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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]

Interaction with fishing gears represents the main anthropogenic threat at sea for sea turtles worldwide, and identifying the hotspots of turtle bycatch is a priority knowledge gap.Turtle stranding data represent a source of information about mortality areas at sea that are not fully exploited. This study aims to infer turtle mortality areas of turtles stranded along the Italian Adriatic Coast in the period 2019–2021 (1432 records), through backtrack modelling of carcasses. Specifically, the decomposition process of eight loggerhead carcasses was monitored, and the relationship between floating period (FP), turtle size and sea temperature was modelled through a generalized additive model. Oceanographic information was then used to track the routes of floating carcasses back, knowing their size and decomposition stage, and finally estimate the likely area of mortality. A complementary numerical experiment of connectivity between coastal and offshore areas gave indication that areas of potential mortality are relatively close to the coast, particularly in the northern Adriatic.Stranded turtles probably represent just a small fraction (17%–25%) of total at‐sea mortalities in the study area (Italian Adriatic waters), with decomposition rates, season and distance from shore influencing their stranding likelihood. Hence, strandings can inform only about spatio‐temporal variability of coastal mortality hotspots.Inferred areas of turtle mortality were most likely located in the North and Central Adriatic all over the year and overlap with heatmaps of fishing effort, obtained from vessel monitoring system (VMS) and automatic identification system (AIS) data, in the Gulf of Manfredonia and in the North‐West Adriatic in the cold (September–December) and warm (May–August) periods, respectively. [ABSTRACT FROM AUTHOR]

Fibropapillomatosis (FP) is a debilitating tumoral disease affecting sea turtles worldwide. While mainly afflicting immature individuals and potentially altering vital functions, the precise impact of this panzootic on turtle health and survival remains unclear. Moreover, the etiological factors implicated in the FP emergence, development and transmission are not yet definitively identified. Among them, an infection by a spreading herpesvirus and the contamination by pollutants (either organic pollutants and trace elements) are suspected. Here, we provide an overview of discoveries, knowledge and propose hypotheses related to FP within five key FP research areas, i.e., virology studies, transmission studies, contamination studies, host genomic studies, and veterinary treatment assays. Moreover, we recommend urgent research avenues to develop at the interface of virology, epidemiology, ecotoxicology, oncology, physiology, immunology, cellular and evolutionary biology, in order to characterize the dynamics of FP and to predict its consequences on sea turtle populations. Importantly, extending the implementation and development of strong collaborations between rehabilitation centers, field biologists and research laboratories at large geographical scale is required to rapidly increase our knowledge on FP and work towards its effective management. [ABSTRACT FROM AUTHOR]

The early evolution of Pan-Chelonioidea (sea turtles) is poorly understood. This is in part due to the rarity of undeformed skulls of definitive early stem chelonioids. In this work, we redescribe the holotype of Nichollsemys baieri using µCT scans and segmentations of the skull. This fossil is the best 3D preserved skull of any Campanian sea turtle, and includes partial "soft tissue" preservation. Nichollsemys is morphologically similar but clearly distinct from Toxochelys spp., and both show a mosaic of plesiomorphic and derived chelonioid features. The internal cranial anatomy documents the presence of derived characters in Nichollsemys baieri that are absent in Toxochelys spp., such as the loss of the epipterygoids and the rod-like shape of the rostrum basisphenoidale. Among the numerous plesiomorphic characters is the presence of a splenial bone, which was unnoticed before. An updated phylogenetic analysis retrieves Nichollsemys baieri as a non-protostegid early stem chelonioid in a slightly more crownward position than Toxochelys latiremis. Our phylogeny includes macrobaenids and protostegids as pan-chelonioids, and we find unorthodox results for dermochelyids. Thus, although Nichollsemys baieri provides important new insights into the early morphological evolution of sea turtles, much work remains to be done. As a completely 3D preserved specimen, we included Nichollsemys baieri into a recent landmark-based skull shape dataset of turtles. Morphospace analysis reveals an intermediate position between cryptodires and crown chelonioids. Based on these data, we also predict that Nichollsemys baieri was still capable of neck retraction, constraining the loss of this trait to more crownward pan-chelonioids. [ABSTRACT FROM AUTHOR]

Simple Summary: In this study, we used both morphology and molecular genetic tools, namely mitochondrial DNA (mtDNA) control region and nuclear DNA (nDNA) exon involving recombination activating gene 2 (RAG2), to confirm the species of two sea turtles found in the Thai Andaman Sea that possessed unusual lateral scute patterns from the original species. Both turtles were identified as the olive ridley turtle (Lepidochelys olivacea). This finding has raised awareness about the need for exploration of rare phenotypes of carapace scute patterns in the olive ridley turtle populations that reside in Thai Seas and the Indo-Pacific region. Two stranded Lepidochelys-like sea turtles were rescued from the Thai Andaman Sea coastline by veterinarians of the Phuket Marine Biological Center (PMBC), one in May of 2019 and another in July of 2021. They were first identified as olive ridley turtles (Lepidochelys olivacea), as the external appearance of both turtles was closer to that species than the other four species found in the Thai Andaman Sea. In fact, when carefully examined, an unusual pattern of the lateral scutes on each turtle was observed, specifically symmetric 5/5 and asymmetric 5/6, both of which are considered rare for L. olivacea and had never been reported in the Thai Andaman Sea. In contrast, this characteristic was more common for the closely related species, Kemp's ridley (L. kempii), although this species is not distributed in the Indo-Pacific Ocean. Thus, we further investigated their genetic information to confirm species identification using two molecular markers, namely the mtDNA control region and nDNA RAG2. The results from the mtDNA control region sequences using the Basic Local Alignment Search Tool (BLAST) indicated that both individuals exhibited a higher percent identity with L. olivacea (99.81–100.00%) rather than L. kempii (94.29–95.41%) or any other species. A phylogenetic tree confirmed that these two turtles belonged to the L. olivacea clade. Moreover, the results of RAG2 also supported the mtDNA result, as both individuals shared the same RAG2 haplotype with L. olivacea. Thus, we have concluded that the two turtles with unusual lateral scute patterns exhibited genetic consistency with their original species, L. olivacea, which has brought attention to the importance of exploring rare phenotypes in sea turtle populations residing in Thai Seas. [ABSTRACT FROM AUTHOR]

Understanding spatial heterogeneity in reproductive success among at-risk populations facing localised threats is key for conservation. Sea turtle populations often concentrate at one nesting site, diverting conservation efforts from adjacent smaller rookeries. Poilão Island, Bijagós Archipelago, Guinea-Bissau, is a notable rookery for green turtles Chelonia mydas within the João Vieira-Poilão Marine National Park, surrounded by three islands (Cavalos, Meio and João Vieira), with lower nesting activity. Poilão's nesting suitability may decrease due to turtle population growth and sea level rise, exacerbating already high nest density. As the potential usage of secondary sites may arise, we assessed green turtle clutch survival and related threats in Poilão and its neighbouring islands. High nest density on Poilão leads to high clutch destruction by later turtles, resulting in surplus eggs on the beach surface and consequently low clutch predation (4.0%, n = 69, 2000). Here, the overall mean hatching success estimated was 67.9 ± 36.7% (n = 631, 2015–2022), contrasting with a significantly lower value on Meio in 2019 (11.9 ± 23.6%, n = 21), where clutch predation was high (83.7%, n = 98). Moderate to high clutch predation was also observed on Cavalos (36.0%, n = 64) and João Vieira (76.0%, n = 175). Cavalos and Meio likely face higher clutch flooding compared to Poilão. These findings, alongside observations of turtle exchanges between islands, may suggest a source-sink dynamic, where low reproductive output sink habitats (neighbouring islands) are utilized by migrants from Poilão (source), which currently offers the best conditions for clutch survival. [ABSTRACT FROM AUTHOR]

As part of a sea turtle health monitoring program on the central east coast of Queensland, Australia, stranded and sick green sea turtles (Chelonia mydas) were subjected to necropsy and histopathology. A subset of these turtles had myocarditis of varying severity, which could not be attributed to parasitism by spirorchid flukes or bacterial infections. We, therefore, undertook an investigation to determine whether virus infections might be part of the pathogenesis. Deep sequencing revealed abundant DNA virus contigs in the heart tissue, of which CRESS and circoviruses appeared to be the most consistently present. Further analysis revealed the homology of some of the circoviruses to the beak and feather disease virus. While a causative link to myocarditis could not be established, the presence of these viruses may play a contributing role by affecting the immune system and overall health of animals exposed to pollutants, higher water temperatures, and decreasing nutrition. [ABSTRACT FROM AUTHOR]

Abstract The early evolution of Pan-Chelonioidea (sea turtles) is poorly understood. This is in part due to the rarity of undeformed skulls of definitive early stem chelonioids. In this work, we redescribe the holotype of Nichollsemys baieri using µCT scans and segmentations of the skull. This fossil is the best 3D preserved skull of any Campanian sea turtle, and includes partial “soft tissue” preservation. Nichollsemys is morphologically similar but clearly distinct from Toxochelys spp., and both show a mosaic of plesiomorphic and derived chelonioid features. The internal cranial anatomy documents the presence of derived characters in Nichollsemys baieri that are absent in Toxochelys spp., such as the loss of the epipterygoids and the rod-like shape of the rostrum basisphenoidale. Among the numerous plesiomorphic characters is the presence of a splenial bone, which was unnoticed before. An updated phylogenetic analysis retrieves Nichollsemys baieri as a non-protostegid early stem chelonioid in a slightly more crownward position than Toxochelys latiremis. Our phylogeny includes macrobaenids and protostegids as pan-chelonioids, and we find unorthodox results for dermochelyids. Thus, although Nichollsemys baieri provides important new insights into the early morphological evolution of sea turtles, much work remains to be done. As a completely 3D preserved specimen, we included Nichollsemys baieri into a recent landmark-based skull shape dataset of turtles. Morphospace analysis reveals an intermediate position between cryptodires and crown chelonioids. Based on these data, we also predict that Nichollsemys baieri was still capable of neck retraction, constraining the loss of this trait to more crownward pan-chelonioids.

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.

As a sea turtle conservation area, Alas Purwo National Park (APNP) shows different patterns in the four species of turtles that have nesting records, such as an increase in Olive Ridley Turtle (Lepidochelys olivacea), stability in Green Turtle (Chelonia mydas), and a decline in Hawksbill Turtle (Eretmochelys imbricata) and Leatherback Turtle (Dermochelys coriacea). During the survey, which lasted from January to July 2023, we discovered that each type of sea turtle preferred nesting sites at specific hypothetical stations, except for the L. olivacea, which nested at all hypothetical stations along Pancur-Cungur Coast. We also discovered that it is highly encouraged to continue relocations that have already been carried out, given the variety of predators encountered during the survey period. This discovery supports the need for in situ conservation at preferred sites for sea turtle species. [ABSTRACT FROM AUTHOR]

We evaluate the frequency of flipper amputation and its impact on reproduction in the threatened loggerhead turtle (Caretta caretta) population of the Eastern Atlantic, through a long‐term study on several high‐density nesting beaches of Cabo Verde. 5982 adult females were individually identified, tagged and measured, and the presence of limb amputations was recorded. 918 of them had one or multiple amputations of the rear or front flippers. Most of these turtles (n = 778) had partial rather than complete flipper amputations. However, we found no difference in body condition indices (1.2 vs. 1.1), clutch size (82 vs. 83 eggs), or hatching success (79 vs. 80%) between amputated and non‐amputated females. While amputations may cause individual mortality or reduced fitness, our results indicate that some amputated turtles successfully nest and survive across multiple nesting seasons. Moreover, the amputations do not appear to be impacting the strong recovery of this population. This study provides evidence of the successful reproductive capacity of amputated loggerhead sea turtles and, by extension, the potential reproductive success of amputees released from recovery centers. [ABSTRACT FROM AUTHOR]

Monitoring of sea turtle nesting beaches in Türkiye have been conducted since 1988 and the number of beaches reached to 22. Mediterranean coast of Türkiye has many small pocket beaches and other inaccessible remote sandy beaches. In this study, I introduce a new nesting site, Yakacık Beach, for the loggerhead turtles (Caretta caretta) in the border of Antalya and Mersin provinces. Following the preliminary field studies on the 1.7 km long beach, 201 and 197 nests were found in 2020 and 2021, respectively, and the average nest density of the two years was calculated as 117.6 nests/km-1. Satellite images were also used to ensure and estimate the number of nests. The number of nest and the nest density were compared with the literature and Yakacık has the second highest nest density in Türkiye with a high predation rate up to 68%. The potential importance of Yakacık Beach and threats to the nesting beach and mitigation measures were discussed. Türkiye has one of the most important nesting sites for the loggerhead turtles and the green sea turtles (Chelonia mydas) in the Mediterranean, with 17 nesting beaches identified in 1989. With the discovery of additional nesting sites such as Çıralı, Alata, Sugözü, Davultepe, and METUKocahasanlı beaches in the following years, the importance of Türkiye for sea turtle populations in the Mediterranean has gradually increased. With this study, a new nesting beach was identified and the importance of Türkiye for the Mediterranean Sea turtles was emphasized. [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]

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]

This article explores the potential impact of climate change on loggerhead sea turtles in the Alboran Sea. The study focuses on sporadic nesting events in the western Mediterranean, which may indicate a colonization process. Genetic studies have shown past instances of colonization, and current climatic conditions in the western Mediterranean are suitable for nesting. The article also discusses the role of the North Atlantic Oscillation (NAO) in influencing sea turtle migration patterns. The findings have implications for loggerhead turtle conservation and highlight the expansion of nesting range within the Mediterranean basin. In Peru, a citizen science project has observed nesting behavior in two sea turtle species, despite nesting beaches not traditionally being found in the country. However, it is suggested that this may be due to inadequate beach surveys rather than a shift in sea turtle behavior. The absence of similar occurrences outside the Mediterranean suggests that additional factors beyond climate change may be involved. The NAO, which is sensitive to climate change, is expected to contribute to an increase in sporadic nesting on the beaches of the Alboran Sea in the future. [Extracted from the article]

Listeria monocytogenes is a ubiquitous pathogen found both in the environment and food. It can cause listeriosis in a wide range of animals as well as in humans. Investigations on presence, spread and virulence are still limited to terrestrial and human environments. Embracing the One Health Approach, investigating the presence and spread of L. monocytogenes in marine ecosystems and among wildlife, would provide us with useful information for human health. This study investigated the presence of L. monocytogenes and Listeria spp. in two species of sea turtles common in the Mediterranean Sea (Caretta caretta and Chelonia mydas). A total of one hundred and sixty-four carcasses of sea turtles (C. caretta n = 161 and C. mydas n = 3) stranded along the Abruzzo, Molise, Campania, and Calabria coasts, were collected. Brain and fecal samples were taken, enriched, and cultured for the detection of Listeria spp. From the specimens collected, strains of L. monocytogenes (brain n = 1, brain and feces n = 1, multiorgan n = 1 and feces n = 1), L. innocua (feces n = 1 and brain n = 1), and L. ivanovii (brain n = 1) were isolated. Typical colonies were isolated for Whole Genome Sequencing (WGS). Virulence genes, disinfectants/metal resistance, and antimicrobial resistance were also investigated. L. monocytogenes, L. innocua, and L. ivanovii were detected in C. caretta, whilst only L. monocytogenes and L. innocua in C. mydas. Notable among the results is the lack of significant differences in gene distribution between human and sea turtle strains. Furthermore, potentially pathogenic strains of L. monocytogenes were found in sea turtles. [ABSTRACT FROM AUTHOR]

The southern California coast is well known for its surfing, beachfront towns, and high marine biodiversity. Humans share these coastal regions with species such as the green sea turtle (Chelonia mydas; hereafter referred to as “green turtle”). Over the last two decades, East Pacific (EP) green turtles have undergone substantial population recovery. As a result of improved protection efforts at nesting beaches and foraging areas in Michoacán, Mexico beginning in 1979 green turtles have been spotted in more areas and in greater numbers than before since 2014.1 An analysis of existing stranding and sighting data is necessary to protect the growing EP green turtle population and ensure their continued population recovery in highly populated areas along the California coast. While the existing green turtle recovery plan (completed in 1998) addresses EP green turtles, it is dated and does not specifically address current known threats to this population, particularly in southern California. 2 Therefore, this report and accompanying StoryMap (link: https://arcg.is/0eX1zK) provide analyses on time-relevant and local scales. With the support of experts from the National Oceanic and Atmospheric Administration’s (NOAA), National Marine Fisheries Service (NMFS), and the University of California San Diego, I review existing literature, analyze stranding and sighting data, and propose recommendations that could help reduce the human impacts on green turtles in the southern California region if implemented.Storymap for this project can be viewed here: https://storymaps.arcgis.com/stories/391c53f931dd45619347177810259dd3

Fibropapillomatosis (FP) is a debilitating tumoral disease affecting sea turtles worldwide. While mainly afflicting immature individuals and potentially altering vital functions, the precise impact of this panzootic on turtle health and survival remains unclear. Moreover, the etiological factors implicated in the FP emergence, development and transmission are not yet definitively identified. Among them, an infection by a spreading herpesvirus and the contamination by pollutants (either organic pollutants and trace elements) are suspected. Here, we provide an overview of discoveries, knowledge and propose hypotheses related to FP within five key FP research areas, i.e., virology studies, transmission studies, contamination studies, host genomic studies, and veterinary treatment assays. Moreover, we recommend urgent research avenues to develop at the interface of virology, epidemiology, ecotoxicology, oncology, physiology, immunology, cellular and evolutionary biology, in order to characterize the dynamics of FP and to predict its consequences on sea turtle populations. Importantly, extending the implementation and development of strong collaborations between rehabilitation centers, field biologists and research laboratories at large geographical scale is required to rapidly increase our knowledge on FP and work towards its effective management.

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]

Persistent organic pollutants (POPs) are chemical substances widely distributed in the environment by the runoff from anthropic activities and can be distributed and bioaccumulated or biomagnified in the environment, affecting the health of organisms. The sea turtle, Lepidochelys olivacea, is a long-lived organism, with migratory habits and feeding behaviors that allow exposure to various pollutants. This work aimed to determine long-term exposure to POPs in adult olive ridley turtles (L. olivacea), sampled during the nesting season, in "La Escobilla" Sanctuary. Blood samples were collected and processed to obtain plasma. The quantification of POPs in blood was carried out with an extraction technique with a focused ultrasound probe. Twenty-seven POP analytes were determined. The concentrations of hexachlorocyclohexane, endosulfan isomers, dichlorodiphenyltrichloroethane, total polychlorinated biphenyls, and the total sum of POPs found in plasma are higher than those reported in other studies, which reported effects such as hematological and biochemical changes in blood, changes in immune system cells and enzymatic activity related to oxidative stress. These results are important to demonstrate the chronic exposure to POPs in olive ridley turtles in marine ecosystems and to highlight the importance of assessing the associated health risks, considering that these contaminants could be transferred to the offspring and affect future generations of this reptile. It is important to carry out studies that develop conservation strategies for the olive ridley turtle. Also, it is necessary to control the emissions of pollutants into the atmosphere, as well as reduce urban, agricultural, and industrial waste in the environment and marine ecosystems. [ABSTRACT FROM AUTHOR]

Context: Assessing the distribution and abundance of marine fauna and the ecological status of coastal and pelagic ecosystems is key to biodiversity conservation, but the monitoring of mobile marine species raises multiple logistical and financial challenges. Aims: The project describes the distribution, abundance and taxonomic assemblage of several marine megafauna taxa in three subregions of the western and central South Pacific Ocean (New Caledonia, Wallis and Futuna, and French Polynesia). Methods: Large-scale aerial surveys were conducted using a standardised multi-taxon protocol, to characterise the occurrence and abundance of marine megafauna over 2.5 million km2. Analysing more than 122 000 km of transects, the densities of 22 different taxa were estimated: seven taxonomic groups of marine mammals (Physeteridae, Kogiidae, Ziphiidae, Globicephalinae, Small Delphininae, Large Delphininae, and Dugongidae), a single group for hard-shelled sea turtles, three groups of elasmobranchs (including whale sharks), and 11 groups of seabirds (including Phaethontidae, Hydrobatidae, Fregatidae and Sulidae). Key results: Contrasting patterns of species distribution were found. Marine mammal diversity increases north and west, with a distinct species assemblage in New Caledonia, compared to other subregions. A strong latitudinal gradient was observed across French Polynesia, independent of taxa. Conclusions: This study provides the first comparison of marine species assemblages across the three oceanic subregions and sets a regional baseline for the biogeography of marine megafauna in the region. Implications: The taxonomic and spatial extension of the results opens up new perspectives for the development of local conservation measures, especially for taxa with already documented population declines. This study simultaneously describes the spatial distribution and densities of 22 distinct taxonomic groups of marine mammals, sea turtles, elasmobranchs and seabirds over three large oceanic subregions of the western and central South Pacific Ocean. It demonstrates the value of multi-taxa monitoring applied to aerial surveys of offshore marine megafauna, and provides a baseline for future conservation measures. This article belongs to the Collection Marine Mammals in the Pacific. [ABSTRACT FROM AUTHOR]

Context: The pelagic longline fishery has implemented bycatch mitigation measures to reduce sea turtle bycatch, but little attention has been given to their side effects on other endangered species. Aims: To investigate the impact of using circle hooks and whole fish bait on the fishing mortality of target and non-target fish species, as well as bycatch species. Methods Long-term data collected from research cruises conducted by a pelagic longline vessel were used for analysis. A Bayesian quantitative evaluation was employed to assess the effects of the mitigation measures on the fishing mortality of various species. Key results The use of circle hooks led to an increase in mouth-hooking for both target and bycatch species, and the effect was proportional to hook size. Although deploying circle hooks did not increase fishing mortality per unit effort (MPUE) for shortfin mako sharks, combining to whole fish bait had a significant increase on MPUE. Conclusions: The study stresses the need for considering the trade-offs of bycatch mitigation measures such as circle hooks and fish bait among multi-taxa species. Implications: The necessity for quantitative assessments of bycatch mitigation measures before implementation is highlighted to avoid unintended consequences on endangered species and ensure effective conservation in pelagic longline fisheries. Pelagic longline fisheries developed bycatch mitigation measures, replacing J/tuna hooks and squid bait with circle hooks and whole-fish bait to reduce sea turtle bycatch. However, they overlooked the effects on other endangered species. Long-term data showed that circle hooks increased mouth-hooking in both target and bycatch species, proportional to their size. Although circle hooks with squid bait did not increase fishing mortality per unit effort (MPUE) for shortfin mako sharks, combining to whole-fish bait significantly increased MPUE. It highlights the need for quantitative assessments before implementing bycatch mitigation measures. [ABSTRACT FROM AUTHOR]

Multi-species assemblages can help identify key resources in their habitat by evaluating how they are partitioning their resources. Here we used the isotopic niche of loggerhead, Kemp's ridley, and green sea turtles to assess their ecological niche within a Gulf of Mexico bay. Additionally, we assessed temporal and size-class variation in their diets by comparing the δ13C and δ15N values over various capture years and size classes. Based on the isotopic niche overlap results, interspecific competition occurs among loggerhead, Kemp's ridley, and smaller green turtles. Green turtle and Kemp's ridley diet varied by size class, while Kemp's ridley diet also varied temporally. The three species partition resources by selecting different preferred diet items, although some overlap in diet, including between the herbivorous (green) and carnivorous (Kemp's ridley, loggerhead) species, appears to occur. The high quality of this habitat may allow species co-existence and population recovery despite the possible use of shared resources. [ABSTRACT FROM AUTHOR]

Simple Summary: This study examined the use of a permanent esophago-gastric tube (EG tube) in sea turtles as an alternative to force-feeding. The study included 195 marine turtles that had surgery to place a permanent EG tube between 2008 and 2022. Loggerhead turtles (Caretta caretta) needed EG tube placement due to their poor health for various diseases, which were categorized. The study analyzed the duration of EG tube placement in relation to the animals' condition and injuries, considering any complications or differences between the two facilities. Efficient nutritional support plays a pivotal role in the rehabilitation of sea turtles, ensuring a positive, swift, and successful recovery from clinical conditions for their reintroduction into the wild. For sea turtles in severely emaciated and underweight condition, the primary objective is to facilitate weight gain in terms of both muscle mass and fat reserves. Traditionally, many sea turtle rehabilitators have employed the practice of force-feeding, which also involves the daily insertion of an orogastric tube from the mouth to the stomach. However, this technique may be highly stressful for the animals, carrying the risks of regurgitation and potential harm, requiring the removal of the animal from the water, and subjecting it to uncomfortable and potentially dangerous handling. The procedure may also involve risks for operators. In this study, we explore the utilization of a permanent esophago-gastric tube (EG tube) in sea turtles as an alternative to force-feeding, providing a respectful and appropriate approach to meeting the nutritional needs of patients. The administration of food, essential medications, and fluids is performed directly with the turtle in its tank, minimizing the stress associated with handling, while ensuring the safety of operators. The study involves 195 marine turtles that underwent surgery for the placement of a permanent EG tube between 2008 and 2022. Of these, 116 animals were treated at the Sea Turtle Clinic of the Department of Veterinary Medicine at the University of Bari, South Adriatic Sea, Puglia (IT), and 79 patients were admitted to the Sea Turtle Rescue Center of Lampedusa, Central Mediterranean Sea, Sicily (IT). The loggerhead turtles (Caretta caretta) required EG tube placement due to their poor condition related to various diseases, which were systematically categorized. The duration of EG tube placement was analyzed regarding the specific condition of the animals and the nature of their injuries, considering any complications or differences between the two facilities. The results of the study will provide valuable information for the ongoing care and treatment of marine turtles in rehabilitation facilities. [ABSTRACT FROM AUTHOR]

Coastal seagrass habitats are critical foraging grounds for endangered green turtles (Chelonia mydas). However, these habitats are vulnerable to anthropogenic effects, potentially leading to their degradation with consequent impacts on the health status of foraging green turtles.Two foraging habitats of green turtles in Tun Mustapha Park, Sabah, Malaysia were surveyed: Kudat Mainland and Balambangan Island, by capturing green turtles and evaluating their physical body condition as well as assessing seagrass cover.Despite having similar genetic compositions, the Kudat Mainland aggregation had significantly higher body size (curved carapace length: 61.7 ± 14.5 cm, body weight: 30.0 ± 22.2 kg), Fulton's body condition index (BCI: 1.49 ± 0.13), barnacle (Chelonibia testudinaria) occurrence (78.8%) and barnacle abundance (5.46 ± 9.90 barnacles/turtle) than the Balambangan Island aggregation (curved carapace length: 51.6 ± 8.1 cm, body weight: 17.3 ± 7.7 kg, BCI: 1.40 ± 0.09, barnacle occurrence: 31.0%, barnacle abundance: 0.50 ± 0.92 barnacles/turtle). The differences in BCI between the nearby aggregations could not be attributed to size and barnacle occurrence differences, suggesting the foraging habitat is the primary factor affecting the body condition of green turtles.Seagrass cover at Kudat Mainland was only slightly higher than at Balambangan Island. These findings suggest that the body condition of green turtles is potentially sensitive to the quality of foraging habitats such as nutrients and water quality.It is crucial to monitor the health of foraging habitats and their impact on the body condition of turtles. It is recommended that habitat‐turtle dynamics are given conservation priority, in parallel to water quality monitoring – with action taken to reduce pollution if necessary. A holistic approach to turtle conservation is therefore required. [ABSTRACT FROM AUTHOR]

Forty‐seven free‐ranging sea turtles (46‐ Chelonia mydas, 1‐ Eretmochelys imbricata) were examined via novel use of an endoscopy combined with a rectal enema to obtain large fecal sample volumes. The cloaca was insufflated using an endoscope, after which the bladder and rectum separated, allowing access to the colon. Environmental conditions and location influenced the performance of the procedure initially, but after several attempts the procedure was successfully initiated. In all cases, fecal samples were obtained, and the animals were released to their respective locations. Fecal sample collection using this approach enhances the ability to obtain diagnostic information and perform other scientific analyses of sea turtles. [ABSTRACT FROM AUTHOR]

Leatherback sea turtle (Dermochelys coriacea) hatchlings have previously been kept alive for over a year in captive conditions but these were the few survivors of initially larger groups. In this report, newly hatched leatherback sea turtles were randomly harvested from two nests in Thailand and successfully reared before release back to the wild. In captivity, the survival of the turtles decreased sharply during the first 4 or 5 months, and then steadied until the end of the 12‐month trial. The survival of yearlings from one nest was 13.3% and from the other nest 46.7%. Their growth was exponential, reaching 1.36−3.35 kg (n = 9) at the end of program. The causes of death of the reared turtles were accidents (25.0−38.5%) and infections from water and live food (61.5−75.0%). The dietary requirements of the turtles were investigated by determining the digestibility of protein and carbohydrate in vitro, using enzymes from the digestive tracts of hatchlings that had died in an accident (70.1−92.9 g body weight). The results indicated that the most suitable source of protein was wheat gluten, followed by soybean meal, nonruminant meat and bone meal, fish meal, nonruminant meat meal, pork meal, and skimmed milk, while suitable carbohydrate sources were mashed cassava, corn, wheat flour, and alpha starch, followed by cereal meal and rice flour. Findings from the current report provide a practical protocol for head‐starting leatherback sea turtles, and indicate the possible basis of an effective artificial diet for this species. Research Highlights: Survival of yearlings was 46.7% for turtles hatched at the top of the egg chamber.Survival of yearlings was 13.3% for turtles hatched at the bottom of the egg chamber.Accidents and diseases were the main causes of death.In vitro digestibility assays indicated the best food sources for an artificial diet. [ABSTRACT FROM AUTHOR]

The modernization and intensification of fishing practices have raised the threat to sea turtles, with escalating unintentional captures endangering turtles of all life stages. In this study, we examined the impact of artisanal fishing on sea turtles in two coastal regions of Angola, southern Africa. Between August 2015 - March 2016, through participatory monitoring (n = 8) and interviews with fishers (n= 41), we documented unintentional turtle captures occurring year-round during fishing activities. A total of 405 turtles, 403 olive ridley (Lepidochelys olivacea) and 2 green (Chelonia mydas), were caught in gillnets by fishers engaged in participatory monitoring. Net characteristics, including length and proximity to the shoreline, as reported by the interviewed fishers, correlated with those used by the monitoring group. We estimated approximately 1219 turtles captured by the 41 interviewed fishers over the 8-month study period. Most captures occurred within 100 m from the shoreline. The likelihood of accidental turtle captures increased significantly with proximity to the beach, larger mesh sizes, and greater net lengths and number of hauls. We calculated a survival rate of 41%, and a mortality rate of 59% for captured turtles. Number of turtles caught as bycatch varied throughout the year, with the highest Catch Per Unit Effort (CPUE) reported for Oct. – Dec. Since this period aligns with the nesting season, most captured turtles are likely to be females. The high mortality rate reported in this study emphasizes the immediate threat posed by accidental captures to sea turtle populations, underscoring the critical importance of conservation efforts, particularly in artisanal gillnet fisheries.

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.

Two stranded Lepidochelys-like sea turtles were rescued from the Thai Andaman Sea coastline by veterinarians of the Phuket Marine Biological Center (PMBC), one in May of 2019 and another in July of 2021. They were first identified as olive ridley turtles (Lepidochelys olivacea), as the external appearance of both turtles was closer to that species than the other four species found in the Thai Andaman Sea. In fact, when carefully examined, an unusual pattern of the lateral scutes on each turtle was observed, specifically symmetric 5/5 and asymmetric 5/6, both of which are considered rare for L. olivacea and had never been reported in the Thai Andaman Sea. In contrast, this characteristic was more common for the closely related species, Kemp’s ridley (L. kempii), although this species is not distributed in the Indo-Pacific Ocean. Thus, we further investigated their genetic information to confirm species identification using two molecular markers, namely the mtDNA control region and nDNA RAG2. The results from the mtDNA control region sequences using the Basic Local Alignment Search Tool (BLAST) indicated that both individuals exhibited a higher percent identity with L. olivacea (99.81–100.00%) rather than L. kempii (94.29–95.41%) or any other species. A phylogenetic tree confirmed that these two turtles belonged to the L. olivacea clade. Moreover, the results of RAG2 also supported the mtDNA result, as both individuals shared the same RAG2 haplotype with L. olivacea. Thus, we have concluded that the two turtles with unusual lateral scute patterns exhibited genetic consistency with their original species, L. olivacea, which has brought attention to the importance of exploring rare phenotypes in sea turtle populations residing in Thai Seas.

Nesting events of loggerhead sea turtles (Caretta caretta) are on the rise in the Western Mediterranean Sea, far from their usual nesting areas in the Mediterranean and Atlantic basins. The study of dispersal behavior toward potential developmental areas of loggerhead post-hatchlings from this new nesting area is crucial to comprehend this colonization process and determining grounded conservation strategies. To fill this gap, we investigated, for the first time in the Mediterranean Sea, the dispersal strategies and habitat use based on data from 19 head-started loggerhead post-hatchlings released from the Spanish Mediterranean coast and satellite-tracked between 2016 and 2018. Turtles dispersed over large areas and showed active swimming phases, as they frequently dispersed against sea currents. Dispersal routes varied for each individual, although they consistently dispersed south-eastwards, especially during the coldest periods. Several post-hatchlings traveled through the Sicilian Channel to reach deep and warmer areas in the eastern Mediterranean basin. The most year-round suitable areas corresponded to the Ionian and Levantine Seas, which correspond with those found in their traditional nesting areas. Therefore, conservation measures focused on this stage should be taken in the path toward and these developmental areas. [ABSTRACT FROM AUTHOR]

Variation in sand composition at the individual beach level is an important factor for hatching success and hatchling phenotype that does not appear to have been previously investigated. We studied variation in intrabeach substrate composition in an important loggerhead turtle (Caretta caretta) nesting colony on the island of Maio, Cabo Verde, and examined its relationship with embryonic development success, hatchling phenotype, and hatchling vitality. Thirty-two nests from different females were studied under experimental conditions, controlling for beach position, depth, humidity, and temperature in a randomized block design. Two sand treatments corresponding to 2 types of sand from the same beach were used. While nesting females selected nesting sites indiscriminately between substrate types, their nests differed significantly in all variables measured for reproductive success (hatching success, hatchling size, and hatchling agility) between the 2 sand types. Therefore, the intrabeach observations of substrate phenotype of progeny found here could differentially affect offspring survival. The effects of choosing different nesting sites will generally act to spread the probability of selective pressures on embryos. Variation in reproductive success was due to differences between substrate types within the beach rather than the location of nests within the beach. The importance of determining sand types with the highest hatching success, even within the same beach, should be greatest in colonies or populations highly threatened with extinction, where the hatching success of each nest becomes of utmost importance. [ABSTRACT FROM AUTHOR]

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]

Small‐scale fisheries are a global conservation threat to marine megafauna (marine mammals, sea turtles, and elasmobranchs). There is currently limited information about marine megafauna catch in Thailand's small‐scale fisheries, which is required for effective management.This study represents the first independent catch assessment of marine megafauna in Thai small‐scale fisheries. Data on catch and fisheries effort across 1 year (2016–2017) were collected from questionnaire interviews with 535 fishers in 17 provinces along the Gulf of Thailand and the Andaman Sea coasts. Catch per unit effort was calculated for marine megafauna by fishing gear types and extrapolated to estimate annual catches using Thai official fisheries statistics.The annual estimated catches were 5.66 million (95% confidence interval, CI: 4.10–7.82 million) rays, 457,864 (95% CI: 192,352–969,166) sharks, 2,400 (95% CI: 1610–3,537) sea turtles, 790 (95% CI: 519–1,167) small cetaceans, and 72 (95% CI: 19–194) dugongs in Thai small‐scale fisheries.Gillnets had the highest catch per unit effort for all megafauna groups in both sea areas except for sea turtles, where pound nets had the highest catch per unit effort in the Gulf of Thailand. Further, among gillnets, crab gillnets had the highest catch per unit effort for all groups except dugongs, where ray gillnets had the highest catch per unit effort. Accounting for effort, crab gillnets and shrimp trammel nets were responsible for most of the megafauna catch, where crab gillnets contributed 72%–95% of the annual estimated marine megafauna catch. Crab gillnets and shrimp trammel nets were used by 46% and 40% respectively of the interviewed fishers and by 27% and 15% respectively of all small‐scale fishers operating in Thai waters.Restrictions for gillnet fishing effort (crab gillnets specifically) are needed to prevent extirpation of threatened megafauna species that are important for ecosystem resilience and productivity. [ABSTRACT FROM AUTHOR]

The olive ridley turtle (Lepidochelys olivacea) is the least studied sea turtle species, despite being the most abundant. Few studies on its diet have been reported worldwide, which suggest an omnivorous diet. The objective of this study was to characterize ontogenetic changes in diet composition and habitat use of the species in southern Brazil using gastrointestinal tract (GIT) contents and stable isotope (δ13C and δ15N) analyses. GITs (n = 10) and skin (n = 34) samples from specimens found stranded on the coast of Rio Grande do Sul (RS; from 31° 20′ S–51° 05′ W to 33° 45′ S–53° 22′ W) and individuals from incidental captures in the local bottom pair trawl fishery were collected from 2014 to 2019. Eighteen food items were found in the GITs, where the hermit crab Loxopagurus loxochelis had the highest contribution to the species diet, followed by the gastropod Buccinanops monilifer and the crabs Hepatus pudibundus and Libinia spinosa. Stable isotope mixing models showed the hermit crab as the most assimilated prey to juvenile and adult individuals, followed by a small contribution of salps to juvenile specimens. Prey preferences indicate a predominant use of the neritic environment for adults and a use of both neritic and oceanic environments for juvenile individuals. These results demonstrated that juvenile and adult olive ridley turtles use the coast of RS as a feeding ground; therefore, this area should be considered when proposing conservation measures for the species. [ABSTRACT FROM AUTHOR]

Sea Turtle Egg Fusariosis (STEF) is a worldwide emergent fungal disease affecting eggs and causing embryos mortality in turtle's nests such as those of Caretta caretta. It is caused by a complex of species belonging to Fusarium genus, particularly those included in the Fusarium Solani Species Complex (FSSC). During the samplings carried out in summer 2020 along the Tuscany coastlines (Italy), C. caretta eggs showed clinical signs resembling those caused by STEF. A total of 32 fungal isolates were obtained from lesioned eggs whose molecular characterization allowing identifying as belonging to FSSC / Neocosmospora spp., Fusarium oxysporum Species Complex (FOSC) / F. oxysporum and Fusarium nodosum , i.e., fungal genera and speciesincluding also well-known plant pathogens. Isolates inoculated on several plant hosts did not result in any pathogenic activity but F. nodosum causing, on wheat spikes, disease symptoms.This is the first time F. nodosum has been isolated from portions of eggs showing evident signs of fungal infection. This work represents the first report of Fusarium spp. isolated from C. caretta eggs showing lesions resembling those caused by STEF on Tuscan coast thus posing a significant concern to loggerhead sea turtle conservation also in this region. [Display omitted] • Fungal infectious diseases have dramatically increased in marine ecosystems. • STEF represent one of the main threats to Caretta in Mediterranean region. • A total of 32 strains of Fusarium strains were identified. • Phylogenetic relationships of Fusarium isolates have been reconstructed. • For the first time strains of F. nodosum were isolated from infected eggs. [ABSTRACT FROM AUTHOR]

The Guatemalan strategy for sea turtle conservation was defined by the National Council of Protected Areas (CONAP) in 1989. Hatcheries lie at the core of this strategy: egg collectors are allowed to deliver 20% of a nest to a hatchery in exchange for selling or eating the remaining eggs. Consequently, nearly 100% of nests are collected, with no nests being left on the beaches. Hatchery design promotes shading using roofs made from vegetation. The logic behind this recommendation is that the natural incubation of eggs is supposedly impossible due to the overly high temperatures on the beach. However, changing the incubation temperature of sea turtle eggs can profoundly alter the sex ratio in sea turtles with temperature-dependent sex determination. It can also modify the physiology or behavior of juvenile turtles. Here, we test whether incubation in natural conditions is possible on Guatemalan beaches, and for the first time, we determine the thermal reaction norm of embryo growth to ensure hatching success in sea turtles. We show that incubation in natural conditions is possible since three out of the four monitored nests produced hatchlings. We urge the Guatemala National Council of Protected Areas to reevaluate its strategy for sea turtle conservation in Guatemala in light of these results. [ABSTRACT FROM AUTHOR]

Passive acoustic and Argos satellite telemetry are common methods for tracking marine species and are often used similarly to quantify space use. However, data-driven comparisons of these methods and their associated ecological inferences are limited. To address this, we compared temporal durations, spatial resolutions, financial costs and estimates of occurrence and range distributions for each tracking approach using nine juvenile green turtles (Chelonia mydas) in Bimini, Bahamas. Tracking durations were similar, although acoustic tracking provided higher spatiotemporal resolution than satellite tracking. Occurrence distributions (95%) estimated from satellite telemetry were 12 times larger than those from acoustic telemetry, while satellite range distributions (95%) were 89 times larger. While individuals generally remained within the extent of the acoustic receiver array, gaps in coverage were identified. These gaps, combined with the lower accuracy of satellite telemetry, were likely drivers for the larger satellite distributions. Costs differed between telemetry methods, with acoustic telemetry being less expensive at larger sample sizes with a previously established array. Our results suggest that acoustic and satellite telemetry may not provide similar inferences of individual space use. As such, we provide recommendations to identify telemetry methods appropriate for specific study objectives and provide discussion on the biases of each.

BackgroundTranscriptomic 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.ResultsWe 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.ConclusionsObtaining 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.

This article, published in Frontiers in Marine Science, discusses the conservation implications of pathogens, parasites, and pollutants for sea turtles. The threats faced by sea turtles include interactions with fisheries, coastal development, direct take, climate change, pollution, and pathogens. The research highlighted in this article focuses on the impact of novel and emerging pathogens, pollutants, and parasites on sea turtles. The studies examine the effects of fungal diseases, mycobacteriosis, microplastics, and contaminants on sea turtle health and recovery. The findings contribute to our understanding of the threats to sea turtle populations and inform conservation efforts. [Extracted from the article]

As part of a sea turtle health monitoring program on the central east coast of Queensland, Australia, stranded and sick green sea turtles (Chelonia mydas) were subjected to necropsy and histopathology. A subset of these turtles had myocarditis of varying severity, which could not be attributed to parasitism by spirorchid flukes or bacterial infections. We, therefore, undertook an investigation to determine whether virus infections might be part of the pathogenesis. Deep sequencing revealed abundant DNA virus contigs in the heart tissue, of which CRESS and circoviruses appeared to be the most consistently present. Further analysis revealed the homology of some of the circoviruses to the beak and feather disease virus. While a causative link to myocarditis could not be established, the presence of these viruses may play a contributing role by affecting the immune system and overall health of animals exposed to pollutants, higher water temperatures, and decreasing nutrition.

Listeria monocytogenes is a ubiquitous pathogen found both in the environment and food. It can cause listeriosis in a wide range of animals as well as in humans. Investigations on presence, spread and virulence are still limited to terrestrial and human environments. Embracing the One Health Approach, investigating the presence and spread of L. monocytogenes in marine ecosystems and among wildlife, would provide us with useful information for human health. This study investigated the presence of L. monocytogenes and Listeria spp. in two species of sea turtles common in the Mediterranean Sea (Caretta caretta and Chelonia mydas). A total of one hundred and sixty-four carcasses of sea turtles (C. caretta n = 161 and C. mydas n = 3) stranded along the Abruzzo, Molise, Campania, and Calabria coasts, were collected. Brain and fecal samples were taken, enriched, and cultured for the detection of Listeria spp. From the specimens collected, strains of L. monocytogenes (brain n = 1, brain and feces n = 1, multiorgan n = 1 and feces n = 1), L. innocua (feces n = 1 and brain n = 1), and L. ivanovii (brain n = 1) were isolated. Typical colonies were isolated for Whole Genome Sequencing (WGS). Virulence genes, disinfectants/metal resistance, and antimicrobial resistance were also investigated. L. monocytogenes, L. innocua, and L. ivanovii were detected in C. caretta, whilst only L. monocytogenes and L. innocua in C. mydas. Notable among the results is the lack of significant differences in gene distribution between human and sea turtle strains. Furthermore, potentially pathogenic strains of L. monocytogenes were found in sea turtles.

IntroductionAn understanding of animal behavior is critical to determine their ecological role and to inform conservation efforts. However, observing hidden behaviors can be challenging, especially for animals that spend most of their time underwater. Animal-borne devices are valuable tools to estimate hidden behavioral states.MethodsWe investigated the fine-scale behavior of internesting hawksbill turtles using the mixed-membership method for movement (M4) which integrated dive variables with spatial components and estimated latent behavioral states.ResultsFive latent behavioral states were identified: 1) pre-nesting, 2) transit, 3) quiescence, and 4) area restricted search within and 5) near the residence of turtles. The last three states associated with a residency period, showed lower activity levels. Notably, when compared to other behaviors the pre-nesting exhibited shallower and remarkably long dives of up to 292 minutes. We noted high fidelity to residence core areas and nesting beaches, within and between nesting seasons, with residence areas decreasing within a season.DiscussionThe latent behaviors identified provide the most detailed breakdown of turtle movement behaviors during the internesting period to date, providing valuable insights into their ecology and behavior. This information can inform marine turtle conservation and management efforts since utilization distributions of individual behavioral states can be used to determine spatially-explicit susceptibility of turtles to various threats based on their behavior. The analyses of utilization distribution revealed a minimal overlap with existing marine protected areas (0.4%), and we show how a new proposal would expand protection to 30%. In short, this study provides valuable guidance for conservation and management of internesting marine turtles at a fine spatiotemporal resolution and can be used to enhance national action plans for endangered species, including the expansion of existing Marine Protected Areas. By flexibly incorporating biologically informative parameters, this approach can be used to study behavior outside of the hawksbill breeding season or even beyond this species.

Sea turtle nesting beaches are experiencing increased sand temperatures as climate change progresses. In one major green turtle (Chelonia mydas) nesting beach in the northern Great Barrier Reef, over 99 percent of hatchlings are female. The effects of contaminants on sea turtle hatchling sex determination are not often explored. Liver samples were collected from green turtle hatchlings that were sacrificed for histological sex determination in a parallel study on the effects of sand cooling on sex ratios, and analysed for trace elements via acid digestion and organic contaminants via in vitro cytotoxicity bioassays. Chromium, antimony, barium, and cadmium have previously been demonstrated to be estrogenic, and concentrations of these elements were used to calculate three estrogenic indexes for each clutch: predicted relative estrogenic potency (PEEQA), the sum of percent trace elements above the median of all samples (TEOM), and the sum of percent estrogenic elements above the median of all samples (EstroEOM). Excluding an outlier clutch, cadmium, antimony, and EstroEOM had significant positive relationships with sex ratio deviation. Mean clutch cobalt, lead, antimony and barium, also had a significant positive relationship with clutch sex ratio. There was no relationship between in vitro cytotoxicity of liver extracts and sex ratio, however, 9% of hatchlings had organic contaminants high enough to suggest potential cellular damage. Contaminant effects on sex determination are likely to be caused by a mixture of contaminant interactions as well as temperature. Many trace elements detected in this study have also been linked to negative health effects on hatchlings in previous studies. Considering the risks of feminization due to climate change and potential contaminant effects on hatchling health and sex determination, future studies exploring contaminant effects on sea turtle hatchling sex determination are recommended.