Sea Turtle Species Research Articles

Trace elements and high sulfur levels in the blood of rehabilitated eastern Mediterranean Sea green sea turtles (Chelonia mydas)

The Eastern Mediterranean Sea (EMS) exhibits high temperature and salinity, low levels of biologic production and is considered oligotrophic. Nonetheless, it is also a hotspot of biodiversity, with several important endangered flagship species, including several species of sea turtles. These turtles serve as bioindicators for the health of their ecologic systems, due to changes in diet, habitat and migration patterns that characterize different stages in their lives. This study covered 100 blood samples taken between 2008 and 2019 from 72 green sea turtles (Chelonia mydas) tested for 67 elements, some of which carry toxic potential. The turtles were treated at the Israeli Sea Turtle Rescue Center (ISTRC) after being rescued from sea, exhibiting a variety of health conditions and Injuries. The data were compared to similar studies worldwide and serve as a basis for monitoring the health status of the green sea turtles' EMS populations. The results of all animals presented noticeably high levels of sulfur – an order of magnitude higher than sea turtles from other locations around the world. This paper discusses the possible origins of this element, as well as its potential effects, while raising the question regarding the ability of these sea turtles to endure such sulfur levels.

Methods used in sea turtle genetic and molecular studies

Sea turtles have a tropical and subtropical distribution and can be found in nearly all seas and oceans. They have been the subject of considerable genetic research. However, it does not yet appear that the molecular techniques used for these genetic studies follow a consensus or universal set of tools to be followed for subsequent studies. This is not desirable since it may preclude data exchange and use among studies. Thus, the aim of this review was to survey the main genetic and molecular methods used for sea turtle research worldwide. To achieve this goal, a total of 95 scientific papers were compiled from online databases. We considered articles that used molecular tools for genetic analysis and provided detailed locality data. The following aspects were assessed: species studied, local of sample collection, type of tissue used for molecular studies and type of genetic material used. The seven known sea turtle species have different distribution patterns, with some overlapping of occurrence. Chelonia mydas has been studied genetically along the coasts of all continents. Skin is the most common type of tissue used for molecular analyses. From genetic studies on sea turtles, it is possible to verify the occurrence of hybridism. This phenomenon is relevant to the conservation of the species and was reported in six articles on this topic. Therefore, it is considered that genetic and molecular assays in sea turtles are important tools for biological evaluation and protection. The aim was to survey the main methods used in genetic and molecular research on marine turtles. Keywords: DNA, Chelonian, Testudines, marine turtles

Recommendation of consensus definition of sea turtle fibropapillomatosis

AbstractSea turtle fibropapillomatosis (FP) is an emerging transboundary contagious disease that affected concomitantly two different marine hot spots in the Northern Atlantic Ocean and in the South China Sea at the beginning of the twentieth century. FP reached a panzootic status in the 1990s in green turtle (Chelonia mydas) populations, with increased risks of emergence and spread of the disease which have been correlated with climate induced terrestrial and oceanic physical and chemical changes. During 2023–2024, scientific experts performed a bibliographic review and recommend the consensus definition of sea turtle fibropapillomatosis. FP is an emerging transboundary viral terrestrial and aquatic contagious neoplastic syndrome involving cancerous molecular transmission pathways, which may affect all species of sea turtles at all life stages. The diagnosis of the most common verrucous form of FP is pathognomonic by visual examination of a sea turtle. We summarize the main clinical characteristics of FP, moderated by a degree of confidence of research findings adapted from the Intergovernmental Panel on Climate Change (IPCC) assessment reports. We recommend the implementation of a universal and transparent monitoring strategy of sea turtle fibropapillomatosis in sentinel bays, under the governance of the World Organisation for Animal Health.

Epidemiology of marine turtle fibropapillomatosis and tumour-associated chelonid alphaherpesvirus 5 (ChHV5; Scutavirus chelonidalpha5) in North-Western Mexico: a scoping review implementing the one health approach

Fibropapillomatosis (FP) - tumour-associated chelonid alphaherpesvirus 5 (ChHV5; Scutavirus chelonidalpha5) - is a disease that affect marine turtles around the world, and characterized by the formation of cutaneous tumours that can appear anywhere on the body. We carried out a thorough literature search (from 1990 to 2024) in the feeding sites of North-western Mexico, a region that hosts important habitats for feeding, development, and reproduction for five of the seven existing sea turtle species. We found 18 reports recording a total of 32 cases of FP and/or ChHV5/Scutavirus chelonidalpha5 in coastal and insular areas of North-western Mexico. Baja California Sur resulted with the highest number of cases (75%). While the first case of ChHV5/Scutavirus chelonidalpha5 infection was reported in 2004, the presence of FP tumours was reported in 2014 and became more frequent between 2019 and 2024. The affected species were black, Chelonia mydas (50%), olive ridley, Lepidochelys olivacea (46.8%) and loggerhead turtles, Caretta caretta (3.2%). Tumours occurred mainly in anterior flippers (46.1%) and neck (22.5%), and most had a nodular and verrucous appearance with a rough surface. In the study region, there is a potential sign of the emergence of the ChHV5/Scutavirus chelonidalpha5 infections and FP disease during the last 20 years, with a rapid increase during the last 10 years. As long as infections by ChHV5/Scutavirus chelonidalpha5 and the prevalence of the FP disease may be potentially influenced by anthropogenic activities, a One Health approach is needed to understand and improve sea turtles’ health.

Long‐term (29‐year) spatiotemporal patterns of sea turtle deaths in the southern Gulf of Mexico

Abstract Sea turtles are key imperilled species that interact with numerous threats in their critical in‐water and inland habitats, which they occupy along their complex life cycle. Therefore, analysing these interactions is essential for adapting ongoing conservation and management actions. The long‐term recording of stranded sea turtle individuals and the potential causes of death in their breeding habitats is crucial for defining and adapting conservation actions. Twenty‐nine years of sea turtle stranding and mortality data (1992–2019) at nesting beaches in Campeche, Mexico, were analysed to describe their spatiotemporal patterns per species and possible causes of death. The most impacted species was the hawksbill turtle, followed by green and Kemp's ridley individuals. The most frequent probable causes of death in this region were bycatch, seismic surveys, vehicle strikes and slaughter at nesting beaches. Both immature and breeding individuals were stranded, mostly the former, and the most frequent months were in the summer (June–August). This study establishes a historic reference baseline for the spatiotemporal mortality patterns of imperilled sea turtle species in the southeastern Gulf of Mexico. It shows their interactions with anthropogenic activities and the circumstances jeopardizing their population recovery. It also points out management and conservation actions to implement to improve their long‐term viability in the context of the operationalization of their key attributes and interactions with their seascapes.

Status and impacts to sea turtles in Vietnam

Sea turtles face a great danger of extinction because of human impacts, and the number of turtle occurrence is decreasing. By interviewing fishermen, coastal residents and authorities combined with field surveys in some places where turtles regularly lay eggs, such as Con Dao and Ninh Thuan, the results show that 05 species of sea turtles were found in Vietnam: The Green (Chelonia mydas), Hawksbill (Eretmochelys imbricata), Olive Ridley (Lepidochelys olivacea), Loggerhead (Caretta caretta) and Leatherback (Dermochelys coriacea). Among them, Green turtles are the most abundant and distributed in all surveyed localities; Hawksbill and Olive Ridley were smaller in number; and Loggerhead and Leatherback were the two species with the least number. Only 03 species remaining to breed on the beaches: Green, Olive Ridley, and Leatherback. The Hawksbill turtles used to lay eggs in the past but have been no longer recorded. Con Dao is a home for the largest number of breeding Green turtles. The reasons for the decline of turtles in Vietnam were the collection of eggs and nesting turtles, fisheries bycatch, development of coastal infrastructure and waste pollution, habitat degradation, and illegal trade in sea turtle products.

Baseline Skin Microbiota of the Leatherback Sea Turtle.

The integumentary system of the leatherback sea turtle (Dermochelys coriacea) is the most visible and defining difference of the species, with its smooth and waxy carapace and finely scaled skin, distinguishing it from the other six sea turtle species. The skin is the body's largest organ and serves as a primary defense against the outside world and is thus essential to health. To date, we have begun to understand that the microorganisms located on the skin aid in these functions. However, many host-microbial interactions are not yet fully defined or understood. Prior to uncovering these crucial host-microbial interactions, we must first understand the communities of microorganisms present and how they differ through life-stage classes and across the body. Here, we present a comprehensive bacterial microbial profile on the skin of leatherbacks. Using next-generation sequencing (NGS), we identified the major groups of bacteria on the skin of neonates at emergence, neonates at 3-4 weeks of age (i.e., post-hatchlings), and nesting females. These data show that the predominant bacteria on the skin of the leatherback are different at each life-stage class sampled. This suggests that there is a shift in the microbial communities of the skin associated with life-stage class or even possibly age. We also found that different sample locations on the nesting female (i.e., carapace and front appendages = flipper) have significantly different communities of bacteria present. This is likely due to differences in the microhabitats of these anatomic locations and future studies should explore if this variation also holds true for neonates. These data define baseline skin microbiota on the leatherback and can serve as a foundation for additional work to broaden our understanding of the leatherbacks' host-microbial interactions, the impacts of environmental changes or stressors over time, and even the pathogenicity of disease processes.

Sea turtle strandings in the temperate Southwest Atlantic: Analysis of drivers and potential causes

Abstract Marine megafauna are subject to several threats due to the increasing exploitation of marine ecosystems. Mortality is frequently evidenced by the occurrence of stranded individuals in coastal zones; however, conclusive identification of its drivers and causes is challenging. In this study, we explore the hypothesis that bycatch in trawling is one of the anthropic drivers of sea turtle strandings in the temperate Southwest (SW) Atlantic, where green (Chelonia mydas), loggerhead (Caretta caretta) and leatherback (Dermochelys coriacea) turtles forage seasonally. Beach survey data during March, April and May from 2014 to 2018 were used to characterize strandings and relate their spatio‐temporal distribution to physical and anthropic variables. Loggerhead (47.4%) and leatherback turtles (49.3%) were the most common stranded species, whereas green turtles were recorded only occasionally (3.3%). Based on the size distribution, strandings reflected both juvenile and adult mortality, with variations between species. Generalized linear models showed that sea turtle strandings were influenced by winds and sea surface temperature, while there was no evidence of a relationship with fishing effort. Further studies should assess drowning due to bycatch as a cause of turtle death, since interaction with fisheries is commonly reported in the area and drowned animals may or may not wash ashore. This study raises awareness and assesses, for the first time, the mortality of threatened sea turtle species in a poorly known region of its distribution.

Carapace Scute Variations of the Olive Ridley Sea Turtle (<i>Lepidochelys olivacea</i>): Polymerization as an Evolutionary Trend

The carapace scute pattern is an important morphological feature of turtles that, along with the phylogenetic stability, has a high level of intraspecific variability. The olive ridley sea turtle (Lepidochelys olivacea; Cheloniidae) demonstrates extreme instability of pholidosis, and the aim of our study is to identify the range of the carapace scute variations in this species. We studied 655 L. olivacea hatchlings from nine natural clutches on the Southern coast of Sri Lanka and identified 120 different patterns of carapace scutes. The vertebral and pleural scutes were the most variable, ranging in number from four or five to ten. Five pairs of pleural scutes, a normal condition for some species of sea turtles, were found in only 11.9% of individuals. The hatchlings with six and seven scutes in the vertebral and pleural series were the most numerous. 13 pairs of marginal scutes were the stable norm in 92.7% of individuals. Newborn turtles with symmetrical scute patterns predominated (60.9%). Comparison of the pholidosis variability in hatchlings from different clutches revealed the presence of specific scute patterns. We assume that the clutch differences are more related to the genetic characteristics of the breeding turtles than to the influence of environmental factors. The unique variable pholidosis of L. olivacea demonstrates a trend toward scute polymerization, a rare phenomenon in turtle evolution.

Histopathological findings in stranded Caretta caretta (Linnaeus, 1758) on the Paraná coast, Southern Brazil

Caretta caretta, one of the five sea turtle species in Brazil, is currently listed as globally endangered. While health assessments are crucial for monitoring population status, they are infrequent and lack systematic implementation. Evaluating the health condition of sea turtles can occur through examinations of both live and deceased animals. Carcasses play a pivotal role in identifying diseases and potential threats impacting the species. Therefore, this study presents the histopathological findings from 20 dead stranded C. caretta along the Paraná coast between 2015 and 2021. All individuals underwent measurements, and necropsies were conducted. The mean curved carapace length (cm) was 67.3 ± 6.9 (49.4 – 81.5). Body condition was classified as good in 13 animals, fair in four, poor in two, and undetermined in one. Fourteen females, four males, and two undetermined sexes were registered, with a mean age of 15.8 ± 3,89 (ranging from 9 – 24) years. Evidence of anthropogenic interaction (10 bycatch interactions, 6 marine debris, 2 oil interactions combined with marine debris) was noted in 80.0% of the animals. Histological changes primarily affected the liver, lungs, spleen, and kidneys, with prominent alterations such as inflammatory infiltrate (interstitial pneumonia, heterophilic splenitis, nephritis, endocarditis), congestion, and hepatic and renal hydropic degeneration. This study significantly contributes to our understanding of pathological findings in stranded wild C. caretta on the Paraná coast, offering valuable insights into the health of these animals and aiding in the conservation efforts to protect their populations.

Habitat use of loggerhead (Caretta caretta) and green (Chelonia mydas) turtles at the northern limit of their distribution range of the Northwest Pacific Ocean.

Verifying habitats, including the foraging and nesting areas for sea turtles, enables an understanding of their spatial ecology and successful planning of their conservation and management strategies. Recently, the observation frequency and bycatch of loggerhead (Caretta caretta) and green (Chelonia mydas) turtles have increased in the northern limit of their distribution range, in the northern part of the East China Sea and East (Japan) Sea. We conducted satellite tracking to investigate the habitat use of seven loggerhead and eight green turtles from June 2016 to August 2022 in this area, where little is known about their spatial ecology. We applied a 50 percent volume contour method to determine their main foraging areas and analyzed 6 environmental variables to characterize their habitats. Loggerhead turtles mainly stayed in and used the East China Sea as a foraging area during the tracking period, while two individuals among them also used the East Sea as a seasonal foraging area. Most green turtles also used the East China Sea as a foraging area, near South Korea and Japan, with one individual among them using the lower area of the East Sea as a seasonal foraging area. Notably, one green turtle traveled to Hainan Island in the South China Sea, a historical nesting area. Our results showed that the two sea turtle species included the East Sea as a seasonal foraging area, possibly owing to the abundance of food sources available, despite its relatively lower sea temperature. Considering that loggerhead and green sea turtles were observed using the northern part of the East China Sea and East Sea more frequently than previously known and that the sea temperature gradually increases due to climate change, conservation and management activities are required for sea turtles in these areas.

Critical areas for sea turtles in Northeast Brazil: a participatory approach for a data-poor context.

Fishing is one of the main threats to sea turtles due to the risk of entanglement in lost nets, vessel collision and mortality due to incidental catches. In Brazil, most of the studies regarding fishing interactions with sea turtles are focused on pelagic longline fisheries in the South and Southeast regions. However, their main reproductive areas in Southwest Atlantic RMU occur in Northeast Brazil, which overlaps small-scale coastal gillnet fisheries. Here, we aimed to use ethnobiology and participatory approaches as simple and cost-effective methods to identify areas for sea turtle conservation where impacts from small-scale fisheries are most likely. Expert captains were trained to recording sea turtle sightings during navigations from the landing port to the fishing grounds, informing their folk nomenclatures. By interpolation of environmental data (chlorophyll and bathymetry) and ecological data, we predicted habitats of 3,459.96 km² for Caretta caretta, Chelonia mydas, and Eretmochelys imbricata and fishing zones of 1,087 km² for management in 20 m and 50 m depths. Our results contributes to ongoing discussions of bycatch mitigation for sea turtle species and identification of habitats. We highlights the importance of considering particularities of overlapped areas in marine spatial planning and co-management arrangements.

Thermal vulnerability of sea turtle foraging grounds around the globe

Anticipating and mitigating the impacts of climate change on biodiversity requires a comprehensive understanding on key habitats utilized by species. Yet, such information for high mobile marine megafauna species remains limited. Here, we compile a global database comprising published satellite tracking data (n = 1035 individuals) to spatially delineate foraging grounds for seven sea turtle species and assess their thermal stability. We identified 133 foraging areas distributed around the globe, of which only 2% of the total surface is enclosed within an existing protected area. One-third of the total coverage of foraging hotspots is situated in high seas, where conservation focus is often neglected. Our analyses revealed that more than two-thirds of these vital marine habitats will experience new sea surface temperature (SST) conditions by 2100, exposing sea turtles to potential thermal risks. Our findings underline the importance of global ocean conservation efforts, which can meet climate challenges even in remote environments.

Novel Microsatellite Tags Hold Promise for Illuminating the Lost Years in Four Sea Turtle Species.

After hatching, sea turtles leave the nest and disperse into the ocean. Many years later, they return to their natal coastlines. The period between their leaving and their returning to natal areas, known as the "Lost Years", is poorly understood. Satellite tracking studies aimed at studying the "Lost Years" are challenging due to the small size and prolonged dispersal phases of young individuals. Here, we summarize preliminary findings about the performance of prototype microsatellite tags deployed over a three-year period on 160 neonate to small juvenile sea turtles from four species released in the North Atlantic Ocean. We provide an overview of results analyzing tag performance with metrics to investigate transmission characteristics and causes of tag failure. Our results reveal that, despite certain unfavorable transmission features, overall tag performance was satisfactory. However, most track durations were shorter than those observed on individuals of similar size in other studies and did not allow for detailed analyses of trajectories and turtle behavior. Our study further suggests that tracking durations are correlated with the targeted species, highlighting a lack of robustness against some neritic behaviors. Unprecedented diving data obtained for neonate sea turtles in this study suggest that the vertical behaviors of early juveniles are already too strenuous for these miniaturized tags. Our findings will help to inform the biologging research community, showcasing recent technological advances for the species and life stages within our study.

A Systematic Review of Population Monitoring Studies of Sea Turtles and Its Application to Conservation

Sea turtles are keystone species in marine environments due to their essential role as seagrass grazers and population regulation of jellyfish and sponges in coral reefs. However, due to their predominant presence in coastal areas, sea turtle populations face significant threats due to the impact of human activities. In this systematic review, 655 peer-reviewed publications were analyzed to assess the extent of population monitoring for all seven sea turtle species. The analyses revealed that, although population monitoring studies have increased for sea turtles in the past four decades, these have been biased towards certain species and oceanic regions. Furthermore, sea turtle population monitoring has been undertaken primarily using field-based methods, with satellite tracking and nest surveys being the most commonly used methods; however, the implementation of genetic methods for population monitoring has increased since the 2000s. Direct conservation recommendations from this study include the urgent need to establish population monitoring studies in the Critically Endangered Kemp’s ridley and hawksbill and the Data Deficient flatback. Furthermore, population monitoring programs should be implemented in Southeast Asia and Northern and Central Africa, where knowledge on sea turtle populations is still limited. Finally, due to the long-distance movements of sea turtles, we also advocate for international cooperation and collaboration of local communities to protect these ecologically important and iconic marine species.

Overview of the population genetics and connectivity of sea turtles in the East Asia Region and their conservation implications

Understanding the current status and recent development of the population genetics and connectivity of sea turtles is crucial for effective conservation management of the species. Five sea turtle species, green turtle (Chelonia mydas), loggerhead turtle (Caretta caretta), hawksbill turtle (Eretmochelys imbricata), olive ridley turtle (Lepidochelys olivacea) and leatherback turtle (Dermochelys coriacea), are recorded in the East Asia Region situated in the western side of the North Pacific Ocean. We compiled information from 35 published genetic studies on the five sea turtle species, with a focus on green turtle and loggerhead turtle, which are the most studied species (in 30 studies) in view of their commonness and occurrence of nesting populations. We provided an overview of the key methods and findings of these previous studies, addressing two main objectives on genetic structure of the rookeries and their differences compared to other populations, and connectivity of the rookeries and foraging aggregations. By identifying information gaps and conservation needs, we discussed future developments for sea turtle genetic studies and conservation implications in the region.

Small-scale movements and site fidelity of two sympatric sea turtle species at a remote atoll

Understanding natural movement patterns and ecological roles of marine megafauna is a research priority best studied in areas with minimal human impact. The spatial distribution patterns specifically for immature turtles at foraging grounds have been highlighted as a research gap for effective management and conservation strategies for sea turtle populations. Capture–mark–recapture (CMR) records (n = 2287) of 1672 immature green (Chelonia mydas) (n = 1158) and hawksbill turtles (Eretmochelys imbricata) (n = 514) from a long-term (1981–2021) in-water CMR program at Aldabra Atoll, Seychelles, were analyzed for 10 sites (0.35–25 km apart). Site fidelity was not correlated with either season or turtle size. Green turtles had lower site fidelity than hawksbill turtles. Green turtles showed avoidance (i.e., opposite of fidelity) of three sites, while hawksbill turtles displayed high fidelity to two sites. Sites displaying non-random behavior (avoidance and/or fidelity) did not share the same benthic habitat types. Results indicate that fidelity can be detected at a fine scale with CMR, but that further exploration into the habitat characteristics of the sites and the ecological roles of both species at the atoll is needed.

Sea turtle density surface models along the United States Atlantic coast

Spatially explicit estimates of marine species distribution and abundance are required to quantify potential impacts from human activities such as military training and testing, fisheries interactions, and offshore energy development. There are 4 protected species of sea turtle (loggerhead, green, Kemp’s ridley, and leatherback) commonly found along the east coast of the USA, our study area, and which require impact assessments. Data from 7 different survey organizations were used to create density surface models for the 4 sea turtle species utilizing 1.2 million km of line-transect surveys. A substantial portion (29.7%) of available sightings were not identified to the species level. Not including these sightings would underestimate density, so a conditional random forest model was used to assign unidentified sightings to species. Higher densities of loggerhead, green, and Kemp’s ridley sea turtles were predicted south of the Outer Banks in cool months, transitioning northwards in late spring to occupy seasonal neritic habitats. The highest leatherback densities were predicted off the coasts of Georgia and Florida. Leatherbacks were also predicted throughout offshore areas. The predicted distribution patterns generally matched satellite tracking and strandings data, indicating the models reproduced established seasonal movements. Surveys rarely detect sea turtles smaller than 40 cm, so these age classes are not represented. The models are the first for the study area to apply availability bias estimates developed in or near the study area and attempt to classify unidentified sightings to the species level, providing an updated, critical tool for conservation management along the eastern seaboard.

Connectivity between sea turtles off Jeju Island on the Korean Peninsula, and other populations in the western Pacific

The northwestern Pacific region is an important habitat for sea turtles, hosting five species out of seven. There is still limited information available about the sea turtle aggregations around the Korean Peninsula, which is the northern boundary for many sea turtle species in the western Pacific area. The present study aims to investigate the migratory route of sea turtles visiting Jeju Island. Five species of sea turtles were identified from by-catch and stranding data between 2013 and 2022 on Jeju Island in Korea: green (Chelonia mydas; 24 individuals), loggerhead (Caretta caretta; 9), hawksbill (Eretmochelys imbricata; 2), olive ridley (Lepidochelys olivacea; 2), and leatherback (Dermochelys coriacea; 1). Mixed stock analysis using mitochondrial DNA haplotypes revealed that Jeju green turtles primarily originate from the rookeries of the Japanese Archipelago. This connectivity between two regions was also supported by the similar genetic composition of loggerhead turtles. Similarly, satellite tracking data showed that several green turtles originating from Jeju Island migrated to waters near the Ryukyu Archipelago in Japan. Nevertheless, about 60% of the tracked green turtles stayed near Jeju Island, with most overwintering there, indicating the long residency in Jeju Island. This study also provides the genetic sequences of other three species including new orphan haplotypes of hawksbill and olive ridley turtles. Our findings suggest that Jeju Island serves as a stable foraging habitat and provide insight into understanding the habitat range of sea turtles in the western Pacific.

Trophic ecology of sympatric sea turtles in the tropical Atlantic coast of Brazil

The Tropical Atlantic coast of Brazil is a hotspot area for multiple sea turtle species at all life stages. The multiple nearshore reefs and beaches, oceanic islands, and the only atoll in the south Atlantic Ocean, are suitable for year-round foraging, migration corridors, and nesting activities of five sea turtle species. Still, relatively few studies have assessed trophic niche among sympatric sea turtles which can provide a better understanding of how closely related species compete/partition the available resources. Using multiple biogeochemical tracers (i.e., nitrogen (δ15N) and carbon (δ13C) stable isotopes, and mercury (Hg)), we disentangled the trophic niches of four sea turtle species – the green turtle (Chelonia mydas), the loggerhead turtle (Caretta), the hawksbill turtle (Eretmochelys imbricata), and the olive ridley turtle (Lepidochelys olivacea) – co-occurring in nesting and foraging habitats along the northeastern coast of Brazil. We found interspecific differences in isotopic and contamination niches, as well as intraspecific niche variation associated with life stage. Differences in the estimation niche models associated to life-stage in C. caretta support the notion of ontogenetic shift in habitat and diet composition previously reported for this species. Oceanic habitat signatures were observed in juvenile green turtles and adult olive turtles, while nearshore habitat signatures were observed in adult hawksbill turtles.