Pivotal temperature for loggerhead turtles (Caretta caretta) from Kyparissia Bay, Greece

2002 ◽  
Vol 80 (12) ◽  
pp. 2118-2124 ◽  
Author(s):  
N Mrosovsky ◽  
Stephanie Kamel ◽  
Alan F Rees ◽  
D Margaritoulis
Keyword(s):  
United States ◽  
Sex Ratio ◽  
Constant Temperature ◽  
Sea Turtles ◽  
Caretta Caretta ◽  
The United States ◽  
Loggerhead Sea Turtles ◽  
Incubation Duration ◽  
Different Populations ◽  
Pivotal Temperature

Pivotal temperature (the constant temperature giving 50% of each sex) for two clutches of loggerhead sea turtles (Caretta caretta) from Kyparissia Bay, Greece, was 29.3°C. Pivotal incubation duration (the time from laying to hatching giving 50% of each sex) was 52.6 days. These values are close to those obtained for this species in Brazil and the United States, providing further evidence that these characteristics are relatively conservative in different populations. Methodological differences between different experiments and limitations on accuracy of equipment make the detection of small differences problematic. Comparison of incubation durations in the field with the pivotal durations obtained here suggest that hatchling sex ratio on some Mediterranean beaches is female biased but probably varies considerably within this region.

Temporal and Spatial Trends of Perfluorinated Compounds in Juvenile Loggerhead Sea Turtles (Caretta caretta) along the East Coast of the United States

2010 ◽  
Vol 44 (13) ◽  
pp. 5202-5209 ◽  
Author(s):  
Steven G. O’Connell ◽  
Michael Arendt ◽  
Al Segars ◽  
Tricia Kimmel ◽  
Joanne Braun-McNeill ◽  
...  
Keyword(s):  
United States ◽  
East Coast ◽  
Sea Turtles ◽  
Caretta Caretta ◽  
The United States ◽  
Perfluorinated Compounds ◽  
Loggerhead Sea Turtles ◽  
Spatial Trends ◽  
Temporal And Spatial ◽  
Temporal And Spatial Trends

scholarly journals Chronic debilitation in stranded loggerhead sea turtles (Caretta caretta) in the southeastern United States: Morphometrics and clinicopathological findings

PLoS ONE ◽  
2018 ◽  
Vol 13 (7) ◽  
pp. e0200355 ◽  
Author(s):  
Nicole I. Stacy ◽  
Jennifer M. Lynch ◽  
Michael D. Arendt ◽  
Larisa Avens ◽  
Joanne Braun McNeill ◽  
...  
Keyword(s):  
United States ◽  
Sea Turtles ◽  
Southeastern United States ◽  
Caretta Caretta ◽  
Loggerhead Sea Turtles ◽  
Clinicopathological Findings

Female-biased sex ratio of immature loggerhead sea turtles inhabiting the Atlantic coastal waters of Florida

1991 ◽  
Vol 69 (12) ◽  
pp. 2973-2977 ◽  
Author(s):  
Thane Wibbels ◽  
R. Erik Martin ◽  
David W. Owens ◽  
Max S. Amoss Jr.
Keyword(s):  
Sex Ratio ◽  
Coastal Waters ◽  
Sex Allocation ◽  
Sea Turtles ◽  
The United States ◽  
Loggerhead Sea Turtles ◽  
Blood Samples ◽  
Sex Allocation Theory ◽  
Biased Sex Ratio ◽  
Atlantic Coastal

The sex ratio of immature loggerhead sea turtles, Caretta caretta, inhabiting the Atlantic coastal waters of Florida was investigated. Blood samples were obtained from 223 turtles that were captured in the intake channel of a power plant on Hutchinson Island. A serum androgen sexing technique was utilized to sex individual turtles. The sex ratio of the turtles (2.1 female: 1.0 male) differed significantly from 1:1 and thus appears to differ from predictions of sex allocation theory. These observations are consistent with those of a previous study, and collectively the results suggest that the sex ratio of immature C. caretta inhabiting the Atlantic coastal waters of the United States is significantly female biased: approximately two females per male.

Validation of incubation duration as an index of the sex ratio of hatchling sea turtles

1999 ◽  
Vol 77 (5) ◽  
pp. 831-835 ◽  
Author(s):  
N Mrosovsky ◽  
Cecília Baptistotte ◽  
Matthew H Godfrey
Keyword(s):  
Sex Ratio ◽  
High Temperatures ◽  
Low Temperatures ◽  
Sea Turtles ◽  
Sex Ratios ◽  
Caretta Caretta ◽  
Turtle Species ◽  
Loggerhead Turtles ◽  
Incubation Duration

One method of estimating the sex ratio of hatchling sea turtles is to use the incubation duration. Long and short durations imply low and high temperatures, respectively. In turtle species whose sex is determined by temperature, males are produced at low temperatures and females at high temperatures. This study assesses the validity of using incubation duration to estimate the sex ratio. Samples of hatchling loggerhead turtles (Caretta caretta) were collected from nests with known incubation durations, and sex was ascertained by means of histology. The sex ratio of groups of nests determined by histology was compared with that predicted from previous relationships between incubation duration and sex ratio. For conditions causing relatively long or relatively short incubation durations, the sex ratio could be predicted with considerable accuracy. For conditions causing durations nearer to the pivotal duration (that which gives 50% of each sex), predictions could be off by 10%, depending on the distribution of incubation durations, but it was still possible to determine whether ratios were highly skewed or approximately balanced. Estimating sex ratios of hatchling sea turtles from incubation durations is simple, cheap, and can be used retrospectively.

Geographical variation of persistent organic pollutants in eggs of threatened loggerhead sea turtles (Caretta caretta) from southeastern United States

2011 ◽  
Vol 30 (7) ◽  
pp. 1677-1688 ◽  
Author(s):  
Juan José Alava ◽  
Jennifer M. Keller ◽  
Jeanette Wyneken ◽  
Larry Crowder ◽  
Geoffrey Scott ◽  
...  
Keyword(s):  
United States ◽  
Organic Pollutants ◽  
Persistent Organic Pollutants ◽  
Geographical Variation ◽  
Sea Turtles ◽  
Southeastern United States ◽  
Caretta Caretta ◽  
Loggerhead Sea Turtles

Critical periods and pivotal temperatures for sexual differentiation in loggerhead sea turtles

1982 ◽  
Vol 60 (5) ◽  
pp. 1012-1016 ◽  
Author(s):  
C. L. Yntema ◽  
N. Mrosovsky
Keyword(s):  
Embryonic Development ◽  
Sexual Differentiation ◽  
Thermal Effects ◽  
Critical Period ◽  
Sea Turtles ◽  
Caretta Caretta ◽  
Critical Periods ◽  
Loggerhead Sea Turtles ◽  
Definition Of ◽  
Pivotal Temperature

Eggs of loggerhead sea turtles, Caretta caretta, were incubated at constant temperatures ranging from 24 to 34 °C. At temperatures of 32 °C or above all embryos developed into females as judged by histology of the gonads. At 28 °C or below all developed into males. At 30 °C there were approximately equal numbers of both sexes; 30 °C therefore is the pivotal temperature for the thermal effects on sexual differentiation in this population of turtles. The direction of sexual differentiation is not determined by temperature throughout incubation but by the levels prevailing during a critical period. Experiments with temporary alterations of temperature, either upwards or downwards from the pivotal value, localized the critical period to somewhere between stages 12 and 22 of embryonic development. Definition of the critical period in sea turtles should prove useful both in further work on the theoretical aspects of the phenomenon and in conservation programmes for sea turtles.

Pivotal temperatures for loggerhead turtles (Caretta caretta) from northern and southern nesting beaches

1988 ◽  
Vol 66 (3) ◽  
pp. 661-669 ◽  
Author(s):  
N. Mrosovsky
Keyword(s):  
North Carolina ◽  
Incubation Temperature ◽  
Caretta Caretta ◽  
The United States ◽  
Loggerhead Sea Turtles ◽  
The North ◽  
Significant Difference ◽  
Incubation Duration ◽  
Southern Florida ◽  
Nesting Beaches

The pivotal incubation temperature (that giving 50% of each sex) was estimated for two clutches of eggs from loggerhead sea turtles (Caretta caretta) nesting in each of three areas along the east coast of the United States: North Carolina, Georgia, and southern Florida. All pivotal temperatures were close to 29.0 °C. There was a significant difference between the pivotal temperatures of the two clutches from Florida. As an index of beach temperature, data on incubation durations in the three areas were collated and analysed: even during the warmest part of the season, incubation took about 6 days longer in North Carolina than in Georgia, and about 10–14 days longer than in Florida. Since there was no evidence that pivotal temperatures in North Carolina were lower than those of turtles nesting further south, it is likely that a higher percentage of males are produced on the North Carolina beaches, but data on pivotal temperatures of additional clutches are needed before this prediction can be made with confidence. The possible use of incubation duration for estimating sex ratios of hatchlings is discussed.

Health and nutrition of loggerhead sea turtles ( Caretta caretta ) in the southeastern United States

2021 ◽  
Author(s):  
Christine M. Molter ◽  
Terry M. Norton ◽  
Lisa A. Hoopes ◽  
Steven E. Nelson ◽  
Michelle Kaylor ◽  
...  
Keyword(s):  
United States ◽  
Sea Turtles ◽  
Southeastern United States ◽  
Caretta Caretta ◽  
Loggerhead Sea Turtles ◽  
Health And Nutrition

Development and pre-validation of a testosterone enzyme immunoassay (EIA) for predicting the sex ratio of immature loggerhead sea turtles (Caretta caretta) recovered along the western coast of the central Adriatic Sea

2013 ◽  
Vol 161 (1) ◽  
pp. 165-171 ◽  
Author(s):  
Paolo Cocci ◽  
Luca Bracchetti ◽  
Valeria Angelini ◽  
Matteo Bucchia ◽  
Sauro Pari ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Enzyme Immunoassay ◽  
Adriatic Sea ◽  
Sea Turtles ◽  
Caretta Caretta ◽  
Western Coast ◽  
Loggerhead Sea Turtles

Sex ratio of hatchling loggerhead sea turtles: data and estimates from a 5-year study

1992 ◽  
Vol 70 (3) ◽  
pp. 530-538 ◽  
Author(s):  
N. Mrosovsky ◽  
Jane Provancha
Keyword(s):  
Global Warming ◽  
Sex Ratio ◽  
Sea Turtles ◽  
Sex Ratios ◽  
Caretta Caretta ◽  
Loggerhead Sea Turtles ◽  
Loggerhead Turtles ◽  
Biased Sex Ratio ◽  
Nesting Season

Hatchling loggerhead sea turtles (Caretta caretta) were collected over three nesting seasons from a rookery at Cape Canaveral, Florida. From data on the distribution of nests over the season, we estimated that 92.6–96.7, 94.7–99.9, and 87.0–89.0% of the hatchlings produced on this beach in 1986, 1987, and 1988, respectively, were females. These skewed sex ratios were consistent with the fact that for most of the season, sand temperatures were above the pivotal level for loggerhead turtles. The present results show that the female-biased sex ratio reported previously by these authors for the 1986 nesting season at this site was not an isolated, atypical event. In addition to a total of 3 years of sampling for sex ratio, measurements of beach temperatures at the depth of turtle nests were extended to cover 5 years. These temperatures were commonly above the pivotal level. The strongly female-biased hatchling sex ratio found in this population of loggerhead turtles poses theoretical challenges. It may also complicate conservation efforts, since global warming might be expected to skew the sex ratio still further toward females.

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