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The current climate warming is a challenge to biodiversity that could surpass the adaptation capacity of some species. Hence, understanding the means by which populations undergo an increase in their thermal tolerance is critical to assess how they could adapt to climate warming. Specifically, sea turtle populations could respond to increasing temperatures by (1) colonizing new nesting areas, (2) nesting during cooler times of the year, and/or (3) by increasing their thermal tolerance. Differences in thermal tolerance of clutches laid by different females would indicate that populations have the potential to adapt by natural selection. Here, we used exhaustive information on nest temperatures and hatching success of leatherback turtle (Dermochelys coriacea) clutches over 14 years to assess the occurrence of individual variability in thermal tolerance among females. We found an effect of temperature, year, and the interaction between female identity and nest temperature on hatching success, indicating that clutches laid by different females exhibited different levels of vulnerability to high temperatures. If thermal tolerance is a heritable trait, individuals with higher thermal tolerances could have greater chances of passing their genes to following generations, increasing their frequency in the population. However, the high rate of failure of clutches at temperatures above 32°C suggests that leatherback turtles are already experiencing extreme heat stress. A proper understanding of mechanisms of adaptation in populations to counteract changes in climate could greatly contribute to future conservation of endangered populations in a rapidly changing world. [ABSTRACT FROM AUTHOR]

Northwest Atlantic leatherback (Dermochelys coriacea) sea turtle populations are endangered and have low hatching success compared to other sea turtles. Hatchling survival is an important element of their conservation. This longitudinal study assessed developmental phase and pathology of leatherback embryos and hatchlings at Sandy Point National Wildlife Refuge (SPNWR) on St. Croix, US Virgin Islands, in 2019 to identify patterns in mortality and lesions across a nesting season, and to make regional comparisons. Hatching and emergence success averaged 63.6% and 56.6%, respectively, and both differed significantly by month. 'Breakout' analysis was conducted on 41 nests and showed a preponderance of unhatched eggs lacking grossly evident embryological development (52%). Necropsies were performed on 79 unhatched and dead in nest individuals from 34 nests, and most (58%) had lesions including inflammation associated with microorganisms (34%), renal mineralization (15%), mild multifocal skeletal muscle degeneration and necrosis (5%), and anatomic malformations (4%). Inflammatory lesions included chorioallantoitis, esophagitis, stomatitis, dermatitis, gastritis, and yolk sacculitis. These were associated with bacteria (n = 13), fungi (n = 4), or both (n = 7). Sex was determined histologically and was predominantly female (90%) with no males identified in nests laid after 3 April 2019. Although hatching success was higher in in situ relative to relocated nests, embryological development and lesion patterns were similar in both groups. Patterns of lesions observed in leatherback embryos and hatchlings did not differ across the season and are comparable to other Caribbean nesting sites. Future studies pairing 'breakout' and pathological analyses with assessments of potentially influential environmental and/or maternal factors could help develop targeted strategies for improving hatchling production. [ABSTRACT FROM AUTHOR]

This short communication reports an observation of a leatherback turtle Dermochelys coriacea in the İstanbul Strait (Bosphorus), Marmara Sea, on 9 July 2024. Leatherback turtles are occasionally reported in the Aegean and Mediterranean Seas of Türkiye. This is the northernmost record of the leatherback turtle in the Mediterranean Basin. As the importance of citizen science becomes more apparent and public awareness grows, access to observational information such as this will increase through digital technologies. [ABSTRACT FROM AUTHOR]

OBJECTIVE Determine the hemolytic effect of an 18-µm microaggregate blood filter during in vitro sea turtle whole blood transfusions as well as describe the average diameter of leatherback (Dermochelys coriacea) and Kemp’s ridley sea turtle (Lepidochelys kempii) RBCs. ANIMALS 5 green (Chelonia mydas), 5 loggerhead (Caretta caretta), and 5 Kemp’s ridley sea turtles (total n = 15). METHODS Heparinized sea turtle blood was infused at 60 mL/h through a microbore extension set without and then with a postsyringe, inline 18-µm microaggregate blood filter. Pre- and postfiltration PCV, Hct, total solids, sodium, chloride, potassium, glucose, and free plasma hemoglobin concentrations were measured. With the use of light microscopy and archived blood smears, the maximum and minimum diameter of 20 RBCs from each of the 5 leatherback and 5 Kemp’s ridley sea turtles were measured with a calibrated ocular micrometer using 400X magnification. RESULTS There were no significant differences between pre- and postfiltration samples for Hct, total solids, sodium, chloride, potassium, glucose, and free plasma hemoglobin concentrations; however, there was a significant median postfiltration decrease in PCV of approximately 4%, representing a 13% decrease of the total RBCs transfused. Average maximum diameters for leatherback and Kemp’s ridley sea turtle RBCs were 19.7 and 16.1 µm, respectively. CLINICAL RELEVANCE Although the 18-µm microaggregate blood filter does not hemolyze transfused sea turtle RBCs and is likely safe for in vivo blood transfusions, the filter’s pores may retain a small proportion of infused RBCs given their diameter. [ABSTRACT FROM AUTHOR]

For the Western Indian Ocean region, there is a significant knowledge gap regarding marine turtle nesting on the continental coast of East Africa. Here we present results from a long-term (2000–2020) community-based monitoring programme in and around Watamu Marine National Park, Kenya, covering 30 km of coastline (c. 6% of the national total). Conservation actions effectively protected nesting turtles and resulted in a near-total cessation of illegal egg harvesting in Watamu Marine National Park. Collected data indicate this is an important marine turtle nesting index site in Kenya and the wider region. Green turtle Chelonia mydas nests were most common (95%), followed by olive ridley turtles Lepidochelys olivacea (4%), with occasional nests of hawksbill Eretmochelys imbricata and leatherback turtles Dermochelys coriacea. Clutches per season increased significantly over the 20-year monitoring period for green turtles (50%) and showed a positive trend for olive ridley turtles. Watamu remains an area at risk from human pressures such as coastal development. Clutch distribution along the Watamu Marine National Park beach has shifted over time, probably because of coastal development and disturbance. Illegal take of adults and eggs continues in areas north and south of the Watamu Marine National Park, possibly slowing rates of recovery. Clutches deemed at risk were moved to a safe location within the National Park, and hatching success was high. Continued conservation efforts, including wider engagement with stakeholders to reduce human pressures, are needed to ensure the perpetuation of this nesting site. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Fungal infections were histologically confirmed in 20 stranded sea turtles, including 18 Kemp's ridley turtles (Lepidochelys kempii), 1 green turtle (Chelonia mydas), and 1 leatherback turtle (Dermochelys coriacea). Infection was detected antemortem in six cases. Gross external findings in live turtles included carapace lesions (n = 3) and dermatitis (n = 1). Radiographs revealed evidence of pneumonia in 18 animals. Bronchoscopy detected excessive fluid, mucus, clotted blood, or caseous material within the bronchi and lungs of three turtles. At necropsy, the most common gross lesions were pulmonary granulomas, consolidation, and/or hemorrhage (n = 18), and the most common histologic lesion was severe heterophilic-to-granulomatous pneumonia (n = 18). Nine animals had fungal infection at sites outside of the lung. The most commonly identified genera were Purpureocillium, Beauveria, and Fusarium. Other isolates included Metarhizium sp., Trichoderma sp., Clavispora lusitaniae (Candida lusitaniae), Leptospherulina sp., Penicillium chrysogenum, Mucor sp., and Aspergillus section Nigri. Antifungal susceptibility performed for 10 isolates indicated minimum inhibitory concentrations (milligrams per liter) for fluconazole ranging from 8 to >64, often >32; itraconazole from 0.06 to 16, often ≤1; voriconazole from 0.06 to 2, often ≤0.5; and terbinafine from 0.06 to >2, often ≤2. These data indicate that fluconazole resistance is common among the fungi that cause infection in sea turtles. Based on susceptibility data, itraconazole, voriconazole, or terbinafine may be appropriate for treatment of such infections, but additional clinical research is needed. Results of this study indicate that fungal infections can be difficult to diagnose antemortem in sea turtles, and more aggressive methods of diagnosis, such as lung biopsy, may be indicated for suspected cases. [ABSTRACT FROM AUTHOR]

Western Pacific leatherback sea turtles (Dermochelys coriacea) are a priority bycatch mitigation concern due to the projected extinction of the population before the end of the 21st century. The species regularly occurs as bycatch in gillnet and surface longline fisheries. Here, we explore the potential for dynamic ocean management in an emerging hotspot of leatherback sea turtle bycatch in the New Zealand pelagic longline fishery. We compared spatial areas of different sizes built from single oceanographic covariates as well as built from a composite risk surface developed through ensemble random forests. We found that, individually, the Okubo-Weiss parameter, sea surface temperature (SST) anomaly, SST, moon phase, and distance to the SST front were important oceanographic covariates for leatherback sea turtle bycatch. However, the spatial areas built from the composite risk surface were the most effective at discriminating sets with and without bycatch across a range of risk cutoffs. When we also considered implementation metrics of spatial area and coherence as part of performance, the area derived from the composite risk surface with a risk of interaction per set greater than 52% performed best. This spatial area was ephemeral, occurring 1 or 2 weeks each year, and localized, occurring along the north coast of East Cape in the North Island of New Zealand. The apparent presence of discrete spatial areas with elevated risk may be useful to inform future management in the area. Considering implementation metrics in defining utility was useful for identifying tradeoffs between the total size and the underlying covariates delineating a spatial area. As such, we recommend these types of metrics to be included when designing spatial bycatch mitigation strategies elsewhere. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Leatherback sea turtles (Dermochelys coriacea) migrate along the east coast of the United States, traversing the South and Mid-Atlantic Bights (SAB and MAB) while traveling to and from well-known northern foraging areas off Southern New England (SNE) and Nova Scotia. However, there is limited information on leatherback movement behavior in these regions. To identify leatherback movement patterns, we fit hidden Markov models (HMMs) to satellite transmitter data from 52 leatherbacks tagged between 2017 and 2022 off the coasts of Massachusetts and North Carolina to estimate locations of area restricted searching (ARS) and transient behaviors. Depth-temperature profiles were then paired to locations associated with ARS behavior to understand the vertical use of the water column. We observed leatherbacks displaying ARS behavior in SNE as expected, but also in the MAB and SAB. The HMM results indicated that leatherbacks were primarily foraging in SNE between Nantucket and Long Island Sound and depth-temperature plots from ARS behavior on Nantucket Shoals implied turtles foraging throughout the entire water column. In the MAB, ARS behavior was concentrated between Cape Hatteras, North Carolina, and the mouth of Delaware Bay during the summer. Turtles were closely associated with a well-defined thermocline, but still appeared to dive to deeper cooler waters, which may be a sign of thermoregulatory behavior. There was evidence of foraging in the SAB along the coast as well as along the continental shelf edge. The ARS behavior we documented within the MAB and SAB is the first published empirical evidence that both areas may be important foraging grounds. Our results lay a path for future research to understand how leatherbacks use these areas and the potential anthropogenic threats encountered while moving through these regions. [ABSTRACT FROM AUTHOR]

Sea turtles face a risk of extinction due to climate change causing warming of nests, which may increase both sex ratio skews, with fewer males being produced, and embryo mortality in nests. In theory, these threats could be mitigated by turtles switching their nest sites to cooler locations on beaches. We assessed nest positioning for green turtles, Chelonia mydas , in the Chagos Archipelago, a major nesting site in the Indian Ocean, and showed that nests were generally in vegetation at the back of the beach, where the risk of sea water inundation was lowest. The relatively few nests on the open beach were on average close to the vegetation. Sand temperatures at nest depths were similar across three beach zones (open sand, edge of vegetation, within the vegetation). Nest positioning was reviewed for 51 studies at 53 sites (including the current study) across the globe and across seven species: green turtles, hawksbills, Eretmochelys imbricata , loggerheads, Caretta caretta , leatherbacks, Dermochelys coriacea , olive ridleys, Lepidochelys olivacea , Kemp's ridleys, Lepidochelys kempii , and flatbacks, Natator depressus. Both in the Chagos Archipelago and across the globe studies show turtles generally tend to crawl a sufficient distance to minimize sea water overwash of nests, which can kill embryos. Hence maximizing embryo survival, rather than considerations of hatchling sex ratios, seems to be the main driver for nest positioning and so we conclude that sea turtles are, generally, unlikely to switch to select cooler beach sites to mitigate climate warming. • Most green turtle nests at an Indian Ocean rookery were in the vegetated zone. • Nests were positioned 0.14–2.44 m above the mean high water height. • Impenetrable vegetation led to long circuitous crawls to locate suitable nest sites. • The key factor in nest site selection is likely hatchling survival not sex-ratios. • Turtles are unlikely to shift sites on beaches to reduce impacts of climate change. [ABSTRACT FROM AUTHOR]

The article reviews the National Wildlife Federation's (NWF) series of reptile stamps issued from 1941 to 1996, highlighting the various species depicted and the history behind these stamps. Topics include the diversity of reptiles featured, the involvement of renowned wildlife artists, and the evolution of stamp designs over time.

Beach monitoring programmes along the Brazilian coast in recent years have provided stranding data which can be analysed to show the effects of human impacts on sea turtle populations. In Brazil, the five species recorded are threatened with extinction. In this study, data from strandings of sea turtles on the northern coast of the State of São Paulo, Brazil, over six years (2015–2021), were used to evaluate whether human activities are associated with impacts on the populations and to analyse the effects of seasonality on abundance. There were 6411 strandings of sea turtles, the majority being Chelonia mydas, followed by Caretta caretta, Lepidochelys olivacea, Eretmochelys imbricata and Dermochelys coriacea. Strandings occurred mainly during winter and spring. Where it was possible to determine the cause of death of an individual, there were several associations with anthropogenic factors, mainly solid waste, fishing gear, collisions with vessels, injuries and dredging. The high incidence of strandings of sea turtles on the Brazilian coast, mostly juveniles, and the great impact of anthropogenic factors in the causa mortis indicate the need to adopt ocean education strategies and public policies that can establish effective management and conservation plans of marine ecosystems. [ABSTRACT FROM AUTHOR]

Assessing abundance and monitoring ecology and population trends are of critical importance for animal species of conservation concern. For sea turtles, annual nest counts represent the most common method of estimating population size. However, to develop a better understanding of population trends, these data need to be complemented by other reproductive parameters, which are lacking for many nesting populations across central Africa.To this end, an intensive capture–mark–recapture programme was conducted spanning 21 years (1997–2018) in the most important nesting sites on the Atlantic coast of central Africa (Gabon and Congo) for leatherback (Dermochelys coriacea) and olive ridley (Lepidochelys olivacea) sea turtles.A total of 18,105 encounters of 14,109 D. coriacea individuals and 2678 encounters of 2427 L. olivacea individuals were recorded. Biological and technical parameters such as clutch frequency, inter‐nesting interval, remigration interval, annual survival rate, somatic growth, size trends, tag loss and number of annual nesting females were estimated through a variety of methods and models.The study detected a decline in body size and low survival probability (not due to tag loss) in both species but no clear decline in estimated annual number of nesting females. High fidelity to nesting sites (<30 km for both species) implies that the current conservation strategy, protecting the main nesting areas, could be effective.We recommend that local conservation managers promote: (i) continued monitoring of the nesting activity of the two species through capture–mark–recapture programmes; (ii) continued nest counts at long‐term monitoring sites, which may also detect possible spatial shifts; and (iii) strengthening of cross‐border cooperation between Gabon and Republic of the Congo given the observed connectivity between nesting sites of the two countries. [ABSTRACT FROM AUTHOR]

Most of the information available on loggerhead turtles (Caretta caretta) and leatherback turtles (Dermochelys coriacea) for the southern coast of Portugal is based on stranding data, and to a less extent on telemetry data, with very little information derived from sightings of live animals.This work reports sightings data of loggerhead and leatherback turtles off the south coast of Portugal collected during dedicated surveys on board a research boat, from 2016 to 2022.The sightings data corrected for effort confirm the recurrent presence of loggerhead turtles in the study area, with a higher sightings rate in May and June. Conversely, leatherback turtles were only sporadically observed in some years.This study highlights the importance of the southern waters of Portugal for loggerhead turtles as a recurrent area used by individuals of this species, probably from different origins within the North Atlantic and the Mediterranean, in line with previous studies.The southern coast of Portugal, however, is heavily exploited by fisheries, and the main cause of death among sea turtles is bycatch. The results presented will therefore help inform future management measures aiming to reduce interactions with fisheries (e.g., limiting some fishing gears in the months with more sightings).Since the study area is probably used by loggerhead turtles from different Regional Management Units, the impacts of conservation measures imposed locally may also have beneficial effects at a regional scale. [ABSTRACT FROM AUTHOR]

Fisheries bycatch is considered the largest threat to sea turtle populations globally. However, it has been challenging to assess the impact of bycatch on sea turtles in some regions such as Northwest Africa (i.e. Cabo Verde, Guinea, Guinea–Bissau, Mauritania, Senegal, Sierra Leone and The Gambia) owing to large data gaps. This hampers effective management actions and interferes with conservation efforts in the region.Five sea turtle species occur in Northwest Africa (i.e. green turtle Chelonia mydas, hawksbill Eretmochelys imbricata, leatherback Dermochelys coriacea, loggerhead Caretta caretta and olive ridley Lepidochelys olivacea). The region has regionally and globally important sea turtle nesting and foraging habitats and is a global fishing hotspot, with high and increasing fishing pressure.Available information on sea turtle bycatch in Northwest Africa was compiled from peer‐reviewed and grey literature from 2010 onwards to determine the impact of artisanal and industrial fisheries (by gear type) on regional sea turtle populations and assess the level of threat to individual species.All sea turtle species occurring in the region are impacted by bycatch. Reports suggest that green turtles and loggerheads have the highest bycatch rates, probably owing to their regional abundance and widespread distribution. Some of the potentially highest reported global bycatch rates (14,000–90,000 turtles/year/country) are noted, particularly in gillnets, longlines and handlines. However, further research is needed to understand mortality levels from artisanal fisheries and assess the impact of trawl fisheries operating in the region. Additional sources of mortality include deliberate capture for consumption or trade.To strengthen regional sea turtle conservation and reduce sea turtle bycatch and mortality, urgent action is needed to implement and enforce national protection, establish a bycatch reduction framework (including gear modifications and spatio‐temporal closures), improve fisheries data collection and build capacity. [ABSTRACT FROM AUTHOR]

Sea turtles are threatened with extinction around the world and rely on sandy beaches for laying their eggs. To protect eggs and locate them for calculation of reproductive success, beach surveyors must find the exact placement of each clutch. Eggs may be buried up to one meter deep under a nest mound several square meters in area. To locate sea turtle eggs, beach surveyors might spend hours searching for these eggs hidden in the sand, especially for difficult-to-locate leatherback (Dermochelys coriacea) and green turtle (Chelonia mydas) eggs. Scent-detection dogs (Canis lupus familiaris) are a novel tool that could provide a means to more accurately identify nests and efficiently locate eggs that need assessment, protection, or relocation. We assessed the effectiveness and feasibility of using a detection dog to locate sea turtle eggs buried in beach sand as compared to the traditional method using human beach surveyors. The detection dog was significantly more accurate in detecting loggerhead sea turtle (Caretta caretta) eggs and more efficient (less time spent and fewer holes dug) in assisting with locating the eggs. This case study presents results on the performance of one detection dog only, and additional research is needed with multiple detection dogs and handlers. [ABSTRACT FROM AUTHOR]

Despite multiple studies examining the diving behavior of leatherback sea turtles (Dermochelys coriacea) at coarse resolution over broad distances, there is still a paucity of high‐resolution diving data collected in areas where foraging has been confirmed. Short‐term (~1–3 h) deployments of suction cup tags with time–depth recorders (TDRs) on 10 free‐swimming leatherback turtles in a foraging area off Nova Scotia, Canada during August and September (2007–2014), captured a total of 161 dives. High‐resolution (1–5 s sampling rate) dive profile data indicated variability in diving behavior between and within individuals. On average, turtles spent 55.7% of their time diving and 44.3% at the surface. Turtles generally performed short (mean duration = 250.4 s [SD = 47.9 s]) and shallow dives (mean depth = 24.3 m [SD = 5.8 m]). We recorded a mean dive descent rate of 0.32 m/s, which is faster than values recorded for leatherbacks in tropical waters. This may reflect differences in environment, behavioral mode (e.g., foraging vs. inter‐nesting), and body condition. Linear mixed‐effects models suggest a significant positive correlation between descent rate and mean depth, maximum depth, and integrated vertical bottom movement (IVBM). Turtles with faster descent rates dove deeper and increased their predicted foraging behavior (IVBM, or the sum of absolute differences in depth changes while at the bottom portion of their dives). Models additionally showed that dive time, bottom time, and IVBM were all positively correlated to the post‐dive surfacing. This suggests that turtles required more time at the surface to recover and/or handle prey following longer dives characterized by increased vertical movement at the bottom portion of the dive. Dives were complex; the application of standard dive type/shape analysis may be over‐simplified and inappropriate for leatherbacks foraging in these habitats. These results portray a novel and detailed look at the foraging dynamics of a diving marine reptile. [ABSTRACT FROM AUTHOR]

Plastic pollution has not raised much attention until the 2000s, despite being manufactured for about a century. It is now considered one of the most substantial environmental issues. Here we investigate the presence of plastic contamination in 34 stranded animals on the coast of French Guiana, South America. Here we present information highlighting the magnitude of plastic contamination in marine coastal and pelagic tropical marine vertebrates on the Equatorial Atlantic coast of South America. All four species studied here are protected and emblematic vertebrates of the region, with a fragile conservation status, including the olive ridley turtle Lepidochelys olivacea, the green turtle Chelonia mydas and the leatherback turtle Dermochelys coriacea, and a small cetacean, the Guiana dolphin Sotalia guianensis. Macroplastics (polypropylene, polyethylene, terephthalate, and polystyrene) were detected in four juvenile green turtles. Microplastics (polypropylene, polyethylene, terephthalate, polystyrene, nylon, acrylates, polycarbonates) were found in 13 individuals (two dolphins, six olive ridleys, four green turtles, and the leatherback turtle). The sampled species have different diets, distribution patterns, and ages, suggesting widespread plastic pollution. The study area is located far from the oceanic gyres. However, they are influenced by the North Brazilian Current, the Amazon River, and other rivers of the Guianas. [ABSTRACT FROM AUTHOR]

Australia's largest sea turtle is the leatherback (Dermochelys coriacea). Leatherbacks do not nest, or only rarely, in Australia, and hence receive relatively little research attention. Here we review the knowledge of leatherback turtle occurrence in south-east (SE) Australia, drawing on sightings information as well as satellite tracking data from turtles equipped at their nesting beaches in Indonesia, the Solomon Islands and Papua New Guinea that then travelled to Australia. These data reveal that SE Australia likely provides a globally important foraging area for this species. Sea turtle temperatures assigned to sightings of live leatherbacks, showed 95% were seen at SSTs ≥ 14 °C. Similar to other parts of the world, such as the North Atlantic, the 12–15 °C isotherms likely constrain the seasonal pole-wards migration of leatherbacks searching for their gelatinous prey. Climate warming is likely moving the foraging range of leatherbacks poleward. This study also highlights the vulnerability of this SE Australian population to anthropogenic threats. Of 605 sightings of leatherbacks, 11.6% were of dead individuals, generally washed ashore, in most cases likely after entanglement in fishing gear. [ABSTRACT FROM AUTHOR]

The St. Kitts Sea Turtle Monitoring Network (SKSTMN) began implementation of a leatherback sea turtle (Dermochelys coriacea) monitoring program in 2003 on the main leatherback nesting beaches on St. Kitts, Keys Beach, and North Friars Beach, West Indies. From March 2003 to July 2016, a total of 2,419 adult female leatherback emergence events were recorded and evaluated. A notable decrease in adult leatherback emergence activity was observed over the course of the study period. The nesting season was documented to range from February to August. April and May were typically the months with the highest frequency of nesting. The number of females individually identified (flipper tagging and/or passive integrated transponder) from 2004–2016 was 259, with a mean curved carapace length (CCL) (n = 720) of 153 cm and mean curved carapace width (CCW) (n = 719) of 113 cm. Remigration intervals ranged from 1–5 yr with a median of 2 yr. For nesting females in St. Kitts over the course of the study period, mean clutch frequency (with standard deviation [SD]) was 3 (SD 2.9) and during a reproductive season was 2.2 (SD 1.44). Mean total number of eggs laid per nest was 113 with mean number of yolked eggs being 83.5 and yolkless 29.3. The mean incubation period was 59.5 days overall (SD 3.5) with a hatch success overall of 16.75%. Relocated nests had significantly lower hatch success than in situ nests and poaching rates decreased over the course of this study. From 2006–2016, a total of 191 blood samples were collected from 118 individual animals. Hematological and plasma biochemical parameters are outlined and changes in values in individuals over the course of nesting seasons and association with remigration intervals are described. The goal of this study was to report on 14 years of leatherback monitoring and determine the baseline health profile of the nesting leatherback population in St. Kitts. [ABSTRACT FROM AUTHOR]

Simple Summary: Leatherback sea turtle (Dermochelys coriacea) populations are experiencing significant declines and are at risk of global extinction. Sustaining reproductive success is vital to the recovery of populations. This study quantified nests and egg production between 2015–2019 on Levera Beach, Grenada and explored the association of select environmental variables with leatherback sea turtle embryonic development and hatching success rates. Annual variation was observed for the number of eggs per nest and embryo and hatching success rates. Nest location on the beach was found to be an influencing factor and development and hatching success rates decreased when nest depths were relatively shallow and when there was higher frequency of eggs with microbial growth and inspissated yolk. Relatively high temperatures recorded in a subset of nests suggest hatchling sex ratios may be skewed towards females and that increased temperatures are a risk to hatchling survival. Histopathology identified bacterial bronchopneumonia as a likely cause of morbidity and mortality in hatchlings. These findings help guide conservation strategies to support leatherback sea turtle hatchling survival. Annual monitoring of leatherback sea turtle (Dermochelys coriacea) nesting grounds in Grenada, West Indies has identified relatively low hatch rates compared to worldwide trends. This study investigated the impact of selected environmental variables on leatherback sea turtle embryonic development and hatching success rates on Levera Beach in Grenada between 2015–2019. The mean number of nests per year and eggs per nest were 667.6 ± 361.6 and 80.7 ± 23.0 sd, respectively. Within excavated nests, 35.6% ± 22.0 sd of eggs successfully developed embryos and 30.6% ± 22.6 sd of eggs successfully hatched. The number of eggs per nest, along with embryo and hatching success rates, differed by nesting year. Embryo development success rate was associated with nest location, and both embryo development and hatching success rates were positively associated with nest depth and negatively associated with the percentage of eggs exhibiting microbial growth and with the presence of inspissated yolk. There was no embryo development or hatchling success association with month of the nesting season, distance from the high-water mark, distance from vegetation, nor maternal carapace length. The mean nest temperature was 31.7 °C ± 1.64 sd and mean temperatures during the middle third of egg incubation suggest clutches are highly skewed towards a preponderance of female hatchlings. Histopathologic findings in hatchling mortalities included severe, acute, multifocal, heterophilic bronchopneumonia with intralesional bacteria in 4/50 (8%) hatchlings. Data from this study guide conservation strategies by identifying risk factors and further avenues of research needed to support reproductive success of leatherback sea turtles in Grenada and the greater Caribbean region. [ABSTRACT FROM AUTHOR]

The transition from terrestrial to marine environments by secondarily aquatic tetrapods necessitates a suite of adaptive changes associated with life in the sea, e.g., the scaleless skin in adult individuals of the extant leatherback turtle. A partial, yet exceptionally preserved hard-shelled (Pan-Cheloniidae) sea turtle with extensive soft-tissue remains, including epidermal scutes and a virtually complete flipper outline, was recently recovered from the Eocene Fur Formation of Denmark. Examination of the fossilized limb tissue revealed an originally soft, wrinkly skin devoid of scales, together with organic residues that contain remnant eumelanin pigment and inferred epidermal transformation products. Notably, this stem cheloniid—unlike its scaly living descendants—combined scaleless limbs with a bony carapace covered in scutes. Our findings show that the adaptive transition to neritic waters by the ancestral pan-chelonioids was more complex than hitherto appreciated, and included at least one evolutionary lineage with a mosaic of integumental features not seen in any living turtle. [ABSTRACT FROM AUTHOR]

In marine turtles it is well established that the shorter light wavelengths in the visible and near-ultraviolet spectrum provide more potent, and preferred, cues for nocturnal seafinding orientation than the longer light wavelengths. In this study, we simultaneously presented leatherback hatchlings (Dermochelys coriacea) with a short near-ultraviolet (380 nm) and a longer visible (500 nm) light stimulus to determine whether that preference was based upon differences in light intensity, light wavelength, or a combination of both variables. We found that under light conditions mimicking those at the nesting beach on the darkest evenings, the behavioral preference for the shorter light wavelengths was based upon intensity cues, although we speculate that under brighter illumination, wavelength cues might also be utilized. [ABSTRACT FROM AUTHOR]

The micropillar array electrode (µAE) has been widely applied in microchip-based electrochemical detection systems due to a large current response. However, it was found that amplifying the current through further adjusting geometrical parameters is generally hindered by the shielding effect. To solve this problem, a bio-inspired micropillar array electrode (bµAE) based on the microfluidic device has been proposed in this study. The inspiration is drawn from the structure of leatherback sea turtles' mouths. By deforming a μAE to rearrange the micropillars on bilateral sides of the microchannel, the contact area between micropillars and analytes increases, and thus the current is substantially improved. A numerical simulation was then used to characterize the electrochemical performance of bµAEs. The effects of geometrical and hydrodynamic parameters on the current of bµAEs were investigated. Moreover, a prototypical microchip integrated with bµAE was fabricated for detailed electrochemical measurement. The chronoamperometry measurements were conducted to verify the theoretical performance of bµAEs, and the results suggest that the experimental data are in good agreement with those of the simulation model. This work presents a novel bµAE with great potential for highly sensitive electrochemical detection and provides a new perspective on the efficient configuration of the µAE. [ABSTRACT FROM AUTHOR]

The leatherback sea turtle (Dermochelys coriacea) is the largest and one of the most migratory turtle species, inhabiting oceans throughout the world. There has been a steady decline in leatherback populations over the past several decades due to human activities. They are considered endangered in Thailand and global, so conservation strategies are needed to study and protect the species, including determining their genetic diversity. A total of 8 microsatellite loci and 658 bp amplicon of mitochondrial DNA (mtDNA) were used to assess genetic data from 149 dead leatherback turtle hatchlings among 14 nests in five locations along the Andaman Sea, Thailand, between 2018–2020. The microsatellite findings show that the observed heterozygosity (Ho) ranged from 0.44 ± 0.09 to 0.65 ± 0.10. Population structures were further divided into two genetically distinct groups by Bayesian inference. For the mtDNA control region, our samples consisted of three haplotypes. Globally, there are 27 haplotypes of leatherback turtles, with a relatively low genetic diversity (h = 0.43). These results reveal the genetic status of leatherback turtles in Thailand and globally, and raise concerns about their relative genetic health, which highlight the need for proactive, long-term management and conservation strategies for this endangered species. [ABSTRACT FROM AUTHOR]

Despite only comprising seven species, extant sea turtles (Cheloniidae and Dermochelyidae) display great ecological diversity, with most species inhabiting a unique dietary niche as adults. This adult diversity is remarkable given that all species share the same dietary niche as juveniles. These ontogenetic shifts in diet, as well as a dramatic increase in body size, make sea turtles an excellent group to examine how morphological diversity arises by allometric processes and life habit specialisation. Using three-dimensional geometric morphometrics, we characterise ontogenetic allometry in the skulls of all seven species and evaluate variation in the context of phylogenetic history and diet. Among the sample, the olive ridley (Lepidochelys olivacea) has a seemingly average sea turtle skull shape and generalised diet, whereas the green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) show different extremes of snout shape associated with their modes of food gathering (grazing vs. grasping, respectively). Our ontogenetic findings corroborate previous suggestions that the skull of the leatherback (Dermochelys coriacea) is paedomorphic, having similar skull proportions to hatchlings of other sea turtle species and retaining a hatchling-like diet of relatively soft bodied organisms. The flatback sea turtle (Natator depressus) shows a similar but less extreme pattern. By contrast, the loggerhead sea turtle (Caretta caretta) shows a peramorphic signal associated with increased jaw muscle volumes that allow predation on hard shelled prey. The Kemp's ridley (Lepidochelys kempii) has a peramorphic skull shape compared to its sister species the olive ridley, and a diet that includes harder prey items such as crabs. We suggest that diet may be a significant factor in driving skull shape differences among species. Although the small number of species limits statistical power, differences among skull shape, size, and diet are consistent with the hypothesis that shifts in allometric trajectory facilitated diversification in skull shape as observed in an increasing number of vertebrate groups. [ABSTRACT FROM AUTHOR]

Hatching success of sea turtle eggs can be reduced by a variety of biotic and abiotic factors. This study of the nesting ecology of leatherback (Dermochelys coriacea) and green (Chelonia mydas) sea turtles, investigated how several environmental factors and beach characteristics on Bioko Island, Equatorial Guinea influence sea turtle reproductive success. Average hatching success was 40.4% for green turtles and 41.73% for leatherback turtles. For leatherback turtles, clutch elevation relative to the high tide line (HTL) was found to be the most influential factor in determining hatching success, highlighting the sensitivity of this species to sea-level rise (SLR). Multiple linear regression analysis demonstrated that nest distance to vegetation, temperature, sand grain size, location on the beach, and sand conductivity also played significant roles in leatherback clutch hatching success. For leatherback clutches, 33% percent of nests were affected by inundation and 17% by predation. An optimum clutch elevation range for leatherback turtles was identified, where a distinct increase in hatching success was observed between − 0.286 and − 0.0528 m above the HTL. For green sea turtles, 64% of experimental nests were affected by predation, confounding conclusions about the roles of environmental characteristics in green turtle hatching success. We propose further investigation into influential characteristics in green turtle nests and confirmation of the observed optimum elevation range on Bioko Island and other nesting grounds. Identified sensitivities of each species to SLR and beach characteristics will be used to encourage the government of Equatorial Guinea to consider the vulnerability of their resident turtle populations when planning for future coastal development. [ABSTRACT FROM AUTHOR]

After completing embryonic development, marine turtle hatchlings emerge from their subsurface nest, generally at night, and crawl to the ocean ('sea finding'). That response depends upon the ability of the turtles to discriminate between the brighter seaward versus a dimmer landward horizon, followed by a positive phototaxis. While the crawls of most marine turtle hatchlings are well oriented and straight, those of leatherback hatchlings are sometimes interrupted by bouts of circling. We conducted experiments comparing the orientation and crawling behaviour of leatherbacks to those of loggerhead hatchlings to determine why those differences occur. The two species did not differ in the light spectra attracting the hatchlings, but leatherback thresholds for detection and for intensity discrimination were significantly higher than those of loggerheads. At the nesting beach, loggerheads under full (bright) or new (darker) moon conditions crawled straight to the ocean; circling rarely occurred. Leatherback crawls under a full moon were indistinguishable from those of loggerheads, but during new moon trials, when horizon brightness differences approached leatherback intensity discrimination thresholds, circling increased significantly. We conclude that circling is probably used by leatherbacks to reinforce orientation decisions when horizon cues become more difficult to discern. Circling could be costly as it lengthens the crawl and increases exposure to terrestrial predators. We hypothesize that those costs persist because other visual adaptations affecting sensitivity enhance the ability of leatherbacks to detect prey, mates or favourable habitats in an open ocean environment. • We compared leatherback and loggerhead hatchlings' phototaxis responses. • Leatherbacks were less sensitive to wavelengths of 340–580 nm than loggerheads. • Under full moon, both species crawled directly from the nest to the sea. • Under new moon, leatherbacks were less accurate; loggerheads remained unchanged. • These responses may reflect sea-finding orientation–foraging efficiency trade-offs. [ABSTRACT FROM AUTHOR]

Monitoring how populations respond to sustained conservation measures is essential to detect changes in their population status and determine the effectiveness of any interventions. In the case of sea turtles, their populations are difficult to assess because of their complicated life histories. Ground-derived clutch counts are most often used as an index of population size for sea turtles; however, data are often incomplete with varying sampling intensity within and among sites and seasons. To address these issues, we: (1) develop a Bayesian statistical modelling framework that can be used to account for sampling uncertainties in a robust probabilistic manner within a given site and season; and (2) apply this to a previously unpublished long-term sea turtle dataset (n = 17 years) collated for the Republic of the Congo, which hosts two sympatrically nesting species of sea turtle (leatherback turtle [Dermochelys coriacea] and olive ridley turtle [Lepidochelys olivacea]). The results of this analysis suggest that leatherback turtle nesting levels dropped initially and then settled into quasi-cyclical levels of interannual variability, with an average of 573 (mean, 95% prediction interval: 554–626) clutches laid annually between 2012 and 2017. In contrast, nesting abundance for olive ridley turtles has increased more recently, with an average of 1,087 (mean, 95% prediction interval: 1,057–1,153) clutches laid annually between 2012 and 2017. These findings highlight the regional and global importance of this rookery with the Republic of the Congo, hosting the second largest documented populations of olive ridley and the third largest for leatherback turtles in Central Africa; and the fourth largest non-arribada olive ridley rookery globally. Furthermore, whilst the results show that Congo’s single marine and coastal national park provides protection for over half of sea turtle clutches laid in the country, there is scope for further protection along the coast. Although large parts of the African coastline remain to be adequately monitored, the modelling approach used here will be invaluable to inform future status assessments for sea turtles given that most datasets are temporally and spatially fragmented.

The northwest Atlantic leatherback sea turtle (Dermochelys coriacea) population is exhibiting decreasing trends along numerous nesting beaches. Since population health and viability are inherently linked, it is important to establish species- and life-stage class-specific blood analyte reference intervals (RIs) so that effects of future disturbances on organismal health can be better understood. For hatchling leatherbacks, the objectives of this study were to (1) establish RIs for morphometrics and blood analytes; (2) evaluate correlations between hatchling morphometrics, blood analytes, and hatching success; and (3) determine temporal trends in hatchling morphometrics and blood analytes across nesting season. Blood samples were collected from 176 naturally emerging leatherback hatchlings from 18 clutches. Reference intervals were established for morphometrics and blood analytes. Negative relationships were noted between hatchling mass and packed cell volume, total white blood cells, heterophils, lymphocytes, and total protein and between body condition index (BCI) and immature red blood cells (RBC), RBC polychromasia and anisocytosis, and total protein. Clutch deposition date showed positive relationships with lymphocytes and total protein, and negative relationships with hatchling mass and BCI. Hatching success was positively correlated with mass, and negatively with total protein and glucose, suggesting that nutritional provisions in eggs, incubation time, and/or metabolic rates could change later in the season and affect survivorship. These various observed correlations provide evidence for increased physiological stress (e.g., inflammation, subclinical dehydration) in hatchlings emerging later in nesting season, presumably due to increased nest temperatures or other environmental factors (e.g., moisture/rainfall). Data reported herein provide morphometric and blood analyte data for leatherback hatchlings and will allow for future investigations into spatiotemporal trends and responses to various stressors. [ABSTRACT FROM AUTHOR]

Background: Sea turtle hatchlings must avoid numerous predators during dispersal from their nesting beaches to foraging grounds. Hatchlings minimise time spent in predator-dense neritic waters by swimming almost continuously for approximately the first 24 h post-emergence, termed the 'frenzy'. Post-frenzy, hatchling activity gradually declines as they swim in less predator-dense pelagic waters. It is well documented that hatchlings exhibit elevated metabolic rates during the frenzy to power their almost continuous swimming, but studies on post-frenzy MRs are sparse. Results: We measured the frenzy and post-frenzy oxygen consumption of hatchlings of five species of sea turtle at different activity levels and ages to compare the ontogeny of mass-specific hatchling metabolic rates. Maximal metabolic rates were always higher than resting metabolic rates, but metabolic rates during routine swimming resembled resting metabolic rates in leatherback turtle hatchlings during the frenzy and post-frenzy, and in loggerhead hatchlings during the post-frenzy. Crawling metabolic rates did not differ among species, but green turtles had the highest metabolic rates during frenzy and post-frenzy swimming. Conclusions: Differences in metabolic rate reflect the varying dispersal stratagems of each species and have important implications for dispersal ability, yolk consumption and survival. Our results provide the foundations for links between the physiology and ecology of dispersal of sea turtles. [ABSTRACT FROM AUTHOR]

on November 5, 2015, the rupture occurred of the Fundão dam of the mining company Samarco, located in the sub-district of Bento Rodrigues/MG, 35 km from the center of the Brazilian municipality of Mariana/MG, approximately 16.000 Olympic pools of mining residue circulated through the district of Bento Rodrigues in a period of only 11 minutes. The plume of this environmental impact extended approximately 800 km in the Rio Doce basin, between Minas Gerais and Espirito Santo. The Ipiranga river, located between Linhares/ES and São Mateus/ES, was one of the last sites affected by the waste from the Doce river basin, having contact with the sea in the Urussuquara/ES restinga, a place that is a nursery of sea turtles. A total of 23 nests were surveyed with homogeneous distribution along the coast, the species with the greatest abundance of records was Chelonia mydas (LINNAEUS, 1758) with 17 nests, followed by the species Caretta caretta (LINNAEUS, 1758) with 5 nests, followed by the species Dermochelys coriacea (LINNAEUS, 1766) with 1 raised nest. Therefore, Urussuquara beach should be considered as a priority locus of mundial importance for the protection and conservation of sea turtles. [ABSTRACT FROM AUTHOR]

The nesting characteristics (number of nests and eggs, time of year, nesting initiation, and nesting length) of leatherback (Dermochelys coriacea) and hawksbill (Eretmochelys imbricata) sea turtles of the southern Caribbean Sea (specifically in the Gulf of Paria in Venezuela), were examined in association with weekly precipitation averages and number of rainy days per week during the period between 2009 and 2018. We hypothesized about the influence of rainfall intensity and patterns as the main abiotic factor for sea turtle nesting. On average, leatherbacks preferred nesting during the drier season of each year (March, April, and May), while hawksbills nested during the rainy season (June to September). For both species, we found few significant correlations between the number of nests or clutch size (number of eggs per nest) and weekly averages of seasonal precipitation rates in the region. Average hawksbill clutch sizes were not correlated with average precipitation rates but were positively correlated with the number of rainy days per week (r=0.66, P≤0.05). Average hawksbill clutch sizes decreased each year on average (-3.3 eggs/year, r=-0.88, P≤0.001), which coincided with a negative long-term trend in the number of rainy days (-0.11 rainy days/week, r=-0.69, P≤0.05). During the study period, nesting activities for both leatherback and hawksbills started progressively later (0.9 and 0.6 weeks/year, respectively p≤0.05) and were shorter (-0.9 and -0.8 weeks /year, P≤0.1 and P≤0.05, respectively). [ABSTRACT FROM AUTHOR]

The recovery of depleted sea turtle populations will require careful documentation of sea turtle reproduction sites and anthropogenic mortality risks throughout their known ranges. Although sea turtle nesting is well documented in many locations, there remains a paucity of data on the species and nesting ecology in western Africa. Here we provide the first longitudinal study of sea turtle nesting activity in Ghana. In decreasing order of abundance, we observed nesting olive ridley (Lepidochelys olivacea) (60 nests/yr), leatherback (Dermochelys coriacea) (17 nests/yr), and green (Chelonia mydas) sea turtles (2 nests/yr) along 3.7 km of beach. The primary nesting season for all species is September through January; however, olive ridley turtles sporadically nest throughout the year. Olive ridley nesting activity significantly declined during the study period (R2 = 0.53, p = 0.04). The primary risk factors for these animals are fishery bycatch, direct harvest of nesting females, and egg poaching. [ABSTRACT FROM AUTHOR]

Five species of sea turtle—the green (Chelonia mydas), hawksbill (Eretmochelys imbricata), leatherback (Dermochelys coriacea), loggerhead (Caretta caretta), and olive ridley (Lepidochelys olivacea)—feed in the coastal waters of India, nest on the mainland and island beaches, and are an important component of India's natural and sociocultural heritage. Sea turtles spend most of their life cycle at sea, so structured studies of the biology of nonnesting populations are challenging. However, fishers' ecological knowledge (FEK) could indicate sea turtle distribution, abundance, and population trends. Structured interviews with 93 male fishers at Sagareshwar Beach, Vengurla, in the Sindhudurg District of Maharashtra revealed observations of all 5 sea turtle species in local waters. Importantly, this was the first known record of loggerhead turtles for the Sindhudurg District of the state coastline and added to infrequent records of leatherback turtles over the previous 20 yrs. Observations were more common at a time when adult turtles are likely to be courting and mating, although this behavior was not observed. Fishers did not contribute ecological knowledge about sea turtle distribution from the waters they fished, potentially because of the method used to collect information on maps or reluctance to indicate areas fished. Estimates of abundance were widely disparate, but perceived decreases in the size of local populations were common among respondents. Outcomes of our study suggest that the FEK of small-scale coastal fishers operating in even a small area is of value in identifying potential areas for focused investigations on in-water populations of sea turtles. [ABSTRACT FROM AUTHOR]

Background: Sea turtles, which are globally endangered species, have been stranded and found as bycatch on the Korean shore recently. More studies on sea turtles in Korea are necessary to aid their conservation. To investigate the spatio-temporal occurrence patterns of sea turtles on the Korean shore, we recorded sampling locations and dates, identified species and sexes and measured sizes (maximum curved carapace length; CCL) of collected sea turtles from the year 2014 to 2020. For an analysis of diets through stomach contents, we identified the morphology of the remaining food and extracted DNA, followed by amplification, cloning, and sequencing. Results: A total of 62 stranded or bycaught sea turtle samples were collected from the Korean shores during the study period. There were 36 loggerhead turtles, which were the dominant species, followed by 19 green turtles, three hawksbill turtles, two olive ridley turtles, and two leatherback turtles. The highest numbers were collected in the year 2017 and during summer among the seasons. In terms of locations, most sea turtles were collected from the East Sea, especially from Pohang. Comparing the sizes of collected sea turtles according to species, the average CCL of loggerhead turtles was 79.8 cm, of green turtles was 73.5 cm, and of the relatively large leatherback turtle species was 126.2 cm. In most species, the proportion of females was higher than that of males and juveniles, and was more than 70% across all the species. Food remains were morphologically identified from 19 stomachs, mainly at class level. Seaweeds were abundant in stomachs of green turtles, and Bivalvia was the most detected food item in loggerhead turtles. Based on DNA analysis, food items from a total of 26 stomachs were identified to the species or genus level. The gulfweed, Sargassum thunbergii, and the kelp species, Saccharina japonica, were frequently detected from the stomachs of green turtles and the jellyfish, Cyanea nozakii, the swimming crab, Portunus trituberculatus, and kelps had high frequencies of occurrences in loggerhead turtles. Conclusions: Our findings support those of previous studies suggesting that sea turtles are steadily appearing in the Korean sea. In addition, we verified that fish and seaweed, which inhabit the Korean sea, are frequently detected in the stomach of sea turtles. Accordingly, there is a possibility that sea turtles use the Korean sea as feeding grounds and habitats. These results can serve as basic data for the conservation of globally endangered sea turtles. [ABSTRACT FROM AUTHOR]

Sea turtles harbour epizoic diatoms of which several taxa are considered exclusively epizoic and possible 'commensals'. The epizoic diatom communities were examined from 124 individuals representing four turtle species (Chelonia mydas, Eretmochelys imbricata, Lepidochelys olivacea and Dermochelys coriacea), from three well-defined areas: Eastern Caribbean, Equatorial West Atlantic and South Pacific. Overall, the epizoic diatoms are very small and need electron microscopy to be accurately identified. Non-Metric MultiDimensional Scaling analyses permitted us to evaluate these diatom assemblages according to turtle species and biogeography. Differentiation was mainly driven by 14 taxa in the diatom genera Chelonicola, Tripterion, Tursiocola, Olifantiella, Navicula and Achnanthes. The highest diatom species richness was found associated with E. imbricata. Dermochelys coriacea and L. olivacea exhibit lower diatom diversities. Some difference in colonization was detected between C. mydas adults and juveniles at the same site, with higher diatom diversity for the juveniles. Within C. mydas we show geographic differentiation of their diatom assemblages, particularly between populations of the Equatorial West Atlantic and South Pacific. Two Tursiocola species 'commensal' to C. mydas seemed to be geographically restricted to French Guiana and the Caribbean. Dermochelys coriacea has a diatom assemblage very different from those of the three other turtles, probably due to its particular behaviour. Lepidochelys olivacea is also unique in the complete lack of Chelonicola species. Based on our results, the diatoms Tripterion societatis and Chelonicola spp. (as currently defined) appear to be mutually exclusive on turtle hosts. This study adds significantly to our understanding of the global distribution of epizoic diatoms on sea turtles. We discuss to what extent these diatoms can be used as a geographic marker with regard to the biogeography of the diatoms themselves and their host. [ABSTRACT FROM AUTHOR]

In this work we studied total arsenic concentrations in liver, muscle and kidney of 49 individuals of two sea turtle species (loggerhead sea turtles, n = 45; leatherback turtles, n = 4) stranded in Murcia (South-eastern Spain) coastline between 2009 and 2018. In accordance with the literature, muscle was the tissue with the highest concentrations in both species, followed by liver and kidney. Although differences in arsenic concentrations were not statistically significant between the study species, loggerhead sea turtles showed concentrations two or three times higher than those of leatherback turtles, which we attribute to differences on feeding behavior and habitat preferences. Arsenic concentrations in turtles from this area increase evidence of western Mediterranean Sea as a hotspot for metal pollution. Based on the scarce existing knowledge on arsenic toxicity in sea turtles, those levels found in our study are below those responsible for liver damage. [ABSTRACT FROM AUTHOR]

Leatherback marine turtles are the largest extant turtles with some individuals measuring up to 2 m in carapace length. In addition, this species remains in oceanic habitat during much its life, making it difficult to investigate its ontogeny from hatchling to adult stage. Furthermore, distinct chondro‐osseous (cartilage and bone) tissue morphology has led to speculation that sexual maturity may be reached as early as 3 years while others have estimated a minimum of 25 years to reach adulthood. Using a combination of reanalysis of the growth trajectories of juveniles maintained in captivity, and the age–size relationship of individuals in the field, we demonstrate and quantify the indeterminate growth of this species. Using comparisons of female size distribution on nesting beaches and stranded or captured‐at‐sea size distributions adjusted with a new asymmetric sigmoid function, we were able to model the size reaction norm for female sexual maturity. Combining these two models, we show that some females may reach maturity at 14 years in natural conditions, while others will take 50 years or more. Sexual maturity may even be reached at 5 years when individuals experience exceptionally good environmental conditions. This extreme plasticity in the age of sexual maturity has been demonstrated in loggerhead turtles in natural conditions and in green turtles in captivity. It may be a general life‐history feature of marine turtles. [ABSTRACT FROM AUTHOR]

Background: Transcriptomic data has demonstrated utility to advance the study of physiological diversity and organisms' responses to environmental stressors. However, a lack of genomic resources and challenges associated with collecting high-quality RNA can limit its application for many wild populations. Minimally invasive blood sampling combined with de novo transcriptomic approaches has great potential to alleviate these barriers. Here, we advance these goals for marine turtles by generating high quality de novo blood transcriptome assemblies to characterize functional diversity and compare global transcriptional profiles between tissues, species, and foraging aggregations. Results: We generated high quality blood transcriptome assemblies for hawksbill (Eretmochelys imbricata), loggerhead (Caretta caretta), green (Chelonia mydas), and leatherback (Dermochelys coriacea) turtles. The functional diversity in assembled blood transcriptomes was comparable to those from more traditionally sampled tissues. A total of 31.3% of orthogroups identified were present in all four species, representing a core set of conserved genes expressed in blood and shared across marine turtle species. We observed strong species-specific expression of these genes, as well as distinct transcriptomic profiles between green turtle foraging aggregations that inhabit areas of greater or lesser anthropogenic disturbance. Conclusions: Obtaining global gene expression data through non-lethal, minimally invasive sampling can greatly expand the applications of RNA-sequencing in protected long-lived species such as marine turtles. The distinct differences in gene expression signatures between species and foraging aggregations provide insight into the functional genomics underlying the diversity in this ancient vertebrate lineage. The transcriptomic resources generated here can be used in further studies examining the evolutionary ecology and anthropogenic impacts on marine turtles. [ABSTRACT FROM AUTHOR]

Sea turtles, like other air-breathing diving vertebrates, commonly experience significant gas embolism (GE) when incidentally caught at depth in fishing gear and brought to the surface. To better understand why sea turtles develop GE, we built a mathematical model to estimate partial pressures of N2 (PN2), O2 (PO2), and CO2 (PCO2) in the major body-compartments of diving loggerheads (Caretta caretta), leatherbacks (Dermochelys coriacea), and green turtles (Chelonia mydas). This model was adapted from a published model for estimating gas dynamics in marine mammals and penguins. To parameterize the sea turtle model, we used values gleaned from previously published literature and 22 necropsies. Next, we applied this model to data collected from free-roaming individuals of the three study species. Finally, we varied body-condition and cardiac output within the model to see how these factors affected the risk of GE. Our model suggests that cardiac output likely plays a significant role in the modulation of GE, especially in the deeper diving leatherback turtles. This baseline model also indicates that even during routine diving behavior, sea turtles are at high risk of GE. This likely means that turtles have additional behavioral, anatomical, and/or physiologic adaptions that serve to reduce the probability of GE but were not incorporated in this model. Identifying these adaptations and incorporating them into future iterations of this model will further reveal the factors driving GE in sea turtles. [ABSTRACT FROM AUTHOR]

Endangered leatherback sea turtles (Dermochelys coriacea) are wide‐ranging, long‐distance migrants whose movements are often associated with environmental cues. We examined the spatial distribution and habitat use for 33 satellite‐tracked leatherbacks from nesting beaches on the Caribbean coast of Costa Rica and Panama from 2004 to 2018, an important nesting population for the leatherback Northwest Atlantic Distinct Population Segment. Tracking revealed the use of two distinct regions, the Gulf of Mexico (GoM, n = 18) and the North Atlantic Ocean (NAO, n = 15). We developed density utilization maps to elucidate high‐use habitats, migration pathways, and seasonal movements. GoM leatherbacks were found in three concentrated high‐use habitats connected by a migration pathway, while NAO leatherbacks were primarily found in a single, large high‐use habitat. Leatherbacks in both regions have the potential to interact with Atlantic pelagic longline fisheries based on seasonal overlap with high fishing effort. Our findings suggest that the GoM is an important destination for leatherbacks from the Caribbean coast of Central America with seasonal movements between high‐use habitats within the GoM. While leatherbacks are utilizing high‐use habitats in both the NAO and the GoM, the proportion of individuals migrating into the GoM increased over the study period. Additionally, NAO leatherbacks have increased the distance they travel in the first 90 d. Regional differences in movement and spatial distribution of high‐use habitats are important considerations when developing conservation plans for the Northwest Atlantic leatherback population. [ABSTRACT FROM AUTHOR]

Although the visual and geomagnetic orientation cues used by sea turtle hatchlings during sea-finding have been well studied, the potential for auditory stimuli to act as an orientation cue has not been explored. We investigated the response of sea turtle hatchlings to natural and anthropogenic noises present on their nesting beaches during sea-finding. The responses of hatchling leatherback sea turtles, Dermochelys coriacea, collected from the Sandy Point National Wildlife Refuge, St. Croix, were measured in the presence of aerial acoustic sounds within hatchlings' hearing range of 50 to 1600 Hz. The highest sound energy produced by beach waves occurs at frequencies 50–1000 Hz, which overlaps with the most sensitive hearing range of hatchling leatherbacks (50–400 Hz). Natural beach wave sounds, which have highest sound energy at frequencies of 50–1000 Hz, may be masked by human conversations (85–650 Hz) and vehicle traffic noise (60–8000 Hz). In the presence of three stimuli, a) beach wave sounds (72.0 dB re: 20 μPa), b) human conversation (72.4 dB re: 20 μPa), and c) vehicle traffic noise (71.1 dB re: 20 μPa), hatchlings exhibited no phonotaxic response (wave sounds: mean angle = 152.1°, p = 0.645; human conversation: mean angle = 67.4°, p = 0.554; traffic noise: mean angle = 125.7°, p = 0.887). These results may be due to the hatchlings being unable to localize sounds in the experimental arena. Visual and auditory cues may also converge to affect sea-finding orientation. Future studies should focus on the localization ability of sea turtles and on the role that sound may play in orientation when combined with other sensory and environmental cues. [ABSTRACT FROM AUTHOR]

The growing demand for fish around the world is an immediate threat to marine megafauna that are unintentionally captured in commercial and artisanal fishery operations. Bycatch mitigation strategies, such as turtle excluder devices, circle hooks, and net illumination, have successfully reduced this risk in some fisheries. We explored the effectiveness of gillnet illumination to reduce sea turtle captures in 2 artisanal fisheries (Mankoadze and Winneba, Ghana) under normal fishing conditions. We first quantified sea turtle bycatch in Ghana's artisanal gillnet fishery from 15 boats for 12 months. We then quantified catch of targeted species and sea turtle bycatch from 20 boats for 15 months (7427 net sets). For 10 of these boats, we placed a Centro Economy green light (1 LED) at each 10‐m interval on the net. We also quantified target catch and sea turtle bycatch from 30 boats for 8 months (2250 net sets). In 15 of these boats, a Centro Deluxe green light (3 LEDs) was installed at 15‐m intervals. Boats with economy lights and those with deluxe lights both exhibited an 81% decrease in sea turtle captures (W = 1, p < 0.001, n = 20; W = 215, p < 0.001, n = 30, respectively) compared with control boats without lights. Illuminated nets resulted in fewer turtle catches for leatherback (Dermochelys coriacea), olive ridley (Lepidochelys olivacea), and green sea turtles (Chelonia mydas) (p < 0.05 for all species). Target catch (mass) (W = 53, p = 0.853 n = 20; W = 76, p = 0.449, n = 23) and value (W = 50, p = 1, n = 20; W = 69, p = 0.728, = 23) were not different across treatments. Our study affirms net illumination can reduce capture rates of 3 species of sea turtles, including the imperiled leatherback. Gear modification methods can successfully reduce bycatch if they are affordable and have broad applications for multiple species in different fisheries. Article impact statement: Net illumination reduces capture rates of 3 species of sea turtles, including the imperiled leatherback. [ABSTRACT FROM AUTHOR]

· Most marine turtles have a typical annual nesting season, and the number of nests laid during a season can be used as a proxy for population size to define trends and conservation status. · However, in some cases, two peaks in female emergences are detected during single year. · We show that estimates that fail to consider this bimodality into account can provide biased results both in terms of describing the phenology and quantifying the number of nests. · The shifts in nesting could be a strategy to adapt to present-day incubation temperatures, hatching success rates, and sex ratios in the context of climate warming. The seasonality of egg-laying in marine turtles is a well-known phenomenon that has been used to determine population trends based on an integration of the number of female emergences or nests during a season. However, in some cases, several peaks in female emergences are detected during single year. In this paper, we explore three such situations, two involving leatherback turtles laying eggs in French Guiana and in Northwest Coast of Papua, Indonesia and another involving green turtles in the Indian Ocean. In the three cases, we demonstrate the existence of a bimodal nesting season using a new statistical model. With this model, we show that estimates that fail to consider this bimodality into account can provide biased results both in terms of describing the phenology and quantifying the number of nests. The origin of these different groups of females is discussed based on the available information. This new model opens the door to a more rigorous analysis of egg-laying seasonality in marine turtles. Such rigor is essential in the current context of climate change, where shifts in seasonality can have a major influence on these species due to their temperature-sensitive sex determination. [ABSTRACT FROM AUTHOR]