Pivotal and beach temperatures for hawksbill turtles nesting in Antigua

1992 ◽  
Vol 70 (10) ◽  
pp. 1920-1925 ◽  
Author(s):  
N. Mrosovsky ◽  
Anna Bass ◽  
Lynn A. Corliss ◽  
James I. Richardson ◽  
Thelma H. Richardson
Keyword(s):  
Sex Ratios ◽  
Eretmochelys Imbricata ◽  
Hawksbill Turtles ◽  
Pivotal Temperature

Eggs of hawksbill turtles, Eretmochelys imbricata, from Antigua were incubated at constant tempe ratures. The pivotal temperature (the temperature at which 50% of each sex is produced) for the sample was estimated to be 29.2 °C. Sand temperatures at the depth of turtle nests were recorded over two nesting seasons at Pasture Bay, Antigua. Although sand temperatures were sometimes higher than the pivotal temperature, more often they were lower. On this basis, it is unlikely that hatchling hawksbill turtles in this area have the highly female-biased sex ratios reported for some other reptiles.

Pivotal temperature and predicted sex ratios for hatchling hawksbill turtles from Brazil

1999 ◽  
Vol 77 (9) ◽  
pp. 1465-1473 ◽  
Author(s):  
Matthew H Godfrey ◽  
Adriana F D'Amato ◽  
Maria  Marcovaldi ◽  
N Mrosovsky
Keyword(s):  
Low Temperatures ◽  
Sex Ratios ◽  
Sea Turtle ◽  
Temperature Dependent ◽  
Eretmochelys Imbricata ◽  
Conservation Implications ◽  
Incubation Duration ◽  
Incubation Temperatures ◽  
Hawksbill Turtles ◽  
Pivotal Temperature

Like all other species of sea turtle, the hawksbill turtle (Eretmochelys imbricata) exhibits temperature-dependent sexual differentiation, with high incubation temperatures producing females and low temperatures producing males. Relatively little is known about the sex ratios of hatchlings produced by nesting populations of hawksbill turtles. Here we estimate the overall seasonal sex ratios of hatchling hawksbill turtles produced in Bahia, Brazil, during 6 nesting seasons, based on incubation durations, pivotal temperature, and pivotal incubation duration. The overall sex ratio of hatchlings produced in Bahia from 1991-1992 through 1996-1997 was estimated to be >90% female, which is more female-biased than estimated sex ratios of hatchling loggerhead turtles from Bahia and Florida, U.S.A. The biological and conservation implications of skewed sex ratios are discussed.

scholarly journals Feminization of hawksbill turtle hatchlings in the twenty-first century at an important regional nesting aggregation

2021 ◽  
Vol 44 ◽  
pp. 149-158
Author(s):  
M Chatting ◽  
S Hamza ◽  
J Al-Khayat ◽  
D Smyth ◽  
S Husrevoglu ◽  
...  
Keyword(s):  
Climate Change ◽  
Sex Ratios ◽  
First Century ◽  
Climate Data ◽  
Temperature Dependent ◽  
Eretmochelys Imbricata ◽  
Climate Forecasts ◽  
The Face ◽  
Incubation Temperatures ◽  
Hawksbill Turtles

Projected climate change is forecasted to have significant effects on biological systems worldwide. Marine turtles in particular may be vulnerable, as the sex of their offspring is determined by their incubating temperature, termed temperature-dependent sex determination. This study aimed to estimate historical, and forecast future, primary sex ratios of hawksbill turtle Eretmochelys imbricata hatchlings at an important nesting ground in northeastern Qatar. Incubation temperatures from the Arabian/Persian Gulf were measured over 2 nesting seasons. Climate data from same period were regressed with nest temperatures to estimate incubation temperatures and hatchling sex ratios for the site from 1993 to 2100. Future hatchling sex ratios were estimated for 2 climate forecasts, one mid-range (SSP245) and one extreme (SSP585). Historical climate data showed female-biased sex ratios of 73.2 ± 12.1% from 1993 to 2017. Female biases from 2018 to 2100 averaged 85.7% ± 6.7% under the mid-range scenario and 87.9% ± 5.4% under the high-range scenario. In addition, predicted female hatchling production was >90% from 2054 and 2052 for SSP245 and SSP585, respectively. These results show that hawksbill primary sex ratios in Qatar are at risk of significant feminization by the year 2100 and that hawksbill turtle incubation temperatures in an extreme, understudied environment are already comparable to those predicted in tropical rookeries during the latter half of the 21st century. These results can help conservationists predict primary sex ratios for hawksbill turtles in the region in the face of 21st-century climate change.

scholarly journals Natal foraging philopatry in eastern Pacific hawksbill turtles

2017 ◽  
Vol 4 (8) ◽  
pp. 170153 ◽  
Author(s):  
Alexander R. Gaos ◽  
Rebecca L. Lewison ◽  
Michael P. Jensen ◽  
Michael J. Liles ◽  
Ana Henriquez ◽  
...  
Keyword(s):  
Genetic Research ◽  
Eastern Pacific ◽  
Marine Turtle ◽  
Natal Philopatry ◽  
Eretmochelys Imbricata ◽  
Turtle Species ◽  
Marine Turtles ◽  
Complex Processes ◽  
Natal Homing ◽  
Hawksbill Turtles

The complex processes involved with animal migration have long been a subject of biological interest, and broad-scale movement patterns of many marine turtle populations still remain unresolved. While it is widely accepted that once marine turtles reach sexual maturity they home to natal areas for nesting or reproduction, the role of philopatry to natal areas during other life stages has received less scrutiny, despite widespread evidence across the taxa. Here we report on genetic research that indicates that juvenile hawksbill turtles ( Eretmochelys imbricata ) in the eastern Pacific Ocean use foraging grounds in the region of their natal beaches, a pattern we term natal foraging philopatry. Our findings confirm that traditional views of natal homing solely for reproduction are incomplete and that many marine turtle species exhibit philopatry to natal areas to forage. Our results have important implications for life-history research and conservation of marine turtles and may extend to other wide-ranging marine vertebrates that demonstrate natal philopatry.

scholarly journals Nesting ecology of hawksbill turtles, Eretmochelys imbricata, in an extreme environmental setting

PLoS ONE ◽  
2018 ◽  
Vol 13 (9) ◽  
pp. e0203257 ◽  
Author(s):  
Mark Chatting ◽  
David Smyth ◽  
Ibrahim Al-Maslamani ◽  
Jeffrey Obbard ◽  
Mehsin Al-Ansi ◽  
...  
Keyword(s):  
Nesting Ecology ◽  
Eretmochelys Imbricata ◽  
Environmental Setting ◽  
Hawksbill Turtles

Single nucleotide polymorphism markers for genotyping hawksbill turtles (Eretmochelys imbricata)

2019 ◽  
Vol 12 (3) ◽  
pp. 353-356
Author(s):  
Shreya M. Banerjee ◽  
Lisa M. Komoroske ◽  
Amy Frey ◽  
Brittany Hancock-Hanser ◽  
Phillip A. Morin ◽  
...  
Keyword(s):  
Single Nucleotide Polymorphism ◽  
Nucleotide Polymorphism ◽  
Single Nucleotide ◽  
Eretmochelys Imbricata ◽  
Hawksbill Turtles

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.

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