Hawksbill Research Articles

Quantifying Illegal Extraction of Sea Turtles in Costa Rica

Estimates of illegal wildlife trade vary significantly and are often based on incomplete datasets, inferences from CITES permits or customs seizures. As a result, annual global estimates of illegal wildlife trade can vary by several billions of US dollars. Translating these figures into species extraction rates is equally challenging, and estimating illegal take accurately is not achievable for many species. Due to their nesting strategies that allow for census data collection, sea turtles offer an exception. On the Caribbean coast of Costa Rica, three sea turtle species (leatherback,Dermochelys coriacea;green,Chelonia mydas; and hawksbill,Eretmochelys imbricata) are exploited by poachers. Despite the consumption of turtle eggs and meat being illegal, they are consumed as a cultural food source and seasonal treat. Conservation programmes monitor nesting beaches, collect abundance data and record poaching events. Despite the availability of robust long-term datasets, quantifying the rate of poaching has yet to be undertaken. Using data from the globally important nesting beach, Tortuguero, as well as beaches Playa Norte and Pacuare on the Caribbean coast of Costa Rica, we modelled the spatial and temporal distribution of poaching of the three sea turtle species. Here, we present data from 2006 to 2019 on a stretch of coastline covering c.37 km. We identified poaching hotspots that correlated with populated areas. While the poaching hotspots persisted over time, we found poaching is declining at each of our sites. However, we urge caution when interpreting this result as the impact of poaching varies between species. Given their low abundance on these beaches, the poaching pressure on leatherback and hawksbill turtles is far greater than the impact on the abundant green turtles. We attribute the decline in poaching to supply-side conservation interventions in place at these beaches. Finally, we highlight the value of data sharing and collaborations between conservation NGOs.

Understanding the coastal erosion vulnerability influence over sea turtle (Eretmochelys imbricata) nesting in NE of Brazil

Most of the studies on sea turtle nesting activity nowadays are focused on the impacts of climate change. However, there is a lack of studies gathering knowledge about the influence of coastal vulnerability to erosion and settlement to assess sea turtle nesting. This study aims to verify the influence of coastal erosion vulnerability over sea turtle nesting in five Brazilian Northeast beaches, in Pernambuco state, at Ipojuca coast. The main analyzed parameters were the urban settlement, coastal erosion indicators and the conservation status of the dunes by assessing shoreline change rates, backshore extension, vegetation cover and beaches morphodynamics associated aspects. Spearman’s rank correlation coefficient and tests of Kruskal–Wallis, Mann–Whitney, Shapiro–Wilk and Levene were employed as a set of statistical analyses. The results state that Eretmochelys imbricata is the predominant species that nests at the Ipojuca coast (93.2% of nesting females). There is a significant difference in the number of nests among the studied beaches (Kruskal–Wallis; p = 0.004). A strong and positive correlation between the backshore width and the number of nests was verified (Spearman’s rank correlation, rs = 0.881; p = 0.0002). The results indicate the preference for nesting on wave-dominated beaches, where the coastal reefs are absent and there is a well-developed backshore, mainly due to the lower urban settlement in these areas. Thus, efforts focused on preserving nesting beaches, especially those under high urbanization, are a key factor for sea turtle preservation.

High accuracy tracking reveals how small conservation areas can protect marine megafauna.

Space use estimates can inform conservation management but relaying high-accuracy locations is often not straightforward. We used Fastloc-GPS Argos satellite tags with the innovation of additional data relay via a ground station (termed a "Mote") to record high volumes (typically >20 locations per individual per day) of high accuracy tracking data. Tags were attached in the Chagos Archipelago (Indian Ocean) in 2018-2019 to 23 immature turtles of two species for which there have been long-standing conservation concerns: 21 hawksbill turtles (Eretmochelys imbricata) and two green turtles (Chelonia mydas). Over long tracking durations (mean 227.6d per individual), most turtles moved very little. For example, 17 of 21 hawksbill turtles remained continuously in the lagoon where they were equipped, with 95% and 50% utilization distributions (UDs) averaging only 1.03 and 0.18km2 , respectively. Many individuals, and both species, could use the same small spaces, i.e., individuals did not maintain unique home ranges. However, three hawksbill turtles travelled hundreds of kilometers from the tagging site. Our results show that, for some large marine vertebrates, even small protected areas of only a few square kilometers can encompass the movements of a large proportion of individuals over long periods. High accuracy tracking may likewise reveal the details of space use for many other animals that move little and/or use important focal areas and where previous low-accuracy tracking techniques have tended to overestimate space use.

Penetasan telur penyu sisik (Eretmochelys imbricata) dengan kedalaman yang berbeda

This research was conducted from November 2018 until January 2019 which was held at the UPTD Conservation and Supervision of Marine Resources and Fisheries in West Sumatera, Pariaman City. The aim of the research is to know hatchling hawksbill sea turtle eggs based on nest depth. The method used in this study is a nonfactorial randomized block design (RBD) consisting of 3 treatments and 3 replications. The treatments used were treatment A (with a depth of 30 cm incubation nest), treatment B (with a depth of incubation nest 40 cm), and Treatment C (with a depth of incubation nest 50 cm). The results of this study showed that hatching hawksbill eggs hatched very significantly, the best hatching percentage was in treatment A (30cm) with 78% hatching at 6:00 a.m. with hatching temperature range of 24-28oC, hatching pH of 6,6-6,8 and medium sized incubation sand with a size of 0.150 mm with a weight reaching 461 grams.Keywords: Hatching percentage, Hawksbill turtle, pH, Temperature

Low Diversity and Strong Genetic Structure Between Feeding and Nesting Areas in Brazil for the Critically Endangered Hawksbill Sea Turtle

Marine turtle nesting areas are characterized by receiving several females every year. The species Eretmochelys imbricata, known as hawksbill turtle is listed as Critically Endangered by the IUCN, and has been the target of studies on genetic structure and population diversity in nesting areas. Therefore, this study aimed to analyze the genetic diversity and haplotype composition of populations sampled in nesting areas from the coast of northeastern Brazil based on the mtDNA D-loop region. We used genetic information and compared it with data from feeding areas available in public databases. We recorded a total of six exclusive haplotypes in the nesting areas and 27 exclusive haplotypes for the feeding areas. The H_1 haplotype was shared in all nesting areas. The turtles of these regions had a low diversity and a genetic structure composed of five divergent groups separating the reproductive areas from the ones of feeding areas. Positive and significant geographical distance relationships were also recorded with FST values (r = 0.2302, p = 0.007). Our results revealed that hawksbill turtles from reproductive areas comprise a single population that needs management strategies to protect the threatened species, in addition to providing information that contributes to future actions for the species conservation.

Distribution and temporal trends in the abundance of nesting sea turtles in the Red Sea

Mobile species often aggregate at predictable places and times to ensure that individuals find mates and breed in suitable habitats. Sea turtles demonstrate this life history trait, which can make these species highly susceptible to population declines if nesting habitats are lost or degraded. Conservation management thus requires knowledge of where and when turtles nest and changes in abundance in these habitats through time. Here, we compiled new and published data and used a novel analysis to describe seasonality, annual abundance and spatial distribution of nesting green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) turtles in data-deficient populations that inhabit the Red Sea. Major new rookeries were identified for green turtles at Jazirat11‘Jazirat’ is the Arabic word for ‘island of’. Mashabah (113 and 179 nesting females in 2018 and 2019) and for hawksbill turtles at Jazirat Al Waqqadi (79 nesting females in 2018), both of which are located on nearshore islands of the Kingdom of Saudi Arabia in an area subject to industrial, residential and ecotourism developments. An upward trend in annual abundance of nesting sea turtles was estimated at some sites including Ras Al Baridi (Saudi Arabia), a major rookery of green turtles in the Red Sea, where the annual numbers increased from 14–110 individuals in 1982–1995 to 178 and 330 individuals in 2018 and 2019. This integrative work provides the most up-to-date, comprehensive information on nesting sea turtles in the Red Sea and documents a critical baseline for sea turtle conservation and future management effort.

Plastic Pollution and Small Juvenile Marine Turtles: A Potential Evolutionary Trap

The ingestion of plastic by marine turtles is now reported for all species. Small juvenile turtles (including post-hatchling and oceanic juveniles) are thought to be most at risk, due to feeding preferences and overlap with areas of high plastic abundance. Their remote and dispersed life stage, however, results in limited access and assessments. Here, stranded and bycaught specimens from Queensland Australia, Pacific Ocean (PO; n = 65; 1993–2019) and Western Australia, Indian Ocean (IO; n = 56; 2015–2019) provide a unique opportunity to assess the extent of plastic (> 1mm) ingestion in five species [green (Chelonia mydas), loggerhead (Caretta caretta), hawksbill (Eretmochelys imbricata), olive ridley (Lepidochelys olivacea), and flatback turtles (Natator depressus)]. In the Pacific Ocean, high incidence of ingestion occurred in green (83%; n = 36), loggerhead (86%; n = 7), flatback (80%; n = 10) and olive ridley turtles (29%; n = 7). There was an overall lower incidence in IO; highest being in the flatback (28%; n = 18), the loggerhead (21%; n = 14) and green (9%; n = 22). No macroplastic debris ingestion was documented for hawksbill turtles in either site although sample sizes were smaller for this species (PO n = 5; IO n = 2). In the Pacific Ocean, the majority of ingested debris was made up of hard fragments (mean of all species 52%; species averages 46–97%), whereas for the Indian Ocean these were filamentous plastics (52%; 43–77%). The most abundant colour for both sites across all species was clear (PO: 36%; IO: 39%), followed by white for PO (36%) then green and blue for IO (16%; 16%). The polymers most commonly ingested by turtles in both oceans were polyethylene (PE; PO-58%; IO-39%) and polypropylene (PP; PO-20.2%; IO-23.5%). We frame the high occurrence of ingested plastic present in this marine turtle life stage as a potential evolutionary trap as they undertake their development in what are now some of the most polluted areas of the global oceans.

Lipid profiling suggests species specificity and minimal seasonal variation in Pacific Green and Hawksbill Turtle plasma.

In this study, we applied multiple reaction monitoring (MRM)-profiling to explore the relative ion intensity of lipid classes in plasma samples from sea turtles in order to profile lipids relevant to sea turtle physiology and investigate how dynamic ocean environments affect these profiles. We collected plasma samples from foraging green (Chelonia mydas, n = 28) and hawksbill (Eretmochelys imbricata, n = 16) turtles live captured in North Pacific Costa Rica in 2017. From these samples, we identified 623 MRMs belonging to 10 lipid classes (sphingomyelin, phosphatidylcholine, free fatty acid, cholesteryl ester, phosphatidylserine, phosphatidylinositol, phosphatidylglycerol, phosphatidylethanolamine, ceramide, and triacylglyceride) and one metabolite group (acyl-carnitine) present in sea turtle plasma. The relative ion intensities of most lipids (80%) were consistent between species, across seasons, and were not correlated to body size or estimated sex. Of the differences we observed, the most pronounced was the differences in relative ion intensity between species. We identified 123 lipids that had species-specific relative ion intensities. While some of this variability is likely due to green and hawksbill turtles consuming different food items, we found indications of a phylogenetic component as well. Of these, we identified 47 lipids that varied by season, most belonging to the structural phospholipid classes. Overall, more lipids (n = 39) had higher relative ion intensity in the upwelling (colder) season compared to the non-upwelling season (n = 8). Further, we found more variability in hawksbill turtles than green turtles. Here, we provide the framework in which to apply future lipid profiling in the assessment of health, physiology, and behavior in endangered sea turtles.

Satellite tracking improves conservation outcomes for nesting hawksbill turtles in Solomon Islands

The remote tracking of endangered animals is often justified by the application of movement data to conservation problems, but examples of where scientific findings have rapidly informed conservation actions are relatively rare. In this study we satellite tracked 30 adult female hawksbill turtles (Eretmochelys imbricata) that were captured after nesting in the Arnavon Community Marine Park (ACMP), Solomon Islands. Ten hawksbill turtles were tagged in April 2016, ten in May 2017 and ten in November 2018. Our primary aim was to determine if the ACMP boundaries that were demarcated in 1995 were large enough to protect female hawksbill turtles throughout their entire nesting season. Our home range analysis revealed that collectively, tracked hawksbill turtles spent 98.5% of their inter-nesting season within the ACMP, confirming that the original park boundaries were adequate. Our first year's results were shared with community and government stakeholders and assisted in getting the ACMP declared as the Solomon Islands first national park in May 2017. Our fine scale analysis of inter-nesting habitats also highlighted that most hawksbill turtle nests were being laid on an island in the ACMP that did not have a permanent ranger presence and was experiencing persistent poaching. Based on this finding an additional ranger station was established on this uninhabited island and staffed with community rangers in 2017. Our study demonstrates how involving community, government and NGO stakeholders in applied research can lead to results being rapidly utilised to inform policy and conservation practice as soon as they become available.

Movements and distribution of hawksbill turtles in the Eastern Indian Ocean

Western Australia (WA) is one of the largest remaining hotspots for hawksbill turtles. Providing data from this region is a total of 42 satellite transmitter deployments on nesting hawksbill turtles at six rookeries (five located in WA and one in Timor-Leste) between 2000 and 2017. We used this data to quantify inter-nesting, migratory and foraging habitat use and overlap with protected areas. Turtles from WA rookeries (n = 40) remained in WA waters during their inter-nesting, migration and foraging phases, whereas those from Timor-Leste (n = 2) migrated to and foraged in WA. While inter-nesting, turtles remained in relatively small areas with an average 50% occupancy core of 39 ± 28 km2. Apart from one rookery, most of their inter-nesting distribution was contained within existing protected areas. Turtles migrating from WA rookeries remained in shallow continental-shelf waters (< 200 m), mainly following the coastline while dispersing in a north-easterly direction, whereas turtles from Timor-Leste crossed international waters. We calculated high overlap of individual turtles (56%) in a migratory corridor along the Pilbara coast, an area previously identified as critical for other migratory megafauna species. Turtles used at least 13 distinct foraging grounds, extending over ~900 km and in waters ranging from 1.5 to 84 m deep. Only 33% of this area was encompassed by either designated Biologically Important Areas for foraging hawksbill turtles (10%), or Australian and State-protected areas (23%). Unusually for this species, 17% of the turtles foraged in relatively deep waters (> 20 m), revealing new foraging habitats in need of further research and management. Our study provides the first quantitative stock-wide distribution maps for WA adult female hawksbill turtles during the different phases of their life cycle. These distributions can be used to directly refine critical areas for this species, particularly for foraging as currently only around a third of the foraging distribution we calculated overlapped with designated protected areas. It appears that Australia-focussed management strategies are appropriate for adult female hawksbill turtles from WA rookeries as they do not leave Australian waters. However, for Timor-Leste adult females, evidence of international migrations, unknown stock affiliation and limited samples sizes show that further investigation is required to understand how domestic and regional management is structured to ensure their future conservation.

Effectiveness and design of marine protected areas for migratory species of conservation concern: A case study of post-nesting hawksbill turtles in Brazil

Marine protected areas (MPAs) are among the most widely used strategy to protect marine ecosystems and are typically designed to protect specific habitats rather than a single and/or multiple species. To inform the conservation of species of conservation concern there is the need to assess whether existing and proposed MPA designs provide protection to these species. For this, information on species spatial distribution and exposure to threats is necessary. However, this information if often lacking, particularly for mobile migratory species, such as marine turtles. To highlight the importance of this information when designing MPAs and for assessments of their effectiveness, we identified high use areas of post-nesting hawksbill turtles (Eretmochelys imbricata) in Brazil as a case study and assessed the effectiveness of Brazilian MPAs to protect important habitat for this group based on exposure to threats. Most (88%) of high use areas were found to be exposed to threats (78% to artisanal fishery and 76.7% to marine traffic), where 88.1% were not protected by MPAs, for which 86% are exposed to threats. This mismatch is driven by a lack of explicit conservation goals and targets for turtles in MPA management plans, limited spatial information on species' distribution and threats, and a mismatch in the scale of conservation initiatives. To inform future assessments and design of MPAs for species of conservation concern we suggest that managers: clearly state and make their goals and targets tangible, consider ecological scales instead of political boundaries, and use adaptative management as new information become available.

Habitat selection and 3D space use partitioning of resident juvenile hawksbill sea turtles in a small Caribbean bay

Understanding how aquatic animals select and partition resources provides relevant information about community dynamics that can be used to help manage conservation efforts. The critically endangered hawksbill sea turtle (Eretmochelys imbricata) spends an extended part of its juvenile development in coastal waters. A strong proclivity to remain resident in small areas, often in high density, raises questions about how juveniles partition resources including selection of habitat and spatial overlap among conspecifics. Using between 36 and 41 acoustic receivers in the 1.5 km2 study site, this study quantified day-and-night habitat selection, as well as 2D and 3D space use of 23 juvenile hawksbills within two adjacent Caribbean foraging grounds—Brewers Bay and Hawksbill Cove, St. Thomas, US Virgin Islands—between 2015 and 2018. We found that coral reef, rock, and the artificial dolosse forming an airport runway, were the most strongly selected habitats based on resource selection indices. Individual activity spaces in 2D and 3D were both larger during the day compared to night, although the same parts of the bay were used by each individual during both periods. The 3D approach also showed deeper space use during the day. Weekly comparisons of activity space between individuals showed limited overlap (mean 95% UD overlap; day: 0.15 (2D) and 0.07 (3D), night: 0.11 (2D) and 0.03 (3D)), suggesting some degree of resource partitioning or territoriality. Results from this study provide relevant space use information for resource management of juvenile hawksbills, in which many populations are facing habitat degradation and population declines.

KAJIAN PENGELOLAAN PESISIR DAN LAUT DENGAN SISTEM ZONASI DI KAWASAN KONSERVASI PERAIRAN DAERAH KECAMATAN LIUKANG TUPPABIRING

Liukang Tuppabiring is a waters with marine biodiversity potential large enough to be developed and managed sustainably. Utilization around the coral reefs in the waters of the Liukang Tuppabiring sub-district currently tends to lead to destructive use, so it is necessary to take damage prevention measures immediately. The results showed the condition of coral cover in the medium and damaged, while at stations 1,2,3,4,6 (25,47-41.07%), while conditions were good at station 5 (56.20%). The number of individual reef fish is 290 individuals from 46 species of 22 genera 11 families. At the research location also identified one type of protected biota namely Hawksbill (Eretmochelys imbricata). Coral damage that occurred at 6 observation stations was more caused by the practice of using destructive and environmentally unfriendly fishing equipment such as bombs, trawls, and the use of poisons. The priority strategies undertaken in the management of coral reefs at the study site are 1) Management of environmentally friendly coral reefs where the community as a manager with strong support from the Government; 2) Making clear rules related to utilization in coral reef areas and establishing a POSMAKWAS institution to avoid more severe coral damage; 3) Improve supervision and law enforcement must be firm in relation to the use of fishing gear that can damage coral reef ecosystems.

A non-invasive system to measure heart rate in hard-shelled sea turtles: potential for field applications.

To measure the heart rate of unrestrained sea turtles, it has been believed that a probe must be inserted inside the body owing to the presence of the shell. However, inserting the probe is invasive and difficult to apply to animals in the field. Here, we have developed a non-invasive heart rate measurement method for some species of sea turtles. In our approach, an electrocardiogram (ECG) was performed using an animal-borne ECG recorder and two electrodes-which were electrically insulated from seawater-pasted on the carapace. Based on the measured ECG, the heartbeat signals were identified with an algorithm using a band-pass filter. We implemented this algorithm in a user-friendly program package, ECGtoHR. In experiments conducted in a water tank and in a lagoon, we successfully measured the heart rate of loggerhead, olive ridley and black turtles, but not green and hawksbill turtles. The average heart rate of turtles when resting underwater was 6.2 ± 1.9 beats min-1 and that when moving at the surface was 14.0 ± 2.4 beats min-1. Our approach is particularly suitable for endangered species such as sea turtles, and has the potential to be extended to a variety of other free-ranging species. This article is part of the theme issue 'Measuring physiology in free-living animals (Part I)'.

Measuring of the effects of a sea turtle conservation education program on children's knowledge and attitudes in Grenada, West Indies

Grenada, a multi-island country in the Caribbean Sea, supports aggregates of critically endangered hawksbill turtles (Eretmochelys imbricata), endangered green turtles (Chelonia mydas) and vulnerable leatherback turtles (Dermochelys coriacea). These species play an integral role within the marine ecosystem and are important to ecotourism in Grenada. They are also negatively impacted by anthropogenic factors in Grenada such as legal and illegal hunting, habitat loss, pollution, and by-catch. Conservation educational programs represent a powerful approach for increasing public knowledge about sea turtles and engaging stakeholders to improve management of sea turtle populations. However, little data is available that quantifies the impact that these programs have on participants. A 10 day, active-learning sea turtle education program was developed for 22, nine to twelve-year old children who were selected for participation by their school principles, on the island of Carriacou, a dependency of Grenada. Knowledge and attitude changes towards sea turtle biology and conservation were quantified with pre- and post-curriculum test scores consisting of multiple-choice basic biology questions (n = 15) and Likert-scale questions (n = 16) that assessed the variables understanding and concern, locus of control, and level of verbal commitment. Student's knowledge of sea turtle biology significantly increased 12.3 percentage points, including a 16.3 percentage point increase for females (n = 11) and 7.9 for males (n = 11). Likert-scale scores demonstrated that students held and maintained a positive attitude towards sea turtle conservation. Score changes were not significant but females trended towards a more positive attitude change for each variable post-curriculum while males trended towards less positive attitudes. Possible influences driving these gender differences are discussed. Public education remains central to engaging communities in sea turtle conservation and ocean resource management efforts in the Caribbean region. Understanding the effects of conservation education programs on participant knowledge and attitudes is central to our ability to progress the curriculum and better engage communities in conservation efforts.

Chelonid Alphaherpesvirus 5 Prevalence and First Confirmed Case of Sea Turtle Fibropapillomatosis in Grenada, West Indies.

Simple SummaryFibropapillomatosis is a disease of sea turtles that is likely caused by the virus chelonid alphaherpesvirus-5. Sea turtles, and especially green sea turtles, can develop extensive tumors that impede foraging and swimming and can result in high morbidity and mortality. The presence of the virus has not been assessed in Grenada and fibropapillomatosis has anecdotally not been observed in the island’s sea turtle aggregates. From 2017 to 2019, a total of 167 green, leatherback, and hawksbill turtles were examined for fibropapilllomatosis. Skin and blood samples were examined for the presence of the virus and previous exposure to the virus was assessed by checking for antibodies in the blood. No signs of fibropapillomatosis or active viral infection were found in any turtle examined during the study. Antibody testing showed that 34.6% of green turtles examined had been previously exposed to the virus. In 2020, the first case of fibropapillomatosis occurred in a green turtle in Grenada and the presence of the virus was confirmed in tumor samples. These results indicate that to date, active viral infection is rare in Grenada’s turtles, although viral exposure in green sea turtles is relatively high. The impact of fibropapillomatosis in Grenada is suggested to be low at the present time, and further studies examining factors that may influence disease are warranted.Chelonid alphaherpesvirus 5 (ChHV5) is strongly associated with fibropapillomatosis, a neoplastic disease of sea turtles that can result in debilitation and mortality. The objectives of this study were to examine green (Chelonia mydas), hawksbill (Eretmochelys imbricata), and leatherback (Dermochelys coriacea) sea turtles in Grenada, West Indies, for fibropapillomatosis and to utilize ChHV5-specific PCR, degenerate herpesvirus PCR, and serology to non-invasively evaluate the prevalence of ChHV5 infection and exposure. One-hundred and sixty-seven turtles examined from 2017 to 2019 demonstrated no external fibropapilloma-like lesions and no amplification of ChHV5 DNA from whole blood or skin biopsies. An ELISA performed on serum detected ChHV5-specific IgY in 18/52 (34.6%) of green turtles tested. In 2020, an adult, female green turtle presented for necropsy from the inshore waters of Grenada with severe emaciation and cutaneous fibropapillomas. Multiple tumors tested positive for ChHV5 by qPCR, providing the first confirmed case of ChHV5-associated fibropapillomatosis in Grenada. These results indicate that active ChHV5 infection is rare, although viral exposure in green sea turtles is relatively high. The impact of fibropapillomatosis in Grenada is suggested to be low at the present time and further studies comparing host genetics and immunologic factors, as well as examination into extrinsic factors that may influence disease, are warranted.

Species and population specific gene expression in blood transcriptomes of marine turtles

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.

Why do Argos satellite tags stop relaying data?

Satellite tracking of animals is very widespread across a range of marine, freshwater, and terrestrial taxa. Despite the high cost of tags and the advantages of long deployments, the reasons why tracking data from tags stop being received are rarely considered, but possibilities include shedding of the tag, damage to the tag (e.g., the aerial), biofouling, battery exhaustion, or animal mortality.We show how information relayed via satellite tags can be used to assess why tracking data stop being received. As a case study to illustrate general approaches that are broadly applicable across taxa, we examined data from Fastloc‐GPS Argos tags deployed between 2012 and 2019 on 78 sea turtles of two species, the green turtle (Chelonia mydas) and the hawksbill turtle (Eretmochelys imbricata).Tags transmitted for a mean of 267 days (SD = 113 days, range: 26–687 days, median = 251 days). In 68 of 78 (87%) cases, battery failure was implicated as the reason why tracking data stopped being received. Some biofouling of the saltwater switches, which synchronize transmissions with surfacing, was evident in a few tags but never appeared to be the reason that data reception ceased.Objectively assessing why tags fail will direct improvements to tag design, setup, and deployment regardless of the study taxa. Assessing why satellite tags stop transmitting will also inform on the fate of tagged animals, for example, whether they are alive or dead at the end of the study, which may allow improved estimates of survival rates.

KAJIAN KONDISI LINGKUNGAN TEMPAT PENELURAN PENYU DI DESA PASIE LEMBANG, ACEH SELATAN

Indonesian marine waters have habitats for six species of sea turtles from seven species in the world, namely green turtles (green turtles, Chelonia mydas), olive ridley turtles (olive ridley, Lepidochelys olivacea), loggerhead turtles (loggerhead, Caretta caretta), hawksbill turtles (hawksbill, Eretmochelys imbricata), leatherback turtles (leatherback, Dermochely coriacea) and flatback turtles (flatback, Natator depressus). All types of turtles in Indonesia are protected under PP. 7 of 1999 concerning Preservation of Plant and Animal Species and PP No. 8 of 1999 concerning the Utilization of Wild Plant and Animal Species, which means that all trade in a state of life or death is prohibited. This is because almost all turtle species in Indonesia have experienced a decline in population so they are categorized as endangered

Optimal Feeding Frequency for Captive Hawksbill Sea Turtle (Eretmochelys imbricata)

Simple SummaryHead-starting programs of hatchlings before release of yearlings to natural habitat are an alternative approach for restoring the population of critically endangered sea turtles. Hawksbill sea turtle has been reared in captivity programs in several countries, while the feeding regimens have never been optimized. In the current study, the feeding frequency of hawksbill sea turtle was optimized in indoor experimental conditions. Two-month-old turtles were fed at different frequencies: one meal daily at 12.00 h, two meals daily at 08.00 and 12.00 h, two meals daily at 08.00 and 16.00 h, two meals daily at 12.00 and 16.00 h or three meals daily at 08.00, 12.00, and 16.00 h. At the end of an 8-week trial, two meals daily with long time interval (at 08.00 and 16.00 h) were optimal, based on assessment criteria of growth, feed utilization, digestive enzyme markers, available and unavailable nutrients present in the feces, hematological parameters, and carapace elemental composition. This finding could be directly used as a feeding guideline supporting the head-starting programs of this species.Hawksbill sea turtle (Eretmochelys imbricata) has been reared in head-starting captivity programs, while the feeding regimens have never been optimized. In the current study, the feeding frequency of hawksbill sea turtle was investigated in indoor experimental conditions. Two-month-old turtles (38.98 ± 0.02 g) were distributed to triplicates of five treatments containing three turtles each and they were fed at different frequencies: one meal daily at 12.00 h (1M12), two meals daily at 08.00 and 12.00 h (2M8–12), two meals daily at 08.00 and 16.00 h (2M8–16), two meals daily at 12.00 and 16.00 h (2M12–16), or three meals daily at 08.00, 12.00 and 16.00 h (3M8–12–16). At the end of an 8-week trial, growth performance (specific growth rate 2.39 ± 0.02% body weight day−1) and feed consumption (feeding rate 2.00 ± 0.43 g day−1) were highest for turtles fed 2M8–16, followed by 2M12–16 or 3M8–12–16 relative to the other treatments (p ˂ 0.05). These treatments had significantly higher trypsin specific activity and trypsin/chymotrypsin ratio, and vice versa for lipase specific activity and amylase/trypsin ratio, relative to the remaining treatments. These match well with the fecal thermal properties that indicate amounts of available and unavailable nutrients present in the feces. Hematological parameters and carapace elemental composition showed no negative effects to turtles in 2M8–16 treatment. Therefore, two meals daily with long time interval were optimal for feeding hawksbill sea turtle. Findings from the current study could be directly used as a feeding guideline supporting the head-starting programs of this species.