scholarly journals Ascension Island as a mid-Atlantic developmental habitat for juvenile hawksbill turtles

2014 ◽  
Vol 97 (4) ◽  
pp. 813-820 ◽  
Author(s):  
Sam B. Weber ◽  
Nicola Weber ◽  
Brendan J. Godley ◽  
Tara Pelembe ◽  
Stedson Stroud ◽  
...  
Keyword(s):  
Benthic Algae ◽  
Chelonia Mydas ◽  
Small Population ◽  
Future Research ◽  
Home Ranges ◽  
Utilization Distribution ◽  
Eretmochelys Imbricata ◽  
Ascension Island ◽  
Minimum Residence Time ◽  
Hawksbill Turtles

Ascension Island in the South Atlantic Ocean is renowned for its globally-important nesting population of green turtles (Chelonia mydas) that has been the subject of long-term research. By comparison, very little is known about the apparently small population of hawksbill turtles (Eretmochelys imbricata) that have been recorded in its waters, thousands of kilometres from known nesting beaches. Here, we collate 10 years of in-water tagging data, opportunistic public sighting records and underwater observations to provide a baseline for future research, and present preliminary data on habitat use derived from two individuals fitted with GPS transmitters. Although public sightings were inevitably biased towards popular recreation areas, the resulting distribution suggests that hawksbill turtles occur year round in Ascension Island's waters along the entire 65 km of coastline. Hawksbills were observed feeding on benthic algae and encrusting sponges, and were frequently seen scavenging on fish discards around the Island's pier at night aided by anthropogenic lighting. Between 2003 and 2013, 35 turtles were captured, measured, tagged and then released. Curved carapace lengths ranged from 33.5 to 85 cm (mean = 48.8 cm) indicating that most (if not all) individuals encountered around Ascension are post-pelagic juveniles. Four individuals were recaptured at least once giving a mean minimum residence time of 4.2 yr (range: 2.8–7.3 yr) and a mean growth rate of 2.8 cm yr−1. Turtles fitted with Fastloc™ GPS devices remained at Ascension Island for the duration of the study (>90 days) and occupied restricted home ranges with an average area of 2.5 km2 and an average ‘core use area’ (50% utilization distribution) of 0.05 km2. Together, these results suggest that Ascension Island serves as a mid-Atlantic developmental habitat for benthic-feeding, juvenile hawksbill turtles on extended oceanic migrations before recruiting to their adult foraging grounds, likely to be located in Brazil or tropical West Africa.

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

PLoS ONE ◽  
2021 ◽  
Vol 16 (7) ◽  
pp. e0253916
Author(s):  
Chelsea E. Clyde-Brockway ◽  
Christina R. Ferreira ◽  
Elizabeth A. Flaherty ◽  
Frank V. Paladino
Keyword(s):  
Sea Turtles ◽  
Multiple Reaction Monitoring ◽  
Chelonia Mydas ◽  
Sea Turtle ◽  
Lipid Classes ◽  
Plasma Samples ◽  
Lipid Profiling ◽  
Eretmochelys Imbricata ◽  
Species Specific ◽  
Hawksbill Turtles

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.

Intake and excretion of arsenicals in green (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata)

2011 ◽  
Vol 8 (1) ◽  
pp. 19 ◽  
Author(s):  
Tetsuro Agusa ◽  
Kozue Takagi ◽  
Todd W. Miller ◽  
Reiji Kubota ◽  
Yasumi Anan ◽  
...  
Keyword(s):  
Feeding Behaviour ◽  
Chelonia Mydas ◽  
Water Soluble ◽  
Marine Animals ◽  
Eretmochelys Imbricata ◽  
Accumulation Pattern ◽  
Turtle Species ◽  
Green Turtles ◽  
Hawksbill Turtles ◽  
Prey Items

Environmental context Although among higher marine animals, relatively high concentration of arsenic and unique distribution of arsenic compounds are found in green (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata), the accumulation mechanism remains unknown. We examined the accumulation of arsenicals in two turtles from the standpoint of short- and long-term intake and excretion and found that prey items might be important for the arsenic accumulation. This study can provide useful information on the accumulation pattern of arsenic speciation in sea turtles. Abstract We analysed arsenic (As) compounds in the stomach and intestine contents, bile and urine of green (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata) to understand As accumulation through intake and excretion. Stable isotopes of δ15N and δ13C were also measured for understanding the feeding behaviour dependent accumulation of As. Major As species in gastrointestinal contents were unknown water-soluble As, followed by unextracted As. Concentrations of AB and DMA in the tissues were higher than those in the stomach contents (prey items), indicating high bioaccumulation of these arsenicals. In green turtles, AB concentration was high in bile and increased throughout the gastrointestinal tract, suggesting significant biliary excretion of AB. δ15N was positively correlated with AB level in green turtles, whereas a negative relationship between residual As and δ15N was observed in hawksbill turtles. This study indicates feeding behaviour-dependent accumulation of As compounds in both turtle species for the first time.

Green Sea Turtles Stranded by Cyclone Kathy on the South-Westeern Coast of the Culf of Carpentaria

1985 ◽  
Vol 12 (3) ◽  
pp. 523 ◽  
Author(s):  
CJ Limpus ◽  
PC Reed
Keyword(s):  
Breeding Season ◽  
Chelonia Mydas ◽  
Olive Ridley ◽  
Eretmochelys Imbricata ◽  
Lepidochelys Olivacea ◽  
Green Sea Turtles ◽  
Green Turtles ◽  
Previous Season ◽  
Hawksbill Turtles ◽  
Principal Species

Cyclone Kathy on 23 March 1984 stranded many green turtles, Chelonia mydas, on the coast adjacent to the Sir Edward Pellew Is. It is estimated that over 1000 were thrown up by the storm surge and that over 500 were left stranded by the receding waters, including migrants from the Raine I. rookery. These turtles, which were predominately large females, had been feeding close inshore on seagrass. Of the mature females sampled, 62% were preparing to breed in the next breeding season but none had bred in the previous season. The flatback turtle, Chelonia depressa, the principal species breeding on the Sir Edward Pellew Is, was not involved in the stranding. Hawksbill turtles, Eretmochelys imbricata, and olive ridley turtles, Lepidochelys olivacea, which occur in the deeper offshore waters were also not stranded. Some of the rescued turtles were subsequently recaptured nesting at Raine I.

scholarly journals Effects of a power plant closure on home ranges of green turtles in an urban foraging area

2020 ◽  
Vol 41 ◽  
pp. 265-277 ◽  
Author(s):  
T Eguchi ◽  
J Bredvik ◽  
S Graham ◽  
R LeRoux ◽  
B Saunders ◽  
...  
Keyword(s):  
Power Plant ◽  
Green Turtle ◽  
Chelonia Mydas ◽  
Home Ranges ◽  
Utilization Distribution ◽  
Green Turtles ◽  
Foraging Area ◽  
San Diego Bay ◽  
Conservation Actions ◽  
Satellite Transmitters

A natural experiment was conducted to determine effects of a fossil-fueled power plant on home ranges of east Pacific green turtles Chelonia mydas in an urban foraging ground. The power plant, located in south San Diego Bay, California, USA, co-existed with a resident foraging aggregation of ~60 green turtles for ~50 yr. It was decommissioned during a long-term green turtle monitoring study, thus providing a rare opportunity to evaluate how the cessation of warm-water effluent affected turtle movements and habitat use in the area. During pre- and post-decommissioning of the power plant, 7 and 23 green turtles, respectively, were equipped with GPS-enabled satellite transmitters. Useful data were obtained from 17 turtles (4 for pre- and 13 for post-decommissioning). Core use areas (50% utilization distribution [UD]) increased from 0.71 to 1.37 km2 after the power plant decommissioning. Increase in post-power plant 50% UD was greater during nighttime (0.52 to 1.44 km2) than daytime (1.32 to 1.43 km2). Furthermore, UDs moved from the effluent channel to an area closer to seagrass pastures, a presumed foraging habitat of the turtles. The observed expansion of green turtle home ranges may increase turtle-human interactions, such as boat strikes, within the foraging ground; this underscores how seemingly innocuous human actions contribute to inadvertent consequences to wildlife. Possible management and conservation actions include increasing awareness of the public regarding turtle presence in the area through signage and education as well as legislating for a reduction in boat speeds in select areas of the bay.

Serum testosterone and estradiol-17ß levels during the peak period in a year-round Hawksbill Turtle Eretmochelys imbricata L. nesting population

2007 ◽  
Vol 13 (3) ◽  
pp. 151 ◽  
Author(s):  
K. A. Dobbs ◽  
J. D. Miller ◽  
D. W. Owens ◽  
A. M. Landry Jr.
Keyword(s):  
Austral Summer ◽  
Serum Testosterone ◽  
Marine Turtle ◽  
Gonadal Hormone ◽  
Future Research ◽  
Hormone Concentration ◽  
Peak Period ◽  
Eretmochelys Imbricata ◽  
Hawksbill Turtles ◽  
Nesting Season

Serum testosterone (T) and estradiol-17� (E2 ) concentrations were determined for 95 Hawksbill Turtles Eretmochelys imbricate nesting at Milman Island, northern Great Barrier Reef, Australia. This information describes gonadal hormone concentration during the Austral summer months for peak nesting in an E. imbricata population that nest year-round. A total of 173 samples was collected from 95 turtles, with 39 turtles sampled sequentially within their nesting cycle (n = 117 samples) and the remainder sampled at random. E2 -levels were measured from seven turtles sampled sequentially within their nesting cycle (n = 31 samples). T-Ievels ranged from 0 to 7 520 pg/ml; E2-Ieveis varied between 0.0 and 119.0 pg/ml. Peak T-Ievels in turtles sampled sequentially within their nesting cycle occurred after laying clutch number two or three while E2-levels peaked after clutch number one or two; levels of both hormones decreased thereafter. T- and E2-levels decreased monthly (December to March) within a nesting season. Based on T-Ievels, the greatest proportion (58%) of turtles began their nesting cycle in December. Turtles in the middle of their nesting cycle were found in equal proportions (27?35%) throughout the Austral summer months. Turtles at the end of their nesting cycle were most frequent (61%) in March. The implications of these results for future research and for managing access to islands with year-round marine turtle nesting are discussed.

Comparison of plasma androgen profiles in green and hawksbill sea turtles inhabiting Queensland waters

2004 ◽  
Vol 52 (3) ◽  
pp. 293 ◽  
Author(s):  
Tim S. Jessop ◽  
Colin J. Limpus ◽  
Joan M. Whittier
Keyword(s):  
Seasonal Variation ◽  
Phase Shift ◽  
Chelonia Mydas ◽  
Wild Populations ◽  
Ontogenetic Changes ◽  
Eretmochelys Imbricata ◽  
Green Turtles ◽  
Hawksbill Turtles ◽  
Delayed Phase ◽  
Androgen Levels

Investigations were made into profiles of plasma androgens (combined testosterone and 5α-dihydrotestosterone) in green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) turtles inhabiting waters off Queensland, Australia. First, we documented the occurrence of sex-based and ontogenetic changes in plasma androgen of immature green and hawksbill turtles occurring in wild populations. Specifically, androgen levels are increased in pubescent individuals and adults of both species and sexes. Second, we measured seasonal variation in plasma androgen profiles of adult male green and hawksbill turtles. Third, we compared plasma androgens of post-nesting green and hawksbill turtles. As for previous studies on captive green turtles, our data indicate that wild populations of green turtles also show a prenuptial spermatogenic pattern, in which plasma androgen levels rise and peak prior to migration and courtship. However, our data from male hawksbill turtles are in contrast to this pattern and provide some evidence to suggest that a delayed phase shift may occur in this population. Unlike male green turtles, male hawksbill turtles in this study all showed signs of physiological preparation for breeding.

scholarly journals Sea turtles of Madagascar – their status, exploitation and conservation

Oryx ◽  
1994 ◽  
Vol 28 (1) ◽  
pp. 51-61 ◽  
Author(s):  
Berthin Rakotonirina ◽  
Andrew Cooke
Keyword(s):  
Coastal Waters ◽  
Sea Turtles ◽  
Loggerhead Turtle ◽  
Chelonia Mydas ◽  
Dermochelys Coriacea ◽  
Olive Ridley ◽  
Eretmochelys Imbricata ◽  
Lepidochelys Olivacea ◽  
Average Size ◽  
Hawksbill Turtles

Five species of sea turtles are known from Madagascar's coastal waters. Fishermen on the western and south-western coasts take green turtle Chelonia mydas, loggerhead turtle Caretta caretta and olive ridley Lepidochelys olivacea for their meat. The hawksbill turtle Eretmochelys imbricata is taken mainly for its shell and for making stuffed specimens while the leatherback Dermochelys coriacea is seldom caught. Anecdotal evidence of fishermen and dealers in turtle products, measurement of captured animals and personal observations of the authors all point to declines in numbers and average size for green and hawksbill turtles, coupled with marked declines in nesting rates for these and the olive ridley.

scholarly journals An assessment of the marine turtle fishery in Grenada, West Indies

Oryx ◽  
2007 ◽  
Vol 41 (3) ◽  
pp. 330-336 ◽  
Author(s):  
S. Grazette ◽  
J.A. Horrocks ◽  
Paul E. Phillip ◽  
Crafton J. Isaac
Keyword(s):  
Breeding Season ◽  
Landing Site ◽  
Chelonia Mydas ◽  
Marine Turtle ◽  
Catch Per Unit Effort ◽  
Eretmochelys Imbricata ◽  
Green Turtles ◽  
Hawksbill Turtles ◽  
Relative Scarcity ◽  
Made In

AbstractThe marine turtle fishery of Grenada was assessed using interviews with marine turtle fishermen and by examination of turtle catch data from a major landing site. An estimated 782 turtles, mainly Endangered green turtles Chelonia mydas and Critically Endangered hawksbill turtles Eretmochelys imbricata, were caught around Grenada and its sister island Carriacou each year between 1996 and 2001 during an annual 8-month open season, with only a small percentage being officially recorded at a landing site. Turtles were primarily caught with nets and spearguns, with more green turtles caught by net fishermen and more hawksbill turtles by spear fishermen. Catch per unit effort data suggested that relative abundance had declined since the previous estimate was made in 1969. Few adult green or loggerhead turtles Caretta caretta were caught, indicating the relative scarcity of this size class of these two species around Grenada. Adult-sized hawksbill turtles were caught regularly, with larger adults being caught in the non-breeding months of the open season than in the breeding months. A higher percentage of adult hawksbill turtles present during the breeding season are likely to be animals that nest in Grenada, and their smaller size may result from historically heavy fishing pressure. The larger sized adults caught during the non-breeding season are likely to be animals that forage around Grenada but breed elsewhere in the Caribbean where they are protected.

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