Sex ratio of loggerhead sea turtles hatching on a Florida beach

1989 ◽  
Vol 67 (10) ◽  
pp. 2533-2539 ◽  
Author(s):  
N. Mrosovsky ◽  
Jane Provancha
Keyword(s):  
Global Warming ◽  
Sex Ratio ◽  
Sea Turtles ◽  
Caretta Caretta ◽  
Loggerhead Sea Turtles ◽  
Histological Criteria ◽  
The Future ◽  
Loggerhead Turtles ◽  
Nesting Season

Hatchling loggerhead sea turtles (Caretta caretta) were collected over the summer nesting season from a major rookery at Cape Canaveral, Florida, in 1986. Sex was assessed using histological criteria. From data on the distribution of nests over the season, we estimated that in 1986, > 93% of the hatchlings produced on this beach were females. This huge bias toward females is consistent with sand temperatures at the depth of turtle nests; for most of the season these temperatures were above the pivotal level for loggerhead turtles. The results suggest that in the future, turtles in this area will encounter difficulty in overcoming the feminizing effect of global warming and that biologists should pay more attention to the beaches at the northern end of the loggerhead's nesting range.

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.

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.

scholarly journals Female loggerhead sea turtles ( Caretta caretta L.) rarely remate during nesting season

2019 ◽  
Vol 10 (1) ◽  
pp. 163-174
Author(s):  
Jacob A. Lasala ◽  
Colin Hughes ◽  
Jeanette Wyneken
Keyword(s):  
Sea Turtles ◽  
Caretta Caretta ◽  
Loggerhead Sea Turtles ◽  
Nesting Season

scholarly journals Plasma Vitellogenin in Free-Ranging Loggerhead Sea Turtles (Caretta caretta) of the Northwest Atlantic Ocean

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Kimberly Smelker ◽  
Lauren Smith ◽  
Michael Arendt ◽  
Jeffrey Schwenter ◽  
David Rostal ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Sea Turtles ◽  
Endocrine Disrupting Chemicals ◽  
Caretta Caretta ◽  
Reproductive Activity ◽  
Loggerhead Sea Turtles ◽  
Northwest Atlantic ◽  
Free Ranging ◽  
Vitellogenin Concentration ◽  
Nesting Season

Vitellogenin is the egg yolk precursor protein produced by oviparous vertebrates. As endogenous estrogen increases during early reproductive activity, hepatic production of vitellogenin is induced and is assumed to be complete in female sea turtles before the first nesting event. Until the present study, innate production of vitellogenin has not been described in free-ranging sea turtles. Our study describes circulating concentrations of vitellogenin in loggerhead sea turtles (Caretta caretta) from the Northwest Atlantic Ocean. We collected blood samples from juveniles and adults via in-water captures off the coast of the Southeast USA from May to August, and from nesting females in June and July at Hutchinson Island, Florida. All samples were analyzed using an in-house ELISA developed specifically to measureCaretta carettavitellogenin concentration. As expected, plasma vitellogenin declined in nesting turtles as the nesting season progressed, although it still remained relatively elevated at the end of the season. In addition, mean vitellogenin concentration in nesting turtles was 1,000 times greater than that measured in samples from in-water captures. Our results suggest that vitellogenesis may continue throughout the nesting season, albeit at a decreasing rate. Further, vitellogenin detected in turtles captured in-water may have resulted from exposure to endocrine disrupting chemicals.

scholarly journals Large-scale movement patterns of male loggerhead sea turtles (Caretta caretta) in Shark Bay, Australia

2012 ◽  
Vol 63 (11) ◽  
pp. 1108 ◽  
Author(s):  
Erica L. Olson ◽  
Anne K. Salomon ◽  
Aaron J. Wirsing ◽  
Michael R. Heithaus
Keyword(s):  
Breeding Season ◽  
Large Scale ◽  
Sea Turtles ◽  
Spatial Scales ◽  
Management Strategies ◽  
Caretta Caretta ◽  
Breeding Population ◽  
Loggerhead Sea Turtles ◽  
Shark Bay ◽  
Loggerhead Turtles

Large marine vertebrates are particularly susceptible to anthropogenic threats because they tend to be long-lived, late to mature and wide-ranging. Loggerhead sea turtles (Caretta caretta) are characterised by such life history traits and are listed as ‘Endangered’ by The World Conservation Union. Although juvenile movements and at-sea behaviour of adult females are relatively well studied, little is known about the movements of males and their subsequent exposure to threats. Shark Bay, Western Australia, is home to the largest breeding population of loggerhead turtles in Australia. We assessed the large-scale movements of nine adult male loggerhead turtles, with the goal of aiding conservation and management policies. During 7 months outside the breeding season, all nine turtles stayed within the Shark Bay World Heritage Area, with most showing fidelity to small coastal foraging areas. Several turtles, however, showed relatively large movements between core foraging areas. None of the four turtles that continued transmitting through the breeding season exhibited obvious movements towards nesting beaches, suggesting that mating may occur on foraging grounds or that males are not mating every year. Quantifying male loggerhead movements assists conservation planning by identifying biologically relevant spatial scales at which research and management strategies should be designed.

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.

Hatch rates of loggerhead turtles and physical characteristics of the beach at Fethiye, Turkey

2003 ◽  
Vol 83 (1) ◽  
pp. 231-232 ◽  
Author(s):  
Oğuz Türkozan ◽  
Çetin Ilgaz ◽  
Ertan Taşkavak ◽  
Adem Özdemir
Keyword(s):  
Environmental Factors ◽  
Moisture Content ◽  
Incubation Time ◽  
Hatching Success ◽  
Sea Turtles ◽  
Caretta Caretta ◽  
Physical Characteristics ◽  
Loggerhead Sea Turtles ◽  
Loggerhead Turtles ◽  
Nest Depth

The relation of moisture content, temperature, nest depth, incubation, distance from sea and vegetation to hatching success of loggerhead sea turtles, Caretta caretta, in Turkey was studied. Nineteen randomly selected clutches were examined. Moisture was found to be negatively correlated with distance from the sea (P<0·05) but positively correlated with temperature (P<0·01). Temperature was negatively correlated with incubation time. Hatching success was not correlated with any of the environmental factors examined.

Comparisons of Social Structure of Columbus Crabs Living on Loggerhead Sea Turtles and Inanimate Flotsam

1997 ◽  
Vol 77 (1) ◽  
pp. 185-194 ◽  
Author(s):  
Thomas Dellinger ◽  
John Davenport ◽  
Peter Wirtz
Keyword(s):  
Life History ◽  
Social Structure ◽  
Group Size ◽  
Sea Turtles ◽  
Caretta Caretta ◽  
Open Ocean ◽  
Life History Strategies ◽  
Loggerhead Sea Turtles ◽  
Loggerhead Turtles

Columbus crabs, Planes minutus (Crustacea: Brachyura) live in the open ocean attached to floating substrata including Sargassum, flotsam, and sea turtles. Eighty-two percent of 128 loggerhead turtles (Caretta caretta) checked, harboured a total of 172 crabs. Crabs inhabiting flotsam occurred in mixed sex groups of adults and juveniles, with a mean group size of 8.2 ±;11.8 (N=17). In contrast, crabs living on sea turtles around Madeira occur in smaller groups 1.6 ±0.5 (N=105) which are typically adult heterosexual pairs (61 out of 105). Crabs on turtles were bigger than on flotsam and a higher proportion of female crabs were brooding eggs. Columbus crabs exhibit different life history strategies depending on the substratum they inhabit.

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