Hawksbill Research Articles

Estimation of soil liquefaction potential in Colombo Port City (Sri Lanka) using several design earthquakes

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 & 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 & d)Photo credits: SJ Perera (a & c), WPN Perera (b & e), K Ekaratne (d & f)

On recurrence relations for moments of dual generalized order statistics for a general transmuted power function distributions with characterizations

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 & 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 & d)Photo credits: SJ Perera (a & c), WPN Perera (b & e), K Ekaratne (d & f)

Effect of oviposition-site deprivation on reproductive performance and life history parameters of dengue vector Aedes aegypti

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 & 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 & d)Photo credits: SJ Perera (a & c), WPN Perera (b & e), K Ekaratne (d & f)

Mechanically exfoliated graphene from Sri Lankan vein graphite for field effect transistor application

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 & 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 & d)Photo credits: SJ Perera (a & c), WPN Perera (b & e), K Ekaratne (d & f)

Insights into the ecological roles of assembling genomes for stimulated methanogenic archaea Methanoculleus in coal seams

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 & 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 & d)Photo credits: SJ Perera (a & c), WPN Perera (b & e), K Ekaratne (d & f)

MARINE TURTLE CONSERVATION PROGRAM AT PUERTO PRINCESA SUBTERRANEAN RIVER NATIONAL PARK: CHALLENGES AND OPPORTUNITIES DURING COVID-19 PANDEMIC

The Puerto Princesa Subterranean River National Park (PPSRNP)-Marine Turtle Conservation Program (MTCP) can be found in West Coast of Palawan Philippines. Geographical location is located in the global center of marine biodiversity, the Coral Triangle. This study described the profile of PPSNRP-MTCP in terms of location, species of marine turtles, number of hatchlings released per year, management organizational structure, conservation activities and, determined the perceived management challenges and opportunities encountered by employees during COVID 19 pandemic. Documentary analysis, net-notgraphy and focal group virtual discussion and structured questionnaires were used in data gathering. There are 3 species that were recorded in the conservation site; Chelonia mydas, Eretmochelys imbricata and Lepidochelys olivacea. Hatchling success from 2015 to 2021 is at an average of 82%, and the mean hatchlings per year is 1659.4 (+/- sd.699.31). Lowest was 697 in 2014-2015, highest in 2019-2020 with 2,476 hatchlings. MTCP is under the supervision of Protected Area Superintendent (PASu). The management activities are; regular monitoring of egg nesting and hatching of the eggs, implementation of easement zone, community coastal clean-up, releasing of hatchlings and conservation awareness campaign. Debris left by typhoon Odette is the perceived very high challenge while the absence of noise during nesting season is perceived at a very high opportunity.

Growth rate and projected age at sexual maturity for immature hawksbill turtles and green turtles foraging in the remote marine protected area of Aldabra Atoll, Seychelles

Changes in marine ecosystems from human stressors, and concerns over how species will respond to these changes have emphasized the importance of understanding and monitoring crucial demographic parameters for population models. Long-lived, migratory, marine vertebrates such as sea turtles are particularly vulnerable to changes. Life-history parameters like growth-in-body size can be largely influenced by environmental processes which can impact population growth. We analyzed a 40-year (1981–2021) capture-mark-recapture dataset from the protected UNESCO World Heritage Site, Aldabra Atoll, Seychelles, to estimate key population parameters, including body growth, for immature green turtles (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata). Curved carapace length (CCL) range was 34.3–110.9 cm (mean ± SD: 51.0 ± 11.4 cm, n = 1191) for green turtles and 28.7–89.4 cm (47.7 ± 14.4 cm, n = 538) for hawksbill turtles. Recapture events, with an 11-month minimum period, revealed a mean annual growth rate of 3.2 ± 1.5 cm year−1 for green turtles (n = 75) and 2.8 ± 1.4 cm year−1 for hawksbill turtles (n = 110). Hawksbill turtles exhibited a non-monotonic growth rate while no significant growth-size relationship was detected for green turtles. Green turtle mean annual growth per 10-cm size class was highest in the larger size classes (50‒69.9 cm). Hawksbill turtle growth rate was highest in the larger size classes (50‒69.9 cm) then declined in the largest size class (70‒79.9 cm). Green turtles and hawksbill turtles may spend > 8 and 18 years, respectively, using Aldabra, Seychelles, as a foraging ground.

HEMATOLOGIC AND BIOCHEMICAL VALUES OF FREE-RANGING HAWKSBILL SEA TURTLES (ERETMOCHELYS IMBRICATA) IN GLOVER'S REEF, BELIZE.

Blood samples were obtained from the dorsal cervical sinus of free-ranging hawksbill sea turtles (Eretmochelys imbricata) collected at Glover's Reef Marine Reserve, 42 km east of the coast of Belize, for hematology and plasma biochemistry analysis. Unknown sex, subadult turtles (N = 32) were sampled in 2013 (n = 22) and 2017 (n = 10). To provide a more robust data set, parameters that did not have statistically significant differences were pooled and treated as a single population. Eleven hematologic parameters were evaluated; of these, five were pooled. Twenty-three plasma biochemical parameters were evaluated; of these, 15 were pooled. The PCV observed in this study (mean 33.44%) was double that observed in two studies of juvenile hawksbills in Dubai (means 17% and 16%), whereas the total WBC count was half that observed in immature and adult hawksbills sampled in the Galápagos (mean 2.91 × 103 versus 5.3 × 103/µl). Total protein and albumin were lower than regionally similar, adult female hawksbills in Brazil (means 3.36 versus 5.45 g/dl and 0.93 versus 2.11 g/dl, respectively). Globulins were higher (mean 2.43 versus 1.06 and 0.5 g/dl), driving the albumin:globulin ratio lower than that observed in two studies of juvenile hawksbills in Dubai (0.4:1 versus 1.1:1 and 1:1, respectively). These findings represent a geographically distinct population from previous reports, highlight the variability in blood parameters from disparate populations, and reaffirm the vital importance of considering a multitude of variables when interpreting reptilian blood values. The similarities in the majority of values observed in 2013 and 2017 provide confidence in the stability of these parameters in this population.

High dive efficiency in shallow water

Dive studies across mammals, birds, reptiles and fish often focus on deep dives, and shallow water diving has tended to be overlooked. For air-breathers, foraging in shallow water poses challenges since the lungs generate buoyancy, and shallow divers must trade off the extent of inhalation against the negative buoyancy needed to avoid floating to the surface. Using high-resolution depth loggers, we addressed this knowledge gap around the ecology of shallow water diving at a foraging site for hawksbill turtles (Eretmochelys imbricata) where depth was typically < 3 m. Contrary to predictions, dive durations were long, particularly at night (mean dive duration per turtle: 17–61 min, n = 12 turtles, n = 2576 nocturnal dives), despite warm water temperatures (24–37 °C). Dive efficiency (% time submerged) for hawksbills was 98%, the highest recorded for any air-breathing marine vertebrate including penguins (60–78%), seals (51–91%), cetaceans (68–87%), and other sea turtle species (68–95%). Hawksbills usually dive for much longer (42–286% increase) than green and loggerhead turtles when depth and temperature are accounted for. Hawksbill turtles likely forage in very shallow water to reduce predation risk from sharks: of 423 hawksbills captured by hand, none had any evidence of shark attack, although large sharks were present in nearby deeper water. Our results challenge the prediction that shallow water dives by air-breathers will usually be short and open the way for comparative studies of the ecology of shallow water diving in a range of other taxa. Our work emphasises the likely importance of predation risk in shaping patterns of habitat utilisation.

Kesesuaian Habitat Peneluran dengan Wisata dan Daya Dukung Kunjungan di Kawasan Pelestarian Penyu Pantai Batu Kumbang, Kabupaten Muko-Muko, Provinsi Bengkulu

The balance of ecological and economic utilization plays a real role in maintaining the stability of turtle nesting habitat on the coast. This study aims to calculate the suitability index and visitation carrying capacity (DDK) of sea turtle nesting habitat to maintain the sustainability of its population. The survey was conducted in December 2020 to January 2021 at Batu Kumbang Beach, Pulau Baru Village, Muko-Muko Regency. The analysis used was the Habitat Suitability Index (IKH), Tourism Conformity Index (IKW), and visitation carrying capacity (DDK). The Mukomuko Turtle Conservation Nature Lovers Community (KPAKPM) reported that this beach is still predominantly used as a nesting habitat for green turtles (Chelonia mydas), olive ridley sea turtles (Lepidochelys olivacea), hawksbill turtles (Eretmochelys imbricata), and leatherback turtles (Dermochelys coriacea) in 2018. At least 35 heads of various types landed and laid eggs here and further decreased in 2020 with only 17 heads. The IKH showed that about 84.06%, 75.36%, and 75.36% belonged to the highly appropriate category and were spread out at Stations 1, 2, and 3, respectively. The suitability of the coastal area is at a value of 2.0 ≤ IKW &lt; 2.5, and is categorized as sustainable. The number of visitors allowed according to DDK is only 84 people per day. Batu Kumbang Beach needs to be managed in a balanced manner with a conservation approach and beach ecotourism to ensure the sustainability and sustainability of nesting habitats for various types of turtles.&#x0D; &#x0D; Keywords: beach conservation, ecosystem, turtle nesting habitat

Characterization of 25 new microsatellite markers for the green turtle (Chelonia mydas) and cross-species amplification in other marine turtle species

The green sea turtle, Chelonia mydas, is a migratory species with a strong natal homing behavior leading to a complex population structure worldwide. The species has suffered severe declines in local populations; it is therefore crucial to understand its population dynamics and genetic structure to adopt appropriate management policies. Here, we describe the development of 25 new microsatellite markers specific to C. mydas and suitable for these analyses. They were tested on 107 specimens from French Polynesia. An average allelic diversity of 8 alleles per locus was reported and observed heterozygosity ranged from 0.187 to 0.860. Ten loci were significantly deviant from the Hardy-Weinberg equilibrium, and 16 loci showed a moderate to high level of linkage disequilibrium (4-22%). The overall Fis was positive (0.034, p-value < 0.001), and sibship analysis revealed 12 half- or full-sibling dyads, suggesting possible inbreeding in this population. Cross-amplification tests were performed on two other marine turtle species, Caretta caretta and Eretmochelys imbricata. All loci successfully amplified on these two species, though 1 to 5 loci were monomorphic. These new markers will not only be relevant for further analyses on the population structure of the green turtle and the two other species, but they will also be invaluable for parentage studies, for which a high number of polymorphic loci are necessary. This can provide important insight into male reproductive behavior and migration, an aspect of sea turtle biology that is of critical importance for the conservation of the species.

Synergistic use of UAV surveys, satellite tracking data, and mark‐recapture to estimate abundance of elusive species

AbstractEstimating population abundance is central to many ecological studies and important in conservation planning. Yet the elusive nature of many species makes estimating their abundance challenging. Abundance estimates of sea turtles, marine birds, and seals are usually made when breeding adults are ashore, while life stages spent at sea, including as juveniles, are often poorly sampled. We used a combination of high‐resolution satellite tracking (Fastloc‐GPS), uncrewed aerial vehicle (UAV) surveys, and capture‐mark‐recapture approaches to assess the abundance of immature hawksbill (Eretmochelys imbricata) and green turtles (Chelonia mydas) in a tidal lagoon of the Chagos Archipelago (Indian Ocean). We captured, marked, and released 50 turtles (48 hawksbill and 2 green turtles) prior to UAV surveys and used satellite tracking data from 27 immature turtles (25 hawksbill and 2 green turtles) to refine the estimated numbers of marked turtles available for resighting and those likely to have emigrated from the study area. We estimated a total of 339 turtles in the lagoon with a density variation at different tidal heights between 265 turtles km−2 at high water and 499 turtles km−2 at low water. Of these, 91% were hawksbills and 9% were green turtles. These hawksbill densities are the highest reported among 17 foraging sites recorded around the world and likely reflect successful long‐term protection of turtles in the Chagos Archipelago.

Neoctangium travassosi (Digenea: Microscaphidiidae) in sea turtles from South America

ABSTRACT Sea turtles are endangered animals that present cosmopolitan distribution. Anthropic actions have been considered important causes for the reduction of sea turtle population, but natural aspects such as parasitism may also contribute to their decline. This study aimed to report the occurrence of parasites in stranded dead sea turtles found in an area known as Potiguar Basin, northeastern Brazil, from 2010 to 2019. They were identified and classified according to the carapace length. At post-mortem analyses all organs were examined, parasites collected and morphologically identified. Ecological parasitic indexes as prevalence (P), mean intensity (MI) and mean abundance (MA) were calculated. A total of 80 Chelonia mydas and 5 Eretmochelys imbricata were assessed. Neoctangium travassosi was detected in both species presenting P = 20%, MI = 4.19 and MA = 0.84 for C. mydas and P = 60%, MI = 1.67 and MA = 1.0 for E. imbricata. This is the first report of N. travassosi parasitizing E. imbricata in South America. Finally, the retrieval of these parasites is a warning regarding the need for further studies to assess the impact of this parasitism on the health and conservation of sea turtles.

Preliminary analysis of microplastics from the main continental nesting beach of the hawksbill sea turtle (Eretmochelys imbricata) in Venezuela

Microplastics are an increasing threat to marine fauna and oceanic habitats, potentially affecting sea turtle nesting beaches. Hawksbill sea turtles (Eretmochelys imbricata) are a Critically Endangered species with decreasing population trends. There are several hawksbill rookeries in the southern Caribbean Sea, particularly on Los Garzos Beach, the main nesting site of continental Venezuela. A preliminary physical analysis of microplastics sampled from 10 sites on Los Garzos Beach reported high numbers (94 ± 2.5 items) of 14 different materials and colors. Microplastic counts at 10 sites averaged 1504 ± 405.61 items m-2, higher than other sea turtle nesting sites worldwide. There were no statistical differences in the concentration of microplastics at the sampled sites of Los Garzos Beach. However, the concentration of microplastics on this beach is higher at the midpoint of the falling tide (3520 ± 405.61 items m-2) and the top of the sea turtle nesting area (3840 ± 405.61 items m-2). We speculate that this debris could harm the nesting environment of hawksbill sea turtles in the region. While this study presents preliminary values for microplastics in an important hawksbill turtle nesting beach in Venezuela, it also serves as a baseline for long-term studies that can help determine the impact and sources of plastic pollution in sea turtle rookeries.

Dietary plasticity linked to divergent growth trajectories in a critically endangered sea turtle

Foraging habitat selection and diet quality are key factors that influence individual fitness and meta-population dynamics through effects on demographic rates. There is growing evidence that sea turtles exhibit regional differences in somatic growth linked to alternative dispersal patterns during the oceanic life stage. Yet, the role of habitat quality and diet in shaping somatic growth rates is poorly understood. Here, we evaluate whether diet variation is linked to regional growth variation in hawksbill sea turtles (Eretmochelys imbricata), which grow significantly slower in Texas, United States versus Florida, United States, through novel integrations of skeletal growth, gastrointestinal content (GI), and bulk tissue and amino acid (AA)-specific stable nitrogen (δ15N) and carbon (δ13C) isotope analyses. We also used AA δ15N ΣV values (heterotrophic bacterial re-synthesis index) and δ13C essential AA (δ13CEAA) fingerprinting to test assumptions about the energy sources fueling hawksbill food webs regionally. GI content analyses, framed within a global synthesis of hawksbill dietary plasticity, revealed that relatively fast-growing hawksbills stranded in Florida conformed with assumptions of extensive spongivory for this species. In contrast, relatively slow-growing hawksbills stranded in Texas consumed considerable amounts of non-sponge invertebrate prey and appear to forage higher in the food web as indicated by isotopic niche metrics and higher AA δ15N-based trophic position estimates internally indexed to baseline nitrogen isotope variation. However, regional differences in estimated trophic position may also be driven by unique isotope dynamics of sponge food webs. AA δ15N ΣV values and δ13CEAA fingerprinting indicated minimal bacterial re-synthesis of organic matter (ΣV &amp;lt; 2) and that eukaryotic microalgae were the primary energy source supporting hawksbill food webs. These findings run contrary to assumptions that hawksbill diets predominantly comprise high microbial abundance sponges expected to primarily derive energy from bacterial symbionts. Our findings suggest alternative foraging patterns could underlie regional variation in hawksbill growth rates, as divergence from typical sponge prey might correspond with increased energy expenditure and reduced foraging success or diet quality. As a result, differential dispersal patterns may infer substantial individual and population fitness costs and represent a previously unrecognized challenge to the persistence and recovery of this critically endangered species.

Destination Branding of Marine Ecotourism in Trenggalek Regency: A Study on Kili-Kili Beach Turtle Conservation

Kili-kili Beach Turtle Conservation is a tourist destination located on the south coast of East Java, precisely in Wonocoyo Village, Trenggalek Regency. There are approximately four types of sea turtle conservation, namely hawksbill turtles, gray turtles, leatherback turtles, and green turtles. As a new tourist destination, Kili-Kili Beach has a lot of potentials but has not been well developed. Conventional promotion methods have not been able to reach the target national and foreign tourists. Therefore, a promotion and marketing strategy is needed for Kili-Kili as an education-based tourism destination through the Internet (social media). Therefore, this service activity focuses on optimizing destination branding using the AISAS model (attention, interest, search, action, and share) through social media. The methods of implementing community service activities include 1) socialization of activity programs to local communities, 2) mentoring local communities in using social media as a medium for promoting tourist attractions, 3) training and creating social media content by involving POKMASWAS Turtle Conservation. This community service activity aims to promote the existence of marine ecotourism at Taman Kili-kili Beach, Trenggalek Regency as well as a turtle biota campaign by utilizing social media as a communication channel.

This baby turtle surprised scientists by swimming against the current.

Satellite transmitters help Cristina Miranda to understand the movements and habitats of endangered hawksbill sea turtles in the eastern Pacific Ocean. Satellite transmitters help Cristina Miranda to understand the movements and habitats of endangered hawksbill sea turtles in the eastern Pacific Ocean.

A Preliminary Report of Plastic Ingestion by Hawksbill and Green Turtles in the Saudi Arabian Red Sea.

(1) Background: Plastic pollution is a major environmental concern confronting marine animals. Sea turtles are considered a bio-indicator of plastic pollution, but there is little information regarding plastic ingestion by turtles in the Red Sea. With large-scale development projects being built along the Saudi Arabian coast, it is important to have a baseline for plastic ingestion before construction is complete. (2) Methods: Ten deceased sea turtles (four hawksbill and six green turtles) were collected along the Saudi Arabian coastline. Necropsies were conducted, and the entire gastrointestinal tracts were extracted and the contents were passed through a 1 mm mesh sieve. (3) Results: We found that 40% of the turtles in this study had ingested plastics. Thread-like plastics were the most common plastic category, and multi-colored was the most prevalent color category. (4) Conclusions: Monitoring of the plastic ingestion by marine megafauna should be conducted as a long-term assessment of the developments' impacts. Additionally, conservation efforts should be focused on removing plastics (namely ghost nests and fishing lines) from the reefs and reducing the amount of plastic entering the sea.

Increased Prevalence and New Evidence of Multi-Species Chelonid Herpesvirus 5 (ChHV5) Infection in the Sea Turtles of Mabul Island, Borneo.

Fibropapillomatosis (FP) is a debilitating tumor disease affecting all species of sea turtles globally. The most probable etiological agent for FP is the chelonid herpesvirus 5 (ChHV5). A 2015-2016 field survey of the sea turtles at Mabul Island, Sabah, Malaysia, found three green turtles (Chelonia mydas) with FP tumors. However, the presence of ChHV5 was confirmed in 7.8% (9/115) green turtles and was absent (0/16) in the hawksbill (Eretmochelys imbricata) turtles, as determined through molecular approaches. Subsequent to this, we managed to conduct field sampling of sea turtles in November 2019, just prior to the pandemic lockdown. Here, we aim to determine the extent of ChHV5 infection, and whether the virus has spread to other species of sea turtles around Mabul Island after the first reports of ChHV5 and FP. A total of 69 tissue samples were obtained from green (63), hawksbill (5), and olive ridley (Lepidochelys olivacea) (1) turtles in November 2019. We observed only one green turtle that exhibited FP tumors. To determine the presence of ChHV5, viral DNA was isolated from all the tissue samples, and polymerase chain reaction (PCR) analysis targeting three highly conserved regions of the virus, i.e., the capsid protein gene, glycoprotein H gene, and glycoprotein B gene, was performed. Out of 63 green turtles, 27 were positive for the presence of the virus. The prevalence of ChHV5 in the green turtles showed an increase of 42.9% as compared to the previous sampling conducted in 2015-2016. Additionally, for the first time, three out of the five hawksbill turtles, and one olive ridley turtle, were also PCR-positive for the virus. In conclusion, this study reveals that there has been an increase in ChHV5 infection among turtles in Mabul Island over the last 3 years. ChHV5 should be considered a potential threat, and mitigation efforts should be taken to prevent the spread of infection among the endangered sea turtles of Mabul Island and surrounding islands within the Coral Triangle.

Trophic behavior of inorganic elements in nesting sea turtles (Chelonia mydas, Eretmochelys imbricata, and Caretta caretta) in Quintana Roo: Biomagnification and biodilution effect in blood and scute tissues

The biomagnification and biodilution of inorganic pollutants, have a close correlation on the structure and function of trophic change behavior; sea turtles represent an excellent bioindicator model to identify their impact in marine ecosystems. To understand pollution effects on marine ecosystems, we quantified the bioconcentration of 50 inorganic elements in the blood and scute tissues of three nesting species of sea turtles (Chelonia mydas, Eretmochelys imbricata and Caretta caretta), collected in Quintana Roo State from July 2017 to August 2018. As a general trend, essential mineral elements with toxic potential showed the highest concentrations in both tissues; significant increase concentration of arsenic, mercury, and cerium levels was observed with increasing trophic levels indicating its biomagnification while a significant decrease in manganese and bismuth showed a biodilution effect. We expect that our findings can be used as baseline data in future biomonitoring and contamination risk assessment programs in the region.