Northwest Atlantic leatherback (Dermochelys coriacea) sea turtle populations are endangered and have low hatching success compared to other sea turtles. Hatchling survival is an important element of their conservation. This longitudinal study assessed developmental phase and pathology of leatherback embryos and hatchlings at Sandy Point National Wildlife Refuge (SPNWR) on St. Croix, US Virgin Islands, in 2019 to identify patterns in mortality and lesions across a nesting season, and to make regional comparisons. Hatching and emergence success averaged 63.6% and 56.6%, respectively, and both differed significantly by month. 'Breakout' analysis was conducted on 41 nests and showed a preponderance of unhatched eggs lacking grossly evident embryological development (52%). Necropsies were performed on 79 unhatched and dead in nest individuals from 34 nests, and most (58%) had lesions including inflammation associated with micro-organisms (34%), renal mineralization (15%), mild multifocal skeletal muscle degeneration and necrosis (5%), and anatomic malformations (4%). Inflammatory lesions included chorioallantoitis, esophagitis, stomatitis, dermatitis, gastritis, and yolk sacculitis. These were associated with bacteria (n = 13), fungi (n = 4), or both (n = 7). Sex was determined histologically and was predominantly female (90%) with no males identified in nests laid after 3 April 2019. Although hatching success was higher in in situ relative to relocated nests, embryological development and lesion patterns were similar in both groups. Patterns of lesions observed in leatherback embryos and hatchlings did not differ across the season and are comparable to other Caribbean nesting sites. Future studies pairing 'breakout' and pathological analyses with assessments of potentially influential environmental and/ or maternal factors could help develop targeted strategies for improving hatchling production.
Strategies to improve the hatch success and survival of critically endangered hawksbill turtles (Eretmochelys imbricata) require knowledge of threats to them including pathological conditions. The objective of this study was to describe the mortality and pathology of embryos and dead-in-nest hatchlings on St. Kitts and Nevis. Over the 2019/20 and 2020/21 nesting seasons, the combined mean (SD) hatch success for the two islands was 81.9% (13.2%) and deceased individuals within excavated nests were early-stage embryos (70.7%), late-stage embryos (17.7%), pipped-hatchlings (8.2%) or dead-in-nest hatchlings (3.4%). From 2017 to 2021, a post-mortem examination was performed on 183 turtles, including histology for 116. Anatomical malformations affected 77 (42.1%) examined turtles and included abnormal scute shape or number (22.4%), dysmelia (8.7%), schistosomus reflexus (7.7%) and compressed carapace (7.7%). Microscopic lesions were found in 49.1% of turtles and included tissue mineralization (26.7%, including renal, fetal membrane, liver, heart or muscle), chorioallantoitis (16.2%) and skeletal muscle degeneration and necrosis (10%). Inflammatory lesions associated with fungal or bacterial infections were in the skin (n = 3), chorioallantois (n = 4), lung (n = 3) or yolk sac (n = 1). These lesions may reflect non-specific terminal conditions but their presence in-nest helps explain some of the mortality and pathology documented in hatchlings that die during rehabilitative care. All of the gonads adequately represented for histological determination of sex were female (n = 62), supporting concern for feminization of Caribbean hawksbill turtle nests. The study identifies lesions that could affect hatch and emergence success. The high frequency of skeletal malformations indicates the need for investigations addressing regional impact and pathogenesis, especially genetic and environmental aetiologies including nest temperature. Immediate examination of live hatchlings on nest emergence is warranted to better determine the prevalence of non-fatal malformations that could impact fitness and population genetics.
Historically, juvenile and subadult green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) sea turtles have been observed in the waters surrounding St. Kitts, West Indies, year-round; however, no formal population or health assessment for these species and cohorts in St. Kitts has been previously conducted. During the study period (2004–2017), 211 juvenile sea turtles (158 hawksbills and 53 greens) were captured at 16 different capture sites in St. Kitts. Once turtles were on shore and restrained, morphometric measurements and mass were collected, untagged animals were tagged, and a health assessment was performed. Blood samples were collected and used to establish reference intervals for hematological and biochemical parameters. These reported reference intervals make it possible to incorporate monitoring programs for infectious diseases and to identify any trends in population and health status. The morphometrics, mass, and number of animals captured enable sound decision-making as it relates to conservation policy development and implementation, which is especially important in countries such as St. Kitts and Nevis where an open harvest for sea turtles still exists.
Increasing hatchling survival is an important element of conservation of the critically endangered hawksbill sea turtle (Eretmochelys imbricata). Yet, there is little information regarding mortality-associated pathological states of hawksbill hatchlings. The aim of this study was to describe lesions affecting hawksbill hatchlings that died while under rehabilitative care. Forty-four turtles representing the nesting sites of two islands and a 7-yr study period were subjected to comprehensive postmortem examination. The most common lesions included dermatitis (34%), skeletal malformations (23%), and pneumonia (23%). Dermatitis and pneumonia were caused by a variety of presumptively opportunistic bacterial and fungal infections. Fungal infections affected 23% of study turtles, also causing rhinitis and esophagitis. Around half of the cases of dermatitis presented with history of skin lesions, and all those involving periocular areas had clinical history of eye lesions. Pneumonia was not predicted by clinical signs or time in rehabilitation. Malformations included carapace compressions, supra- or subnumerary scutes, and dysmelias with many of those affected having concurrent pathology involving other organs. Other lesions included bacterial yolk sacculitis (15%), skeletal muscle degeneration and necrosis (13%), and acute renal tubular necrosis (13%). The study population was female biased (93%), raising concern for skewed hatchling sex ratios and high incubation temperatures in the eastern Caribbean. The pathology described by this study improves our understanding of threats to hawksbill hatchlings and may be taken into consideration by clinicians when implementing strategies for rehabilitative care.
To date, only a handful of viruses have been identified in sea turtles. Although eukaryotic circular Rep (replication initiation protein)-encoding single-stranded DNA (CRESS DNA) viruses have been reported from a wide variety of terrestrial species, and some of these viruses have been associated with clinical conditions in certain animals, limited information is available on CRESS DNA viruses from marine life. The present study aimed to investigate the presence of CRESS DNA viruses in sea turtles. In the present study, two (samples T3 and T33) of the 34 cloacal samples from 31 sea turtles (found in ocean waters around the Caribbean Islands of St. Kitts and Nevis) tested positive for CRESS DNA viruses by a pan-rep nested PCR assay. The partial Rep sequence of T3 shared 75.78% of a deduced amino acid (aa) identity with that of a CRESS DNA virus (classified under family Circoviridae) from a mollusk. On the other hand, the complete genome (2428 bp) of T33 was determined by an inverse nested PCR assay. The genomic organization of T33 mirrored those of type II CRESS DNA viral genomes of cycloviruses, characterized by the putative "origin of replication" in the 5'-intergenic region, and the putative Capsid (Cap)- and Rep-encoding open reading frame on the virion-sense- and antisense-strand, respectively. The putative Rep (322 aa) of T33 retained the conserved "HUH endonuclease" and the "super 3 family helicase" domains and shared pairwise aa identities of ~57% with unclassified CRESS DNA viruses from benthic sediment and mollusks. Phylogenetically, the T33 Rep formed a distinct branch within an isolated cluster of unclassified CRESS DNA viruses. The putative Cap (370 aa) of T33 shared maximum pairwise aa identity of 30.51% with an unclassified CRESS DNA virus from a capybara. Except for a blood sample from T33 that tested negative for CRESS DNA viruses, other tissue samples were not available from the sea turtles. Therefore, we could not establish whether the T3 and T33 viral strains infected the sea turtles or were of dietary origin. To our knowledge, this is the first report on the detection of CRESS DNA viruses from sea turtles, adding yet another animal species to the rapidly expanding host range of these viruses. Complete genome analysis of T33 identified a novel, unclassified CRESS DNA virus, providing insights into the high genetic diversity between viruses within the phylum Cressdnaviricota. Considering that sea turtles are an at-risk species, extensive studies on virus discovery, surveillance, and pathogenesis in these marine animals are of the utmost importance.
The St. Kitts Sea Turtle Monitoring Network (SKSTMN) began implementation of a leatherback sea turtle (Dermochelys coriacea) monitoring program in 2003 on the main leatherback nesting beaches on St. Kitts, Keys Beach, and North Friars Beach, West Indies. From March 2003 to July 2016, a total of 2,419 adult female leatherback emergence events were recorded and evaluated. A notable decrease in adult leatherback emergence activity was observed over the course of the study period. The nesting season was documented to range from February to August. April and May were typically the months with the highest frequency of nesting. The number of females individually identified (flipper tagging and/or passive integrated transponder) from 2004–2016 was 259, with a mean curved carapace length (CCL) (n = 720) of 153 cm and mean curved carapace width (CCW) (n = 719) of 113 cm. Remigration intervals ranged from 1–5 yr with a median of 2 yr. For nesting females in St. Kitts over the course of the study period, mean clutch frequency (with standard deviation [SD]) was 3 (SD 2.9) and during a reproductive season was 2.2 (SD 1.44). Mean total number of eggs laid per nest was 113 with mean number of yolked eggs being 83.5 and yolkless 29.3. The mean incubation period was 59.5 days overall (SD 3.5) with a hatch success overall of 16.75%. Relocated nests had significantly lower hatch success than in situ nests and poaching rates decreased over the course of this study. From 2006–2016, a total of 191 blood samples were collected from 118 individual animals. Hematological and plasma biochemical parameters are outlined and changes in values in individuals over the course of nesting seasons and association with remigration intervals are described. The goal of this study was to report on 14 years of leatherback monitoring and determine the baseline health profile of the nesting leatherback population in St. Kitts.
Globally, the hatch success of leatherback sea turtles (Dermochelys coriacea) is much lower than any other sea turtle species. Causes of embryonic mortality, a contributing factor to the low hatch success of the species, are poorly understood. Muscle necrosis, renal mineralization, and bacterial pneumonia are prevalent among embryos and hatchlings in St. Kitts, where hatch success is much lower (< similar to 20%) than the global average (similar to 50%), yet the significance of these conditions in the wider region is unknown. The objective of this study was to describe the pathology of hatchlings and embryos in Grenada as a comparison population for St. Kitts. In 2017, 20 hatchlings, 6 pipped hatchlings, 35 late stage embryos, and 5 early stage embryos were sampled for comprehensive postmortem examination from 12 leatherback nests on Levera Beach, Grenada and 2 nests on St. Kitts. Pathology affected 71% of nests and 44% of individuals from Grenada and 100% of nests and 56% of individuals from St. Kitts. Lesions observed in both populations included skeletal muscle degeneration and necrosis (19%), bronchopneumonia (8%), and renal tubular degeneration (5%) while chorioallantoitis (17%) and mycotic dermatitis (5%) were only observed in Grenada. Gonads were histologically classified as female in all instances (n = 60), suggestive of high incubation temperatures in nests at both locations. Further study is needed to find interventions that reduce the prevalence of perinatal pathology and to identify the basis for the large proportion of eggs that fail to develop as well as embryos that die without significant pathology.
Northwest Atlantic leatherback sea turtles (Dermochelys coriacea) are endangered and low hatch success limits potential for population recovery. We examined essential and nonessential metal concentrations in 43 eggs from nests on St. Kitts to determine if there was a relationship with hatch success. Whole homogenized embryos and undeveloped eggs contained detectable concentrations of arsenic, barium, copper, iron, selenium, vanadium, and zinc, but not beryllium, cadmium, chromium, cobalt, lead, mercury, molybdenum, and thallium. Of detected metals, only vanadium concentrations negatively correlated with hatch success (P = 0.01). Manganese and vanadium were associated with pneumonia occurring in the nest, and arsenic with renal mineralization. This study adds to the knowledge regarding baseline values for environmental contaminants in sea turtles, supporting the trend that leatherback eggs have relatively low concentrations of toxic metals, lacking a strong relationship with hatch success, and normally contain the essential elements copper, iron, selenium, and zinc.
Sustained hatchling production is a priority for leatherback sea turtle (Dermochelys coriacea) conservation. Yet the species is challenged by notoriously low hatch success, much lower than other species of sea turtles, and the result of a high rate of embryo mortality for which the causes are not understood. The aim of our study was to describe the pathology of embryos and dead-in-nest hatchlings, to help understand the basis for low hatch success in St. Kitts, West Indies. We surveyed two leatherback nesting beaches, Keys and North Friars, in 2015-16. Pathology was present in 38% (32 of 84) of individuals, including renal mineralization (24%, 20 of 83), bacterial pneumonia (12%, 10 of 82), and skeletal muscle necrosis (7%, 6 of 84). Renal mineralization was seen in all stages of development that we examined and was associated with cardiac mineralization in two cases. Bacterial pneumonia affected dead-in-nest hatchlings and late-stage embryos and involved 40% (6 of 15) of nests evaluated, all laid by different mothers. Hematopoiesis was consistently observed in the liver, lung, kidneys, and heart. Gonad was histologically classified as female in 100% (68 of 68) of individuals examined. Rathke's gland was identified in the axillary musculature of 51 individuals, which has not previously been described in leatherbacks. Bacterial pneumonia and renal mineralization were presumed to be significant causes of death in leatherback embryos and hatchlings in St. Kitts. Overrepresentation of females in our study suggested high incubation temperatures in the nests.
To address some of the threats facing sea turtles in St. Kitts, the St. Kitts Sea Turtle Monitoring Network (SKSTMN) has implemented a number of conservation education programs. The primary conservation education program has been an annual Sea Turtle Camp Program that was developed and initiated in 2007 with the goal of engaging and educating youth in the conservation of sea turtle species. In 2015 and 2016, the SKSTMN performed an assessment of this education program. The outcome assessment included 1) evaluation of pre- and postparticipation tests for the 2015 and 2016 participants, 2) comparison with a control group of nonparticipants who took the posttest, and 3) a survey of former participants and their parents or guardians. The pre/post exercise was performed to determine if students were gaining and retaining information during the Sea Turtle Camp Program and if participants had a stronger knowledge base than nonparticipants. The survey of former participants was performed to determine if this program had positively affected participants and their perceptions regarding sea turtles, the marine environment, and conservation; to ascertain strengths and weaknesses of the Sea Turtle Camp Program; and to identify conservation education areas that could be further developed. The results obtained for participants in the Sea Turtle Camp Program between the pre- and posttests indicated that the educational modalities used are successfully relaying the desired information and that the majority of the participants are retaining this information throughout the Sea Turtle Camp Program. Additionally, the results on the pre- and posttests for the Sea Turtle Camp Program participant group vs. the control group of nonparticipants indicate that the Program had a significant impact on participant's knowledge regarding sea turtle natural history, biology, and St. Kitts-specific sea turtle issues. Findings indicated that there were positive changes in behavior toward the marine environment and sea turtles in Sea Turtle Camp participants following participation and that there was a need for additional curriculum to be developed to accommodate former participants who were interested in continuing their participation in the program.
Along the West Coast of Barbados a unique relationship has developed between endangered green sea turtles (Chelonia mydas) and humans. Fishermen began inadvertently provisioning these foraging turtles with fish offal discarded from their boats. Although initially an indirect supplementation, this activity became a popular attraction for visitors. Subsequently, demand for this activity increased, and direct supplementation or provisioning with food began. Food items offered included raw whole fish (typically a mixture of false herring [Harengula clupeola] and pilchard [Harengula humeralis]), filleted fish, and lesser amounts of processed food such as hot dogs, chicken, bread, or various other leftovers. Alterations in behavior and growth rates as a result of the provisioning have been documented in this population. The purpose of this study was to determine how tourism-based human interactions are affecting the overall health of this foraging population and to determine what potential health risks these interactions may create for sea turtles. Juvenile green sea turtles (n = 29) were captured from four sites off the coast of Barbados, West Indies, and categorized into a group that received supplemental feeding as part of a tour (n = 11) or an unsupplemented group (n = 18) that consisted of individuals that were captured at sites that did not provide supplemental feeding. Following capture, a general health assessment of each animal was conducted. This included weight and morphometric measurements, a systematic physical examination, determination of body condition score and body condition index, epibiota assessment and quantification, and clinical pathology including hematologic and biochemical testing and nutritional assessments. The supplemented group was found to have changes to body condition, vitamin, mineral, hematologic, and biochemical values. Based on these results, recommendations were made to decrease negative behaviors and health impacts for turtles as a result of this provisioning.
The St. Kitts Sea Turtle Monitoring Network (SKSTMN) is a community-based sea turtle conservation organization operating in St. Kitts, West Indies. Four species of either nesting and/or foraging sea turtles have been recorded in the area around St. Kitts, including leatherback (Dermochelys coriacea), green (Chelonia mydas), hawksbill (Eretmochelys imbricata), and loggerhead (Caretta caretta). An open fishing season for sea turtles is active in St. Kitts and Nevis from 1 October through 28 February annually. In 2006, sea turtle fishers in St. Kitts were assessed by the SKSTMN through a survey process to determine the status of sea turtle stocks in the St. Kitts area and to determine the feasibility of developing a local community-based ecotourism project focusing on sea turtles. Based on the results of this survey, the SKSTMN made the decision to develop alternative livelihoods for the fishers to serve as a replacement for the harvest. These included a Sea Turtle Technician Program and a St. Kitts Leatherback Ecotour Package. Prior to the development and implementation of the St. Kitts Leatherback Ecotour Package, a representative survey was prepared and distributed to 3 target groups: local citizens, tourists, and residents. A complete tour package was developed according to the survey results, and the package was offered during leatherback nesting seasons from 2009 to 2014. In 2014, an outcome assessment of the ecotourism initiative was conducted that consisted of electronic survey delivery to a subset of former ecotour participants. These initiatives have resulted in a decrease in the number of sea turtles harvested in St. Kitts annually and have also produced a number of sustainable technician positions for Kittitian citizens on the project.
A severely debilitated juvenile green sea turtle (Chelonia mydas) was discovered floating in the Caribbean Sea off the coast of St. Kitts and Nevis on 07 September 2012. The animal was rescued and presented to the St. Kitts Sea Turtle Monitoring Network (SKSTMN) for evaluation. On arrival to the Ross University School of Veterinary Medicine (RUSVM) Chelonian Laboratory, the turtle was lethargic but alert and responsive. On physical examination, the turtle weighed 5.5 kg, with a body condition score of 2/5; exhibited moderate dehydration; moderate to severe generalized edema; and a diffuse separation of the carapacial scutes from bone with the marginal scutes being affected more severely. The turtle’s epibiota load was moderate and included algae, barnacles, leeches, and a parasitic worm. Abnormal findings from a complete blood count (CBC) and plasma biochemistry panel were anemia, leukopenia, hypoproteinemia, hypoalbuminemia, and hypoglycemia. There was an inverse Ca : P ratio and both aspartate aminotransferase (AST) and creatine kinase (CK) were elevated. The turtle was voiding urine but no feces. Figure 1. Dorsoventral radiograph of a juvenile green sea turtle.
Salmonella spp. are gram-negative bacteria capable of causing diseases in a wide range of aquatic and terrestrial animals, including humans. Sea and terrestrial turtles have been recognized as carriers of this zoonotic pathogen. In this project, conventional and molecular diagnostic methods were combined to investigate the prevalence of Salmonella enterica in leatherback sea turtles (Dermochelys coriacea) that used the island of St. Kitts, West Indies as a nesting ground during 2011 (n = 21). Isolates obtained from selective media were screened and colonies suspected of being Salmonella spp. were confirmed by fluorescence resonance energy transfer polymerase chain reaction. The prevalence of S. enterica within this sample population during this period was found to be 14.2%. Moreover, due to the increasing risk of antibiotic resistance in enteric bacteria, antimicrobial susceptibility was investigated in all recovered Salmonella spp. isolates utilizing the broth microdilution method. All isolates were susceptible to the lowest concentration of kanamycin, gentamicin, ciprofloxacin, enrofloxacin, nalidixic acid, and trimethoprim/sulfamethoxazole tested. Further research should be pursued to understand the interaction of this bacterial pathogen with the environment, host, and other microbial communities, and to further develop faster, more sensitive, and more specific diagnostic methods.
Conservation programs to protect endangered sea turtles are being instituted worldwide. A common practice in these programs is to collect blood to evaluate the health of the turtles. Several different venipuncture sites are used to collect blood from sea turtles for hematologic and biochemistry tests, depending on the species. To date, it is unknown what affect venipuncture site may have on sample results. The purpose of this study was to measure the level of agreement between hematologic and biochemistry values collected from the dorsal cervical sinus and the interdigital vein of leatherback (Dermochelys coriacea) sea turtles. Paired heparinized blood samples were obtained from the dorsal cervical sinus and the interdigital vein of 12 adult female nesting leatherback sea turtles on Keys Beach, St. Kitts, West Indies. Even though the sample population was small, the data for each chemistry were normally distributed, except for creatine kinase (CK). There was no significant difference when comparing biochemistry or hematologic values by venipuncture site, except for CK (P = 0.02). The level of agreement between sampling sites was considered good for albumin, calcium, globulin, glucose, packed cell volume, phosphorus, potassium, sodium, total protein, total solids, uric acid, white blood cell count, and all of the individual white cell types, while the level of agreement for aspartate aminotransferase and CK were considered poor. This information, coupled with the fact that the interdigital vein affords a less-invasive procedure, demonstrates that the interdigital vein is an appropriate location to use when establishing a hematologic and biochemical profile for leatherback sea turtles.