Lepidochelys Research Articles

Conservation and management of olive ridley sea turtles and their nesting habitat: A study at Rushikulya rookery, Odisha, east coast of India

Odisha coast, along the east coast of India, has the world's largest mass nesting sites (rookeries) for olive ridley (Lepidochelys olivacea) sea turtles. It has three rookeries namely Gahirmatha, Devi and Rushikulya. Olive ridley sea turtles and their habitat along the Odisha coast often face natural and anthropogenic threats leading to failure of mass nesting (arribada) and a population decline. The focus of the present study is to understand the coastal processes near the Rushikulya rookery, assess the impacts of natural and anthropogenic threats to the nesting population and their habitat, and suggest a management plan for the conservation of sea turtles and their habitat. Coastal processes and the associated geomorphological changes, shoreline change, and cyclonic disturbances at the Rushikulya rookery from 2008 to 2019 were studied. It is revealed that the natural threats for arribada are cyclonic storms, high wave exposure, and sand spit growth leading to erosion of the nesting habitat and debris accumulation. Coastal processes, such as east-southeast to south-southeast waves with moderate wave height, lunar semidiurnal tide, moderate southwest current, and predominantly southerly and easterly winds with moderate speed, are identified as favourable conditions for the sea turtles prior to and during an arribada. The study reveals that nesting on the sand spit is vulnerable because of frequent wave exposure and washout, while the beach to the north of the estuary is the most preferred and safe habitat for arribada. Coastal development, incidental capture, entanglement in gill nets, fisheries bycatch and illegal take are revealed as the major anthropogenic threats. Based on natural and anthropogenic threats, the local knowledge of the fishermen and the status of legislation, the study suggests an integrated regional management plan for the conservation of olive ridley sea turtles and their nesting habitat.

The first occurrence of Kemp’s Ridley turtle (Lepidochelys kempii) in Raja Ampat, Indonesia

Abstract. Widaysari F, Nugroho A, Arafat G, Sunoko R, Wahyudin RA, Sayuti M, Bakkula E, Ballamu F. 2023. The first occurrence of Kemp’s Ridley turtle (Lepidochelys kempii) in Raja Ampat, Indonesia. Biodiversitas 24: 4934-4942. Territory Indonesian waters are one of the waters in Southeast Asia that have been a turtle habitat; six of the seven types of turtles live in these waters, and Kemp ridley's turtle (Lepidochelys kempii) is the seventh reported to have recently emerged. The research objectives of the study were to identify the area location emergence of Kemp’s Ridley turtle, determine morphology, and release Kemp’s Ridley turtle. Location identification was based on the Raja Ampat District Central Statistics Agency data. Visual identification of turtles proceeds by looking at their morphology, namely carapace shape, number of vertebral and costal scutes, the form of the plastron, number of inframarginal scutes, and appearance of head shape juxtaposed on External Morphology. The water area where Kemp’s Ridley turtle was found had a constant temperature, moderate wind speed, high humidity, and rainfall. The results of identifying the turtle morphology matched Kemp’s Ridley turtle. After outreach to the community, Kemp’s Ridley turtles were released into nature. The first appearance of the Kemp’s Ridley turtle in Indonesia is undoubtedly an exciting study material for further study regarding the migration map, distribution, and other factors that cause changes in its migration.

Olive Ridley Sea Turtle Incubation in Natural Conditions Is Possible on Guatemalan Beaches

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

Feeding ecology of the olive ridley turtle (Lepidochelys olivacea) in southern Brazil

Feeding ecology of the olive ridley turtle (Lepidochelys olivacea) in southern Brazil

Climate-mediated population dynamics for the world’s most endangered sea turtle species

Restricted range, and subsequently small population size, render Kemp’s ridley sea turtles (Lepidochelys kempii) the most globally endangered sea turtle species. For at least two decades preceding conservation, high egg harvest rates reduced annual cohort recruitment. Despite > 50 years of dedicated conservation, annual nest counts remain well below a landmark 1947 level. Prior studies attribute less robust than anticipated nest count rebound to multiple contemporary concerns; however, analyses herein convey optimistic interpretation. In objective 1, improved analysis of the ratio of hatchlings to nests since 1966 suggested age structure stabilization as a more likely basis for nest count trends after 2005 than density-dependent effects. In objective 2, multiple regression revealed a lagged (≤ 13 years prior) climate influence on nests (adj. r2 = 0.82) and hatchlings per nest (adj. r2 = 0.94) during 2006–2022. In objectives 3 and 4, a simulator modeled population response to changes in a suite of demographic rates including survival. Across 32 models, high survival and dynamic cohort sex ratio, sexual maturity age, and the ratio of clutch frequency to remigration interval best explained nesting trends during 1966–2022. These novel findings provide alternative perspective for evaluating species recovery criteria and in turn refine future nest trend expectations.

FIRST OSTEOMYELITIS RECORDS IN NESTING FEMALE TURTLES OF Lepidochelys olivacea (ESCHOLTZ 1829) AT LA ESCOBILLA SANCTUARY, OAXACA, MEXICO

We provide the first records of osteomyelitis in shell of nesting female turtles of Lepidochelys olivacea at La Escobilla Sanctuary, Mexico. Osteomyelitis is an infectious and inflammatory disease of the bone, characterized by necrosis and destruction of bone tissue. Until now, there no exist records of this infectious disease of bone in olive ridley turtle (Lepidochelys olivacea) in tropical waters.

Conservation‐relevant reproductive parameters from long‐term tagging of two globally important sea turtle nesting aggregations in Central Africa

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

Evaluation of sea turtle morbidity and mortality within the Indian Ocean from 12 years of data shows high prevalence of ghost net entanglement.

Anthropogenic activities can negatively affect sea turtle populations. Quantifying the effect of human actions on these threatened species can help guide management strategies to reduce adverse impacts. However, such assessments require extensive effort and resources and as such have not been carried out in many areas of important sea turtle habitat, including the Republic of the Maldives (Maldives). Here, we utilise 12 years of data (2010-2022) collected from marine turtle stranding and rehabilitation cases from across the Maldives to identify the key threats in this region. Olive ridley turtles were found stranded or injured most frequently (74.7% of total cases), along with hawksbill (15.2%), and green (10.1%) turtles. Anthropogenic factors were the primary cause of injury or stranding in 75.2% of cases with entanglement in ghost fishing gear being the most common (66.2% of all cases). Other causes of morbidity, such as from turtles being kept as pets (5.6%), boat strikes (<1%), bycatch (<1%), and poaching (<1%) were recorded less frequently. Olive ridley turtles were more likely to have injuries associated with entanglement than other species and showed a peak in admissions during the northeast monsoon, in the period following the known arribada nesting season in nearby India. Turtles admitted to rehabilitation following entanglement were released a mean of 70 days sooner and had 27.5% lower mortality rates than for other causes of admission. This study highlights the high prevalence of ghost net entanglement of sea turtles within the Maldives. The topic of ghost fishing is of global importance and international cooperation is critical in tackling this growing issue.

Empowering the Rural Community as Turtle Breeder: Case Studi of Dunu Village, Gorontalo Utara Regency

Turtles are marine reptiles that have existed on Earth for millions of years and have managed to survive until today. Turtles play a crucial role in the marine ecosystem, maintaining the balance of nature and contributing to marine biodiversity. The method used in this research is a qualitative approach, which includes conducting in-depth interviews, participatory observations, and analyzing relevant documents. The data obtained will be analyzed using descriptive and interpretative approaches to illustrate the process of empowering the rural community in Dunu Village. This research aims to understand how the empowerment of the Dunu village community as turtle breeders takes place. The study was conducted for a duration of two weeks, starting from June 27, 2023, to July 11, 2023. The research findings indicate that in Dunu village, Gorontalo Utara Regency, three types of turtles are being conserved. The turtle species involved are the green turtle (Chelonia mydas), hawksbill turtle (Eretmochelys imbricata), and olive ridley turtle (Lepidochelys olivacea). There are two individuals from Dunu village who are recognized as professional turtle breeders and actively participate in the protection of turtle eggs, caring for hatchlings, and conducting patrols along the beach where the turtles nest. These two breeders received training from the Balai Konservasi Sumber Daya Alam (BKSDA) Sulawesi Utara through the Seksi Konservasi Wilayah II Gorontalo.

The use of the territorial sea by Lepidochelys olivacea (Eschscholtz, 1829) in front of nesting beaches in Oaxaca, Mexico

Scientific research focused on sea turtle monitoring and management has relied on nesting beaches, but little attention has been paid to surveying turtles in the territorial sea off nesting beaches. This study aimed to evaluate how the Olive Ridley turtle, Lepidochelys olivacea, uses the territorial sea off the nesting beaches in Puerto Escondido, Puerto Ángel, Santa María Huatulco, and Morro Ayuta, in Oaxaca, Mexico. Between December 2017 and August 2018, 2394 individuals were sighted in the territorial sea engaged in the following activities: feeding (6 individuals), mating (164 individuals), swimming (2172 individuals), and resting (49 individuals). We analyzed the diet and body condition of L. olivacea and identified which biophysical factors affect the distribution of these sea turtles in the region. We also recorded direct interactions with fishers and tourism service providers. We captured 40 individuals, collected morphometric data, and analyzed esophageal content to characterize feeding habits, which were correlated with a body condition index. Diet items included crustaceans, tunicates, four commercially important fish species, jellyfish, mollusks, and algae. Approximately 95% of turtles exhibited very good body condition. The largest turtle aggregations were recorded in Morro Ayuta (898 individuals) and Puerto Ángel (808 individuals). In situ sea surface temperature and chlorophyll-a concentrations from satellite images were used to characterize the territorial sea. Sea surface temperature was negatively correlated with turtle abundance. Management and conservation actions are needed for sea turtles that address the negative interactions with fishers (e.g., competition for commercially important fish species) and tourism service providers that occur in the territorial sea off nesting beaches to protect these crucial reproductive habitats in the long term.

New Delhi metallo-β-lactamase-1-producing Citrobacter portucalensis belonging to the novel ST264 causing fatal sepsis in a vulnerable migratory sea turtle

Olive ridley (Lepidochelys olivacea) turtles migrate across tropical regions of the Atlantic, Pacific, and Indian Oceans. Worryingly, olive ridley populations have been declining substantially and is now considered a threatened species. In this regard, habitat degradation, anthropogenic pollution, and infectious diseases have been the most notorious threats for this species. We isolated a metallo-β-lactamase (NDM-1)-producing Citrobacter portucalensis from the blood sample of an infected migratory olive ridley turtle found stranded sick in the coast of Brazil. Genomic analysis of C. portucalensis confirmed a novel sequence type (ST), named ST264, and a wide resistome to broad-spectrum antibiotics. The production of NDM-1 by the strain contributed to treatment failure and death of the animal. Phylogenomic relationship with environmental and human strains from African, European and Asian countries confirmed that critical priority clones of C. portucalensis are spreading beyond hospital settings, representing an emerging ecological threat to marine ecosystems.

Fatal entanglements of sea turtles caused by widely deployed weather instruments

Sea turtles have been found to interact with discarded fishing gear, plastic bags, and balloons, among other anthropogenic materials. One infrequently documented interaction is entanglement in scientific research instruments, which presents a unique management and mitigation challenge. This paper highlights two Kemp's ridley sea turtles that stranded ~10 years apart, deceased and entangled in weather balloons in Virginia, USA. The turtles were recovered 11 and 20 days after the balloons were launched from two different facilities along the Virginia coast in 2009 and 2019, respectively. Based on external evaluation and necropsy findings, both animals were assigned a probable cause of death of debris entanglement. This paper seeks to inform other stranding response organizations, as well as stakeholders like manufacturers and users of weather balloons, of the threats these instruments can pose to marine life. With strengthened education, collaboration, and changes in instrument design, future entanglements may be mitigated.

Reassessment of the olive ridley sea turtle Lepidochelys olivacea nesting population at Nancite Beach, Costa Rica

AbstractNancite is a fully protected beach within the Guanacaste Conservation Area, Costa Rica where olive ridley (Lepidochelys olivacea) sea turtles nest in synchronous mass‐nesting events known as arribadas. Arribadas decreased in magnitude at this beach by approximately 90% during the period 1971–2007 due to unknown causes. The total count estimate of females nesting in a year also decreased over these decades. In the present study, from August 2009 to February 2021, the trend of arribada nesting female abundance and estimated annual production of hatchlings were assessed and compared with previous trend analyses. A total of 62 mass‐nesting events were quantified in the period 2009–2021, with an estimated annual average of 64,694 nesting females. Trend analysis indicated that during our recent study period, the number of females per arribada event increased by an estimated 14% (8%, 20% CI95%). During this period, a mean hatching rate of 33.4% was estimated, corresponding to an overall estimated production average of 2,165,597 per season, which represented an increase of 82.7% compared with a previous estimate for the period 1980–1984, when the arribadas were larger. We suggest that the growth in hatchling production over the past four decades is at least in part responsible for the slight increase in the estimated size of arribadas since 2009/2010. However, because maximal hatching success did not increase above 60%, the beach may be close to reaching carrying capacity, and it seems that high hatchling production may soon level off or begin to decrease. Thus, it is not clear whether current hatchling production will lead to the recovery of the Nancite population to the historical levels documented in the 1970s and early 1980s.

Mitochondrial DNA and local ecological knowledge reveal two lineages of leatherback turtle on the beaches of Oaxaca, Mexico

Despite multiple conservation efforts of the Mexican government, the leatherback turtle is at serious risk of extinction. In this study, we investigated the possible presence of a genetic bottleneck that could prevent the recovery of this species and compared these findings with those of the olive ridley turtle, which is in true recovery. Our results confirmed that a demographic change occurred in the past and the presence of two different leatherback turtle lineages that diverged approximately 13.5 million years ago. Local ecological knowledge (LEK) also described the presence of these two lineages and warned that one is at higher risk of extinction than the other. Genetic analysis confirmed 124 mutations between the two lineages, and much lower genetic diversity in one lineage than the other. Our study highlights and substantiates the power of mixing LEK, environmental history, and genetics to better understand conservation challenges of highly threatened species such as the leatherback turtle. Moreover, we report a new lineage of the leatherback turtle which may represent a distinct species. Future studies should focus on morphological, ecological, biogeographical, evolutionary and conservation perspectives for the analysis of the new lineage.

Developed black beaches - too hot to emerge? Factors affecting sand temperatures at nesting grounds of olive ridley sea turtles (Lepidochelys olivacea)

Climate change research on sea turtles has focused on the impact of rising temperatures on sex ratios, while the thermal ecology of natural nesting grounds has received less attention. Many nesting beaches are highly affected by vegetation loss and urbanization which in turn may affect their thermal profile, particularly at beaches with dark volcanic sand. We studied the sand temperatures on two urban-developed volcanic sea turtle nesting beaches in Guatemala for two years, and their potential effect on the thermal ecology of sea turtle nests by using the olive ridley as model species. We hypothesized that local weather, type of cover at surface, and season (dry vs rainy) will have a pronounced effect on sand temperatures, potentially affecting the hatching success of sea turtles. Average sand temperatures at nesting beaches were almost always above the pivotal temperature (87% of days), and either close to or above the thermal maximum tolerance of sea turtle embryos over longer periods (78% of days). We found that higher air temperatures led to higher sand temperatures, and high relative humidity and precipitation led to lower sand temperatures. As expected, sand temperatures in plots covered by vegetation were lower (32.5 ± 2.8°C) than those without vegetation cover (33.1 ± 2.6°C). Plots close to concrete structures showed the highest sand temperatures (34.0 ± 3.2°C). Our results highlight the relevance of vegetation in buffering the effects of high sand temperatures, which will have profound implications for the resilience of olive ridleys to global warming.

Uncertain future for global sea turtle populations in face of sea level rise

Sea level rise has accelerated during recent decades, exceeding rates recorded during the previous two millennia, and as a result many coastal habitats and species around the globe are being impacted. This situation is expected to worsen due to anthropogenically induced climate change. However, the magnitude and relevance of expected increase in sea level rise (SLR) is uncertain for marine and terrestrial species that are reliant on coastal habitat for foraging, resting or breeding. To address this, we showcase the use of a low-cost approach to assess the impacts of SLR on sea turtles under various Intergovernmental Panel on Climate Change (IPCC) SLR scenarios on different sea turtle nesting rookeries worldwide. The study considers seven sea turtle rookeries with five nesting species, categorized from vulnerable to critically endangered including leatherback turtles (Dermochelys coriacea), loggerhead turtles (Caretta caretta), hawksbill turtles (Eretmochelys imbricata), olive ridley turtles (Lepidochelys olivacea) and green turtles (Chelonia mydas). Our approach combines freely available digital elevation models for continental and remote island beaches across different ocean basins with projections of field data and SLR. Our case study focuses on five of the seven living sea turtle species. Under moderate climate change scenarios, by 2050 it is predicted that at some sea turtle nesting habitats 100% will be flooded, and under an extreme scenario many sea turtle rookeries could vanish. Overall, nesting beaches with low slope and those species nesting at open beaches such as leatherback and loggerheads sea turtles might be the most vulnerable by future SLR scenarios.

Assessment of submergence stress responses and mining allelic variations of submergence tolerance gene Sub1A in Sri Lankan rice germplasm

The Journal of the National Science Foundation of Sri Lanka publishes the results of research in all aspects of Science and Technology. The journal also has a website at http://www.nsf.gov.lk/. 2021 Impact Factor: 0.682The JNSF provides immediate open access to its content on the principle that making research freely available to the public supports a greater global exchange of knowledge.Cover :Leatherback (a), green (b - adult &amp; f - hatchling), hawksbill (c) and olive ridley (d) turtles who nest in Sri Lankan beaches, green turtle crawl marks (e) and by-catch of sea turtles in fisheries (c &amp; d)Photo credits: SJ Perera (a &amp; c), WPN Perera (b &amp; e), K Ekaratne (d &amp; f)

Habitat use of nesting female olive ridley turtles (Lepidochelys olivacea) inferred by stable isotopes in eggs

Olive ridley sea turtles (Lepidochelys olivacea) can use a vast number of different habitats and food sources throughout their life cycle. This species is one such organism that changes both the environment and diet during different life stages. Based on stable isotope analysis (δ13C and δ15N) of the components of fresh eggs (yolk, albumen, and shell) and unhatched eggs (contents and shell), the habitat use of females nesting in the eastern Atlantic Ocean, Brazil, was elucidated. As the yolk is formed months before migration to the nesting areas, it was possible to infer that they originated from both high- and low-latitude feeding areas. For albumen and shell, both carbon and nitrogen isotopic values indicated either the neritic environment at the latitude of the breeding area, tissues of turtles catabolized due to fasting during breeding, or differences in tissue-specific metabolic routing. The contribution of potential prey such as jellyfish for yolk and demersal prey for both albumen and shell demonstrated the plasticity of habitat use of this population and the use of both pelagic and neritic waters. High individual variability further reinforces the need for preservation of the habitats utilized by olive ridley turtles in both neritic and oceanic environments over a vast area of the tropical ocean up within 20 degrees south and north of Equator.

Removal of methylene blue from aqueous solution using raw laterite: an adsorption study

The Journal of the National Science Foundation of Sri Lanka publishes the results of research in all aspects of Science and Technology. The journal also has a website at http://www.nsf.gov.lk/. 2021 Impact Factor: 0.682The JNSF provides immediate open access to its content on the principle that making research freely available to the public supports a greater global exchange of knowledge.Cover :Leatherback (a), green (b - adult &amp; f - hatchling), hawksbill (c) and olive ridley (d) turtles who nest in Sri Lankan beaches, green turtle crawl marks (e) and by-catch of sea turtles in fisheries (c &amp; d)Photo credits: SJ Perera (a &amp; c), WPN Perera (b &amp; e), K Ekaratne (d &amp; f)

Temperature control in an exothermic continuous stirred tank reactor

The Journal of the National Science Foundation of Sri Lanka publishes the results of research in all aspects of Science and Technology. The journal also has a website at http://www.nsf.gov.lk/. 2021 Impact Factor: 0.682The JNSF provides immediate open access to its content on the principle that making research freely available to the public supports a greater global exchange of knowledge.Cover :Leatherback (a), green (b - adult &amp; f - hatchling), hawksbill (c) and olive ridley (d) turtles who nest in Sri Lankan beaches, green turtle crawl marks (e) and by-catch of sea turtles in fisheries (c &amp; d)Photo credits: SJ Perera (a &amp; c), WPN Perera (b &amp; e), K Ekaratne (d &amp; f)