Green Turtle Chelonia Mydas Research Articles

Atlantic connectivity of a major green sea turtle Chelonia mydas foraging aggregation at the Banc d’Arguin, Mauritania

Understanding population connectivity is paramount for effective conservation. While genetic tools have elucidated sea turtle migration patterns, notable data gaps limit our understanding of ocean-wide connectivity, especially regarding east Atlantic green turtles. We characterized the genetic composition of a globally important green turtle foraging aggregation at the Banc d’Arguin, Mauritania, incorporating data from 323 individuals captured between 2018 and 2021. Using extended mitochondrial DNA D-loop (738 base pairs [bp]) and mitochondrial short tandem repeat (mtSTR; ~200 bp) markers, we assessed the genetic structure of Atlantic green turtle foraging aggregations and estimated the most likely origin of immature green turtles from the Banc d’Arguin using mixed stock analyses (MSAs). We identified 6 D-loop haplotypes, with a clear dominance of CM-A8.1 (91.8%) followed by CM-A5.1 (6.3%) and 4 rare haplotypes: CM-A1.4, CMA6.1, CM24.1 and CM36.1. We found 13 mtSTR haplotypes, with ‘7-12-4-4’ being dominant (89.0%). The genetic composition at the Banc d’Arguin differed significantly from the only foraging aggregation studied in West Africa to date—in the archipelago of Cabo Verde (located ca. 750 km from the Banc d’Arguin)—dominated by haplotype CM-A5. The MSA combining both genetic markers indicated that 87.6% of immature green turtles at the Banc d’Arguin originate from the major East Atlantic rookery at Poilão (Guinea-Bissau), but 11.6% come from more distant rookeries in South America (8.1%) and potentially Ascension Island (3.4%). We suggest that green turtle transatlantic movements may be more common than previously thought and highlight the importance of the Banc d’Arguin as a regional foraging hub for this species.

Two decades of community-based conservation yield valuable insights into marine turtle nesting ecology

AbstractFor 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.

Hawksbill and green turtle niche overlap in a marine protected area, US Virgin Islands

Studying how species interact with their environment and other co-occurring species are 2 main aspects of ecology. For marine turtles, ocean currents drive migratory routes and may determine the location of surrounding foraging grounds. As a result, circumglobal species like the hawksbill turtle Eretmochelys imbricata and green turtle Chelonia mydas adapt to diverse foraging habitats and employ varied feeding strategies. Dietary specializations may reduce competition for available food and space resources between co-occurring hawksbill and green turtles in US Virgin Island shallow reef habitats. This study analyzed isotopic data from immature hawksbill (n = 49; range: 18.7-49.8 cm straight carapace length [SCL]) and green turtles (n = 225; range: 24.1-69.4 cm SCL) to examine foraging niche. We used nitrogen stable isotope (δ15N) values as an indicator of trophic positioning and carbon stable isotope (δ13C) values as a habitat variable. Turtles were hand-captured across an 8 yr period (2012-2019), which facilitated the distinction of isotopic patterns in both the environment and among individual turtles. Understanding variations in habitat, community dynamics, and dietary consumption allowed us to utilize a 5 point framework to translate isotopic space to foraging niche. We found that the site’s relatively stable environmental conditions allow for isotopic overlap between hawksbill and green turtles despite the specialized feeding strategies each species employs. We also underscore the need to evaluate species-specific tissue turnover estimates as evidenced by the influence of tropical storms on recaptured turtle isotopic signatures. These findings inform our understanding of resource use for these imperiled species at our study site and are useful for future global isotopic comparisons.

From terra incognita to hotspot: the largest South Pacific green turtle nesting population in the forgotten reefs of New Caledonia

AbstractThe green turtle Chelonia mydas is a large marine turtle present in tropical and subtropical seas of the Atlantic, Pacific and Indian Oceans. It is categorized as Endangered on the IUCN Red List based on the trend of nesting populations at 32 sites, of which only three are in the Pacific Ocean. New Caledonia is a sui generis overseas territory of France in the south-west Pacific Ocean c. 1,210 km east of Australia. The presence of green turtles in New Caledonian waters is known, although the main nesting sites are far from the main island, on remote uninhabited islands. Since 1988 field missions to these remote reefs, namely d'Entrecasteaux, Bellona and Chesterfield, have collected data to quantify the nesting of green turtles in New Caledonia. For the first time we analyse the data collected during these missions. D'Entrecasteaux, Bellona and Chesterfield Reefs host a large nesting colony of green turtles, with the upper credible estimate of nesting activities reaching 150,000 nesting tracks in some years. These numbers exceed the estimated number of green turtle activities in the Pacific. The trend of the number of nesting activities is stable and has the same relationship with the Southern Oscillation Index as observed at Australian nesting sites. Our recommendations for the French authorities are to continue monitoring these populations, collect new demographic parameters and ensure the protection of these remote reefs, which should be considered a national treasure for New Caledonia.

Nowhere to hide: Sea turtle bycatch in Northwest Africa

Abstract 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.

Marine pollution between gyres: plastic debris in marine turtles and dolphins in French Guiana, Equatorial Atlantic

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.

Fibropapillomatosis Associated with Chelonid alphaherpesvirus 5 (ChHV5) in a Green Turtle Chelonia mydas in Argentine Waters.

Fibropapillomatosis is a debilitating neoplastic disease associated with Chelonid alphaherpesvirus 5 (ChHV5) infection. We detected the Atlantic variant of ChHV5 associated with a fibropapilloma in a green turtle (Chelonia mydas) found stranded on the western coast of Rio de la Plata, Argentina. This is the southernmost registered case for the southwestern Atlantic.

Microplastic Pollution in Sea Turtle Nests on the Beaches of Nautla and Vega de Alatorre, Veracruz

Microplastic contamination has become a topic of interest and concern worldwide due to its persistence and the possible effects it may cause to the environment. When microplastics are present, they can alter their physical properties, negatively affecting the surrounding fauna, such as sea turtles that use the beaches to nest in the sand. In this study, the exposure of sea turtle nests to microplastics on the beaches of Nautla and Vega de Alatorre, Veracruz, one of the main nesting areas for the green turtle Chelonia mydas, as well as Kemp’s ridley turtle Lepidochelis kempii from the Gulf of Mexico, was determined. Sand samples were obtained directly from the nests in situ on four beaches in the area and from two nesting pens, revealing the presence of microplastics in 100% of the nests in situ, with an average abundance of 2.43 ± 2.66 #MP/kg SS and a concentration of 0.00672 ± 0.02286 mgMP/kg SS, predominantly the form of foam, white in color, and from 1 to 2 mm in size.

Plasma hormone levels in the green turtle Chelonia mydas reared under captivity as a tool to predict mating and oviposition

Circulating estradiol (E2), testosterone (T) and progesterone (P4) concentrations, and blood chemistry were monitored in the female green turtle Chelonia mydas over continuous seasons at the Israel sea turtle breeding facility. The tested factors were analyzed with regard to the female`s nesting activity in the subsequent nesting season: Future nesters (FN) and Non-nesters (NN). Our analysis showed significant changes in all three sex steroids, E2, T, P4, and in 13 blood biochemical parameters between the two females` groups. All females presented consistent E2 profiles from year to year, with a single elevation in September in FN females. P4 concentrations in nesting females were high in April (mating) and higher towards the beginning of June due to oviposition, females that presented concentrations above 1ng/ml had successful oviposition (8 females: 1 female in 2018, 5 in 2019 and 2 in 2020). T profiles were high at the onset of vitellogenesis towards November and again high during April. We were able to predict which females would undergo oviposition with a specific profile seen only in FN females - elevated P4 concentrations from February to June and the elevation of metabolites electrolytes and Gamma-Glutamyl Transferase (GGT) concentrations toward November. This will facilitate selectively choice mating pairs to ensure that the Mediterranean population genetic variability is maintained. Clutches per female were between 2 and 6, with 25 in total. Females laid an average of 91 ± 7 eggs (range 39-139 eggs) per nest with emergence rate of ~10% (0-58%). Overall, the same trend in circulating steroid concentrations was revealed over the years in the females reaching oviposition only when a certain threshold was achieved. In this study all the factors mentioned above can indicate an upcoming oviposition at least 6 months prior to nesting as seen in the PCA analysis. This information can contribute to the success of green sea turtle breeding programs in captivity and will hopefully help the Israeli Rescue Center predict and prepare for nesting activities in the years ahead.

Seawater irrigation on nests can increase male marine turtle production

Global warming is increasing marine turtle nesting beach sand temperatures throughout the world. All marine turtles have temperature-dependent sex determination, with female hatchlings produced at warmer incubation temperatures. These warmer sand temperatures are causing a scarcity of male hatchlings at many nesting beaches. A range of mitigation strategies including shading and freshwater irrigation are being trialled at marine turtle nesting beaches around the world to address this issue. Because seawater is always abundant at marine turtle nesting beaches, we trialled a number of intense, one-off seawater irrigation experiments (equivalent to 100 and 200 mm rainfall) to test if male green turtle Chelonia mydas hatchling production could be increased without decreasing overall hatching success at Heron Island, southern Great Barrier Reef, Australia. We found that different combinations of seawater volume and temperature could produce a short-term drop in nest temperature by 2°C. When applied during the middle of embryonic development, these irrigation treatments could increase the proportion of male hatchlings compared to non-irrigated control nests, with less than a 10% decrease in hatching success. Hence, seawater irrigation has the potential to be a viable management strategy to increase the proportion of male marine turtle hatchlings at beaches that produce all, or nearly all, female hatchlings.

Recent decline of green turtle Chelonia mydas nesting trend at Tortuguero, Costa Rica

Trends in abundance of different life stages present important opportunities to manage the conservation of threatened species. For marine turtles, most trend assessments are based on long-term monitoring of nesting aggregations, which provides critical information on rookery dynamics across years. Tortuguero, Costa Rica, is the largest nesting colony of the green turtle Chelonia mydas in the Atlantic. Here we present an updated trend in annual clutch abundance spanning over 50 yr of monitoring at Tortuguero. We conducted weekly censuses recording clutch counts and used a generalized additive model (GAM) fitted for each monitored nesting season separately to predict daily tallies. We estimated annual clutch count as the sum of these. We modelled the long-term trend in annual clutch numbers with a Bayesian GAM with a cubic regression spline basis, fit to estimated annual clutch counts for 1971-2021. Finally, we examined spatio-temporal patterns in clutch counts along the beach by fitting a GAM with a 2-dimensional spline. Clutch estimates varied across years (78 695 ± 6727 [mean ± SE], range: 7004-186 640 clutches per year), but increased steadily over the first 37 yr. However, growth slowed gradually from 2000 to 2008, when the curve began to trend downwards. Tortuguero remains the largest aggregation of nesting green turtles within the Caribbean. Phenomena occurring across the population’s range and at several life history stages influence Tortuguero’s nesting trend. Thus, a decreasing trend at Tortuguero may be a warning sign for the Greater Caribbean green turtle metapopulation.

A dataset of sea turtle occurrences around the Taiwan coast.

We describe a dataset of sea turtle sightings around the coast of Taiwan and its islands (Hoh and Fong 2022). This data collection was initiated by TurtleSpot Taiwan, a citizen-science project that collects sea turtle sighting data. This dataset includes 3,515 sighting data dated from March 2010, except most of the data (n = 3,128; 89%) were collected between June 2017 to December 2021. Sightings were reported by citizen scientists to the Facebook Group of TurtleSpot Taiwan by providing occurrence information. We also requested photos and videos for species identification and to record any physical abnormality of the turtle, if observable. In addition to recording data often associated with an occurrence, TurtleSpot aims to identify each sea turtle up to the individual level using the Photo Identification (Photo ID) method. Hence, if photos of left facial scutes were available, the sighted individual can be identified and given a unique turtle ID. In total, 762 individuals were assigned a turtle ID, comprising 723 Greens (Cheloniamydas), 38 Hawksbills (Eretmochelysimbricata) and one Olive Ridley (Lepidochelysolivacea) turtle. This dataset is now publicly opened in Global Biodiversity Information Facility (GBIF) and available for download. It is hoped that the data may assist in future ecological studies and the development of conservation measures. This dataset contains 3,515 occurrence records of sea turtles (Cheloniidae) and is currently the largest public dataset of sea turtle sighting records in Taiwan. Post-publication of this dataset to the GBIF platform demonstrated that the number of Green sea turtle Cheloniamydas records in Taiwan is one of the largest in the world (last accessed date: 15-10-2022). The data served as the foundation for understanding biogeography and sea turtle ecology in Taiwan's coastal waters.

The toxic cosmopolitan cyanobacteriaMoorena producens: insights into distribution, ecophysiology and toxicity.

Moorena producens is a benthic filamentous cyanobacteria that has been widely documented for its toxicity. This cyanobacterium colonizes both temperate (37%) and tropical (63%) regions, making it a cosmopolitan cyanobacterium with a global distribution. M. producens grows across coral reefs in multiple locations but recurringly blooms in Queensland, Australia. Today, nuisance blooms of M. producens have resulted in major disruptions to recreational activities along coastal areas and are known to cause adverse effects on organism and human health upon contact or ingestion. Specifically, marine organisms such as the green turtle Chelonia mydas and hawksbill turtle Eretmochelys imbricata were fatally poisoned by M. producens after consumption of this cyanobacterium. Reports record a range of effects on human health, from pain and blistering or even death upon ingestion of contaminated seafood. Blooms of M. producens are triggered by influxes of nitrogen, phosphate and iron, from surrounding coastal runoffs or sewage effluents. Additions of these nutrients can result in an increase in growth rate by 4-16 times. Iron bioavailability also plays a crucial role in bloom formation. A total of 231 natural products from 66 groups were identified from M. producens, with the three dominant groups: malyngamides, microcolins and dolastatins. These bioactive secondary metabolites have displayed toxicities against a range of carcinoma cell lines and organisms such as brine shrimp Artemia salina and goldfish Carassius auratus. This review provides a thorough insight to the distribution, ecophysiology and toxicity of M. producens, with reports on bloom events and implications on organism and human health.

Lethal Lesions Caused by Propeller Cuts on the Endangered Green Turtle Chelonia mydas on Liuchiu Island, Taiwan

Green turtle (Chelonia mydas) is the most common sea turtle species in Taiwan. The coastal waters of Taiwan are known to contain foraging grounds for green turtles. Boat strike has been identified as the most common causes of sea turtle mortality in several sea turtle habitats worldwide. However, no relevant studies have investigated wild green turtles with boat strike injuries in Taiwan. In this field study, we conducted morphometric characteristics of 6 endangered green turtles (C. mydas) with boat strike injuries in Liuchiu Island of Pingtung County, Taiwan. This is the first report of its kind on the prevalence of documented boat strike lesions on stranded wild green turtles at their near shore foraging habitat. In 2019, a total of 14 stranded green turtles were dead when first found in Liuchiu Island of Pingtung County, Taiwan. Of these 14, 6 (42.8%) turtles showing evidence of propeller impacts. Conservation strategies including speed limits in key turtle neritic foraging habitats are required to improve their survival in Taiwan.

Bacterial and fungal pathogens in granulomatous lesions of Chelonia mydas in a significant foraging ground off southern Brazil.

The green sea turtle Chelonia mydas inhabit near-shore areas exposed to threatening anthropogenic activities. The granulomatous lesions in these animals may indicate infectious diseases that can be associated with environmental contamination and hazards to human health. This study aimed to characterize the granulomatous inflammation associated with bacterial and fungal infection in C. mydas off Paraná state. From September 2015 to February 2019, systematic monitoring was performed by the Santos Basin Beach Monitoring Project for sea turtles'carcasses recovery, necropsy, and cause of death diagnosis. The tissue samples were fixed in buffered formalin 10% for histochemical analysis and frozen for molecular analysis to fungi detection (Internal Transcribed Spacer region of the nuclear rDNA) and bacteria detection (16S ribosomal gene). From a total of 270 C. mydas, granulomatous lesions were observed in different organs of 63 (23.3%) individuals. The histological analysis indicated lesions in 94 organs, affecting most respiratory and digestive systems. Bacteria were identified in 25 animals, including an acid-fast bacteria detected in one animal, and fungi in 24 C. mydas. The fungi species included the genus Candida (Candida zeylanoides, n = 3), Yarrowia (Yarrowia lipolytica, n = 9; Yarrowia deformans, n=5; and Yarrowia divulgata, n = 1), and Cladosporium anthropophilum (n = 1). No species of bacteria was identified by molecular testing. All fungi species identified are saprobic, some are important to food and medical industries, but are also pathogens of humans and other animals. Therefore, long-term monitoring of these pathogens and the C. mydas health may indicate changes in environmental quality, possible zoonotic diseases, and their effects.

The island hoppers: how foraging influences green turtle Chelonia mydas abundance over space and time in the Lakshadweep Archipelago, India

Adult green turtles are known to display either preference in their foraging habits or fidelity to their foraging sites which, in turn, influences their migrations and the availability of forage. With an abundant supply of seagrass and algae, the lagoons of the Lakshadweep Archipelago off the Indian west coast serve as significant feeding grounds for green turtles. In the last 2 decades, the numbers of foraging green turtles have varied across islands, leading to speculation about their foraging patterns and movements. We collated secondary data and conducted periodic surveys between 2013 and 2019 to record trends in green turtle abundance and seagrass characteristics and investigate relationships between them. Over the last decade, green turtle abundances have fluctuated widely with increases followed by sharp declines within different lagoons. Our results also show that a reduction in seagrass density, particularly Thalassia sp. and Cymodocea sp., coincided with the decline in green turtle abundance. Moreover, turtle presence was observed at sites with higher seagrass density and canopy height. Our findings indicate that green turtles appeared to forage in particular lagoons until their preferred resources declined, before moving to other islands within the Archipelago or other unknown locations. Therefore, to devise effective management strategies, it is crucial to understand how this green turtle population will adapt to the decline in foraging resources. The declining seagrass populations also suggest the need for an ecosystem approach towards green turtle conservation.

Abundance Trends and Nesting Biology of Green Turtles Chelonia mydas (Testudines: Cheloniidae) During Ten Consecutive Breeding Seasons (2012-2021) at Akyatan Beach, Turkey.

Data obtained from long-term survey studies are valuable for assessing the population status and trends in critical populations of threatened species, like sea turtles. Akyatan Beach is one of the most important green turtle nesting beaches in the Mediterranean and has been monitored since 2006 without interruption. The beach is 22 km long and more than 100 m wide at some points, and both loggerhead and green turtles nest on the beach. However, loggerhead nesting is very limited compared to green turtles. A total of 3866 C. mydas nests were recorded over ten consecutive years at Akyatan Beach, with a mean of 387 ± 127 nests (range = 201-559). The average nesting density was 17.6 nests km-1 (range = 9.1-25.4 nests km-1). In the 3309 nests, a total of 355,259 eggs were counted. The overall mean clutch size was 112 ± 26.10 eggs. Of these eggs, 50.80% hatched (depredated nests included), and 78.07% of them were able to reach the sea. The overall mean hatching success was 73.07 ± 26.20%. The overall mean incubation duration was 51.4 ± 3.5 days. The clutch sizes and hatching success differed between years, and there was a significant decreasing trend in mean incubation duration over the ten years of the study. A total of 1585 green turtle nests (41.02% of nests) were totally or partially depredated by golden jackals and wild boars, while other predators depredated 20.5% of hatchlings. The nesting data obtained since 2006 showed strong annual fluctuations ranging from 170 (in 2007) to 562 (in 2006) with a slightly increasing but statistically insignificant trend (r = 0.94, p > 0.05). The main threats to the population were depredation by jackals and wild boars.

Plastic ingestion by juvenile green turtles (Chelonia mydas) off the coast of Southern Brazil

Five of the seven extant sea turtle species in the world forage on the coast of Southern Brazil at least in some stage of their life cycle. The green turtle Chelonia mydas frequently strands on beaches of Rio Grande do Sul State. The species is currently classified as vulnerable to extinction in the region, and pollution by marine debris is one of the most conspicuous threats to its conservation. In this study, we quantified and characterized plastic ingestion by juvenile green turtles in waters off the southern Brazilian coast between 2013 and 2016. We analysed the gastrointestinal content of 17 beached carcasses and registered debris ingestion in 15 individuals (88%). On average, each green turtle ingested 38.4 ± 88.5 plastic fragments. White and transparent plastic bags and plastic sheets were predominant. Our results indicate a high interaction between juvenile green turtles and marine debris off the coast of Southern Brazil.

Distribution and toxicity of persistent organic pollutants and methoxylated polybrominated diphenylethers in different tissues of the green turtle Chelonia mydas.

Investigating environmental pollution is important to understand its impact on endangered species such as green turtles (Chelonia mydas). In this study, we investigated the accumulation and potential toxicity of selected persistent organic pollutants (POPs) and naturally occurring MeO-PBDEs in liver, fat, kidney and muscle of turtles (n=30) of different gender, size, year of death, location and health status. Overall, POP concentrations were low and accumulation was highest in liver and lowest in fat which is likely due to the poor health of several animals, causing a remobilization of lipids and associated compounds. PCBs and p,p'-DDE dominated the POP profiles, and relatively high MeO-PBDE concentrations (2'-MeO-BDE 68 up to 192ng/g lw, 6-MeO-BDE 47 up to 79ng/g lw) were detected in all tissues. Only few influences of factors such as age, gender and location were found. While concentrations were low compared to other marine wildlife, biological toxicity equivalences obtained by screening the tissue extracts using the micro-EROD assay ranged from 2.8 to 356pg/g and the highest values were observed in muscle, followed by kidney and liver. This emphazises that pollutant mixtures found in the turtles have the potential to cause dioxin-like effects in these animals and that dioxin-like compounds should not be overlooked in future studies.

Role of incubation environment in determining thermal tolerance of sea turtle hatchlings

Warming global temperatures are predicted to reduce population viability in many oviparous ectothermic taxa, with increased embryonic mortality likely to be a main cause. While research on embryonic upper thermal limits is extensive, sea turtle hatchling thermal tolerance has received less attention and our understanding of how incubation conditions influence hatchling thermal tolerance is limited. Here, we report green turtle Chelonia mydas hatchling hydration and thermal tolerance following incubation in dry and wet conditions. We used packed cell volume and total protein as indicators of hydration and measured the critical thermal maximum (CTmax) of hatchlings in air. Neither hydration nor thermal tolerance was directly influenced by moisture treatment. However, hatchlings from moister nests had longer incubation durations (wet: 60.11 d vs. dry: 54.86 d), and, using incubation duration as a proxy for incubation temperature, hatchlings from cooler nests had significantly lower CTmax (wet: 39.84°C vs. dry: 40.51°C). Thus, despite not directly influencing thermal tolerance, moisture treatment influenced nest temperature indirectly; hatchlings that experienced warmer conditions in dry nests had a higher thermal tolerance than hatchlings from cooler and wetter nests. Ectothermic neonates may have greater plasticity in their thermal tolerance than previously thought, but their ability to adapt to increasing temperature is likely limited. Additionally, common management techniques to reduce nest temperatures, such as watering and shading nests, may only reduce embryonic mortality at the cost of decreased hatchling thermal tolerance and increased hatchling mortality during emergence. Nesting-site management interventions designed to reduce embryonic mortality will need to consider mitigation of the possible effects of those interventions on hatchling mortality.