majority of these (76.9%) off the coast of Nicaragua. Green Seaturtles tagged elsewhere and recaptured in Cuba included head-started juveniles from Grand Cayman (45% of the total), Mexico (2.3%), and Florida (1.8%); wild juveniles from the Bahamas (14.1%), Bermuda (5.4%), and Florida (1.5%); and adults from Tortuguero (26%), Florida, USA (1.3%), Mexico (1%), Venezuela (1.3%), and U.S. Virgin Islands (0.3%). Recaptures of tags placed at sites north of Cuba (Bermuda and the Bahamas) clustered in the northeast region of Cuba, whereas those from the south (Grand Cayman) were recaptured in southern areas. Recaptures from Tortuguero tags were concentrated in the southeast and westward regions of Cuba. Turtles from the Bahamas, Grand Cayman, and Bermuda showed the highest recapture rates in Cuban habitats, with 3.2, 1.9, and 1.0% of the total number of tags applied, respectively. These results for a broad range of populations and across life stages underscore the regionwide significance of Cuban sites as critical habitats or migratory corridors.

The main continental nesting rookeries of the east Pacific green turtle (EPGT), Chelonia mydas, on the Michoacan (Mexico) coast suffered drastic population declines following intense exploitation in the 1960s--1970s with annual abundance of nesting females plummeting from about 25,000 to an average of about 1400 between 1982 and 2001. Analyses of data from three nDNA microsatellite loci and 400 bp mtDNA control region sequences from a total of 123 nesting females sampled from four Michoacan rookeries found no evidence of population sub-structuring. The recent order of magnitude reduction in the population size shows no apparent impact on genetic diversity in either control region sequences (overall h = 0.48; pi = 0.0036) or microsatellite loci (overall Na = 20.8; Hexp = 0.895). Our estimates of annual effective female population size (Nef; from theta = 2Nemicron) of 1.9-2.3 x 10(3), in spite of being an order of magnitude below historical records, appear to be sufficient to allow recovery of this population without significant loss of genetic diversity. These findings highlight the importance of continued conservation to reverse the decline of this population before it becomes vulnerable to genetic erosion.

Despite the long debate of whether or not multiple mating benefits the offspring, studies still show contradicting results. Multiple mating takes time and energy. Thus, if females fertilize their eggs with a single mating, why to mate more than once? We investigated and inferred paternal identity and number of sires in 12 clutches (240 hatchlings) of green turtles (Chelonia mydas) nests at Tortuguero, Costa Rica. Paternal alleles were inferred through comparison of maternal and hatchling genotypes, and indicated multiple paternity in at least 11 of the clutches (92%). The inferred average number of fathers was three (ranging from 1 to 5). Moreover, regression analyses were used to investigate for correlation of inferred clutch paternity with morphological traits of hatchlings fitness (emergence success, length, weight and crawling speed); and size of the mother; and an environmental variable (incubation temperature). We suggest and propose two different comparative approaches for evaluating morphological traits and clutch paternity, in order to infer greater offspring survival. First, clutches coded by the exact number of fathers and second by the exact paternal contribution (fathers who gives greater proportion of the offspring per nest). We found significant differences (P < 0.05) in clutches coded by the exact number of fathers for all morphological traits. A general tendency of higher values in offspring sired by two to three fathers was observed for the length and weight traits. However, emergence success and crawling speed showed different trends which unable us to reach any further conclusion. The second approach analysing the paternal contribution showed no significant difference (P > 0.05) for any of the traits. We conclude that multiple paternity does not provide any extra benefit in the morphological fitness traits or the survival of the offspring, when analysed following the proposed comparative statistical methods.

Resistance to different antibiotics was found in 26 of the 30 strains analyzed, more than 70% of the strains analyzed were resistant to carbenicillin and ampicillin and a significant correlation was found between the resistance to both antibiotics. Plasmids were found in 80% of the strains analyzed, and 11 different plasmid profiles were observed. The most common profile obtained had only a 21.2-kbp plasmid, a significant correlation was found between the presence of this plasmid and resistance to carbenicillin, although some exceptions could be detected. Plasmids were cured from a cephalothin resistant strain and reintroduced into the plasmid-free cell and into Escherichia coli DH5alpha, both strains gained resistance to this antibiotic.

Chromosome numbers in somatic (naupliar) and germinal (adult male) cells of bisexual Artemia populations from the Yucatan Peninsula, SE Mexico (Celestun, CEL; Chuburna, CHUB; Xtampu, XTAM; and Las Coloradas, COL), were compared to those from San Francisco Bay (SFB) and Great Salt Lake (GSL) individuals. Diploid and haploid counts permitted a double-check on results. SFB and GSL samples had low variability in number of chromosomes, with strong modal values of 2n=42 and n=21, typical for A. franciscana. Chromosome counts in the Yucatan brine shrimp samples indicated deviations from the normal 2n=42 karyotype (heteroploidy): COL had chromosome modes of 2n=42 and n=21; CEL of 2n=40 and n=20; CHUB had 2n=44 and n=22; XTAM 2n=48 and n=24. Chromocenter abundance (heterocromatic blocks of highly repetitive DNA) among populations indicated that the North American brine shrimp from SFB and GSL had a mean of 15.9 and 15.1 chromocenters, respectively. From the Yucatan brine shrimp, COL had a variable number of chromocenters, ranging from 5 to 15 with a mean value of 9.9. The other three Artemia populations had much fewer chromocenters (CEL 1–3, XTAM 1–8, and CHUB 1–4). Heteromorphic sex chromosomes were apparent in some Yucatan karyotypes preparations. The haplotype condition in the Yucatan Artemia populations, though similar to that found in some Italian A. salina populations, is reported for the first time in New World Artemia. This cytological characteristic of the Yucatan Artemia, in conjunction with their morphological and allozyme differentiation, could provide new insight for the role of chromosome rearrangements in the evolutionary process of Artemia in the New World.

Despite the long debate of whether or not multiple mating benefits the offspring, studies still show contradicting results. Multiple mating takes time and energy. Thus, if females fertilize their eggs with a single mating, why to mate more than once? We investigated and inferred paternal identity and number of sires in 12 clutches (240 hatchlings) of green turtles (Chelonia mydas) nests at Tortuguero, Costa Rica. Paternal alleles were inferred through comparison of maternal and hatchling genotypes, and indicated multiple paternity in at least 11 of the clutches (92%). The inferred average number of fathers was three (ranging from 1 to 5). This in returns suggests that most females successfully got fecundated by at least three males. Moreover, regression analyses were used to investigate for correlation of inferred clutch paternity with morphological traits of hatchlings fitness (emergence success, length, weight and crawling speed); and size of the mother; and an environmental variable (incubation temperature). We suggest and propose two different comparative approaches for evaluating morphological traits and clutch paternity, in order to infer greater offspring survival. First, clutches coded by the exact number of fathers and second by the exact paternal contribution (fathers who gives greater proportion of the offspring per nest). We found significant differences (P < 0.05) in clutches coded by the exact number of fathers for all morphological traits, where a tendency of higher values in offspring sired by two to three fathers was found. The second approach analysing the paternal contribution showed no significant difference (P > 0.05) for any of the traits. The main conclusion is that multiple mating analysed by the exact number of inferred fathers significantly affects the survival of the offspring regardless of morphological trait measured.

Two groups of nauplii from the brine shrimp ( Artemia franciscana ) were enriched with different bacteria, and the dynamics of bacterial uptake by the nauplii were observed. This study showed that the efficiency of Artemia nauplii in bioencapsulating bacteria strongly depends on the type of bacteria used, time of exposure, and status (live or dead) of the bacteria.

The nesting colony of green sea turtles (Chelonia mydas) at Guanahacabibes Peninsula Biosphere Reserve and National Park is one of the largest in the Cuban archipelago; however, little information about its nesting ecology is available. Temporal and spatial variation in nesting and reproductive success as well as morphometric characteristics of gravid females were used to ecologically characterize this colony. Nine beaches of the Southernmost coast of Guanahacabibes Peninsula were monitored for 14 years (1998-2012) to determine green turtle nesting activity, from May to September (peak nesting season in this area). Beach dimensions were measured to determine nest density using the length and the area. Afterward the beaches were divided in two categories, index and secondary. Females were measured and tagged to compare new tagged females (823) with returning tagged females (140). Remigration interval was also determined. Temporal variation was identified as the annual number of nesting emergences and oviposits per female, with apparent peaks in reproductive activity on a biennial cycle in the first six years followed by periods of annual increase in nest number (2003-2008) and periods of decreasing number of nests (2010-2012). We also found intra-seasonal variation with the highest nesting activity in July, particularly in the second half of the month. The peak emergence time was 22:00-02:00 hr. In terms of spatial variation, smaller beaches had the highest nest density and nesting was more frequent 6-9m from the high tide line, where hatchling production was maximized although hatchling success was high on average, above 80%. Morphometric analysis of females was made and newly tagged turtles were smaller on average than remigrants. Our results are only a first attempt at characterizing Guanahacabibes' populations but have great value for establishing conservation priorities within the context of national management plans, and for efficient monitoring and protection of nesting beaches.

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 ofjuvenile 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.

Previous genetic studies have demonstrated that natal homing shapes the stock structure of marine turtle nesting populations. However, widespread sharing of common haplotypes based on short segments of the mitochondrial control region often limits resolution of the demographic connectivity of populations. Recent studies employing longer control region sequences to resolve haplotype sharing have focused on regional assessments of genetic structure and phylogeography. Here we synthesize available control region sequences for loggerhead turtles from the Mediterranean Sea, Atlantic, and western Indian Ocean basins. These data represent six of the nine globally significant regional management units (RMUs) for the species and include novel sequence data from Brazil, Cape Verde, South Africa and Oman. Genetic tests of differentiation among 42 rookeries represented by short sequences (380 bp haplotypes from 3,486 samples) and 40 rookeries represented by long sequences (~800 bp haplotypes from 3,434 samples) supported the distinction of the six RMUs analyzed as well as recognition of at least 18 demographically independent management units (MUs) with respect to female natal homing. A total of 59 haplotypes were resolved. These haplotypes belonged to two highly divergent global lineages, with haplogroup I represented primarily by CC-A1, CC-A4, and CC-A11 variants and haplogroup II represented by CC-A2 and derived variants. Geographic distribution patterns of haplogroup II haplotypes and the nested position of CC-A11.6 from Oman among the Atlantic haplotypes invoke recent colonization of the Indian Ocean from the Atlantic for both global lineages. The haplotypes we confirmed for western Indian Ocean RMUs allow reinterpretation of previous mixed stock analysis and further suggest that contemporary migratory connectivity between the Indian and Atlantic Oceans occurs on a broader scale than previously hypothesized. This study represents a valuable model for conducting comprehensive international cooperative data management and research in marine ecology.

A new system named AquaPlak® designed for evaluating heterotrophic bacteria and those belonging to the genus Vibrio was compared to the standard method of total viable count by spread plating. Water samples from a shrimp farm were evaluated by the two procedures over a 3-month period. The spread plating technique gave significantly higher viable counts for both Vibrio and heterotrophic bacteria than the AquaPlak® system.

The Kemp's ridley sea turtle (Lepidochelys kempi) is restricted to the warm temperate zone of the North Atlantic Ocean, whereas the olive ridley turtle (L. olivacea) is globally distributed in warm-temperate and tropical seas, including nesting colonies in the North Atlantic that nearly overlap the range of L. kempi. To explain this lopsided distribution, Pritchard (1969) proposed a scenario in which an ancestral taxon was divided into Atlantic and Pacific forms (L. kempi and L. olivacea, respectively) by the Central American land bridge. According to this model, the olive ridley subsequently occupied the Pacific and Indian Oceans and recently colonized the Atlantic Ocean via southern Africa. To assess this biogeographic model, a 470 bp sequence of the mtDNA control region was compared among 89 ridley turtles, including the sole L. kempi nesting population and 7 nesting locations across the range of L. olivacea. These data confirm a fundamental partition between L. olivacea and L. kempi (p=0.052-0.069), shallow separations within L. olivacea (p=0.002-0.031), and strong geographic partitioning of mtDNA lineages. The most divergent L. olivacea haplotype is observed in the Indo-West Pacific region, as are the central haplotypes in a parsimony network, implicating this region as the source of the most recent radiation of olive ridley lineages. The most common olive ridley haplotype in Atlantic samples is distinguished from an Indo-West Pacific haplotype by a single nucleotide substitution, and East Pacific samples are distingushed from the same haplotype by two nucleotide substitutions. These shallow separations are consistent with the recent invasion of the Atlantic postulated by Pritchard (1969), and indicate that the East Pacific nesting colonies were also recently colonized from the Indo-West Pacific region. Molecular clock estimates place these invasions within the last 300,000 years.

The nesting colony of green sea turtles (Chelonia mydas) at Guanahacabibes Peninsula Biosphere Reserve and National Park is one of the largest in the Cuban archipelago; however, little information about its nesting ecology is available. Temporal and spatial variation in nesting and reproductive success as well as morphometric characteristics of gravid females were used to ecologically characterize this colony. Nine beaches of the Southernmost coast of Guanahacabibes Peninsula were monitored for 14 years (1998-2012) to determine green turtle nesting activity, from May to September (peak nesting season in this area). Beach dimensions were measured to determine nest density using the length and the area. Afterward the beaches were divided in two categories, index and secondary. Females were measured and tagged to compare new tagged females (823) with returning tagged females (140). Remigration interval was also determined. Temporal variation was identified as the annual number of nesting emergences and oviposits per female, with apparent peaks in reproductive activity on a biennial cycle in the first six years followed by periods of annual increase in nest number (2003-2008) and periods of decreasing number of nests (2010-2012). We also found intra-seasonal variation with the highest nest- ing activity in July, particularly in the second half of the month. The peak emergence time was 22:00-02:00hr. In terms of spatial variation, smaller beaches had the highest nest density and nesting was more frequent 6-9m from the high tide line, where hatchling production was maximized although hatchling success was high on average, above 80%. Morphometric analysis of females was made and newly tagged turtles were smaller on average than remigrants. Our results are only a first attempt at characterizing Guanahacabibes' populations but have great value for establishing conservation priorities within the context of national management plans, and for efficient monitoring and protection of nesting beaches.Rev. Biol. Trop. 61 (4): 1935-1945. Epub 2013 December 01.

The nesting colony of green sea turtles (Chelonia mydas) at Guanahacabibes Peninsula Biosphere Reserve and National Park is one of the largest in the Cuban archipelago; however, little information about its nesting ecology is available. Temporal and spatial variation in nesting and reproductive success as well as morphometric characteristics of gravid females were used to ecologically characterize this colony. Nine beaches of the Southernmost coast of Guanahacabibes Peninsula were monitored for 14 years (1998-2012) to determine green turtle nesting activity, from May to September (peak nesting season in this area). Beach dimensions were measured to determine nest density using the length and the area. Afterward the beaches were divided in two categories, index and secondary. Females were measured and tagged to compare new tagged females (823) with returning tagged females (140). Remigration interval was also determined. Temporal variation was identified as the annual number of nesting emergences and oviposits per female, with apparent peaks in reproductive activity on a biennial cycle in the first six years followed by periods of annual increase in nest number (2003-2008) and periods of decreasing number of nests (2010-2012). We also found intra-seasonal variation with the highest nesting activity in July, particularly in the second half of the month. The peak emergence time was 22:00-02:00hr. In terms of spatial variation, smaller beaches had the highest nest density and nesting was more frequent 6-9m from the high tide line, where hatchling production was maximized although hatchling success was high on average, above 80%. Morphometric analysis of females was made and newly tagged turtles were smaller on average than remigrants. Our results are only a first attempt at characterizing Guanahacabibes’ populations but have great value for establishing conservation priorities within the context of national management plans, and for efficient monitoring and protection of nesting beaches. La colonia de Tortuga verde (Chelonia mydas) que anida en la Península de Guanahacabibeses es una de las más grandes del archipiélago cubano pero existe poca información disponible sobre la misma. Por ello utilizamos la variación espacial y temporal de la anidación así como el éxito reproductivo y las características morfométricas de las hembras grávidas para realizar la primera caracterización ecológica de esta colonia. Se estudiaron nueve playas durante 14 años (1998-2012) desde mayo hasta septiembre (pico de anidación). Estas se dividieron en dos categorías: índices y secundarias. Las hembras fueron medidas y marcadas para comparar las nuevas hembras marcadas (823) con las remigrantes (140). Se detectó una variación temporal en la anidación a tres niveles: interanual, dentro de la temporada y durante la noche. Se observa un ciclo bienal en los primeros seis años, luego un incremento anual (2003-2008) seguido por un período de decrecimiento en las anidaciones (2010-2012). Dentro de la temporada se encontró un pico en el mes de julio aunque cambia de la primera quincena a la segunda en años diferentes y la hora de emergencia preferentemente de 22:00-02:00hr. En la variación espacial, las playas pequeñas tuvieron mayor densidad de anidación, especialmente entre los 6-9m hasta la línea media de marea alta, donde se maximiza la producción de neonatos, aunque el éxito de emergencia de los neonatos se mantuvo como promedio por encima del 80% en toda la playa. Morfométricamente las hembras remigrantes resultaron mayores como promedio que las marcadas por primera vez. Estos resultados son una primera aproximación para la caracterización de la colonia de Guanahacabibes pero tienen gran valor para establecer prioridades de conservación dentro del contexto de los planes de manejo nacionales así como para garantizar un monitoreo eficiente y la protección de las playas de anidación.

Juvenile loggerhead turtles (Caretta caretta) have recently been documented in the vicinity of Baja California and thousands of these animals have been captured in oceanic fisheries of the North Pacific. The presence of loggerhead turtles in the central and eastern North Pacific is a prominent enigma in marine turtle distribution because the nearest documented nesting concentrations for this species are in Australia and Japan, over 10,000 km from Baja California. To determine the origin of the Baja California feeding aggregate and North Pacific fishery mortalities, samples from nesting areas and pelagic feeding aggregates were compared with genetic markers derived from mtDNA control region sequences. Overall, 57 of 60 pelagic samples (95%) match haplotypes seen only in Japanese nesting areas, implicating Japan as the primary source of turtles in the North Pacific Current and around Baja California. Australian nesting colonies may contribute the remaining 5% of these pelagic feeding aggregates. Juvenile loggerhead turtles apparently traverse the entire Pacific Ocean, approximately one-third of the planet, in the course of developmental migrations, but mortality in high-seas fisheries raises concern over the future of this migratory population.

Mitochondrial DNA analyses have been useful for resolving maternal lineages and migratory behavior to foraging grounds (FG) in sea turtles. However, little is known about source rookeries and haplotype composition of foraging green turtle aggregations in the southeastern Pacific. We used mitochondrial DNA control region sequences to identify the haplotype composition of 55 green turtles, Chelonia mydas, captured in foraging grounds of Gorgona National Park in the Colombian Pacific. Amplified fragments of the control region (457 bp) revealed the presence of seven haplotypes, with haplotype (h) and nucleotide (π) diversities of h = 0.300±0.080 and π = 0.009±0.005 respectively. The most common haplotype was CMP4 observed in 83% of individuals, followed by CMP22 (5%). The genetic composition of the Gorgona foraging population primarily comprised haplotypes that have been found at eastern Pacific rookeries including Mexico and the Galapagos, as well as haplotypes of unknown stock origin that likely originated from more distant western Pacific rookeries. Mixed stock analysis suggests that the Gorgona FG population is comprised mostly of animals from the Galapagos rookery (80%). Lagrangian drifter data showed that movement of turtles along the eastern Pacific coast and eastward from distant western and central Pacific sites was possible through passive drift. Our results highlight the importance of this protected area for conservation management of green turtles recruited from distant sites along the eastern Pacific Ocean.

Where conservation resources are limited and conservation targets are diverse, robust yet flexible priority-setting frameworks are vital. Priority-setting is especially important for geographically widespread species with distinct populations subject to multiple threats that operate on different spatial and temporal scales. Marine turtles are widely distributed and exhibit intra-specific variations in population sizes and trends, as well as reproduction and morphology. However, current global extinction risk assessment frameworks do not assess conservation status of spatially and biologically distinct marine turtle Regional Management Units (RMUs), and thus do not capture variations in population trends, impacts of threats, or necessary conservation actions across individual populations. To address this issue, we developed a new assessment framework that allowed us to evaluate, compare and organize marine turtle RMUs according to status and threats criteria. Because conservation priorities can vary widely (i.e. from avoiding imminent extinction to maintaining long-term monitoring efforts) we developed a ‘‘conservation priorities portfolio’’ system using categories of paired risk and threats scores for all RMUs (n = 58). We performed these assessments and rankings globally, by species, by ocean basin, and by recognized geopolitical bodies to identify patterns in risk, threats, and data gaps at different scales. This process resulted in characterization of risk and threats to all marine turtle RMUs, including identification of the world’s 11 most endangered marine turtle RMUs based on highest risk and threats scores. This system also highlighted important gaps in available information that is crucial for accurate conservation assessments. Overall, this priority-setting framework can provide guidance for research and conservation priorities at multiple relevant scales, and should serve as a model for conservation status assessments and prioritysetting for widespread, long-lived taxa.

BackgroundResolving threats to widely distributed marine megafauna requires definition of the geographic distributions of both the threats as well as the population unit(s) of interest. In turn, because individual threats can operate on varying spatial scales, their impacts can affect different segments of a population of the same species. Therefore, integration of multiple tools and techniques--including site-based monitoring, genetic analyses, mark-recapture studies and telemetry--can facilitate robust definitions of population segments at multiple biological and spatial scales to address different management and research challenges.Methodology/principal findingsTo address these issues for marine turtles, we collated all available studies on marine turtle biogeography, including nesting sites, population abundances and trends, population genetics, and satellite telemetry. We georeferenced this information to generate separate layers for nesting sites, genetic stocks, and core distributions of population segments of all marine turtle species. We then spatially integrated this information from fine- to coarse-spatial scales to develop nested envelope models, or Regional Management Units (RMUs), for marine turtles globally.Conclusions/significanceThe RMU framework is a solution to the challenge of how to organize marine turtles into units of protection above the level of nesting populations, but below the level of species, within regional entities that might be on independent evolutionary trajectories. Among many potential applications, RMUs provide a framework for identifying data gaps, assessing high diversity areas for multiple species and genetic stocks, and evaluating conservation status of marine turtles. Furthermore, RMUs allow for identification of geographic barriers to gene flow, and can provide valuable guidance to marine spatial planning initiatives that integrate spatial distributions of protected species and human activities. In addition, the RMU framework--including maps and supporting metadata--will be an iterative, user-driven tool made publicly available in an online application for comments, improvements, download and analysis.