Female loggerhead sea turtles (
            Caretta caretta
            L.) rarely remate during 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.

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Note on the unique physiologic state of loggerhead sea turtles (Caretta caretta) during nesting season as evidenced by a suite of health variables

Marine Biology ◽

10.1007/s00227-018-3331-1 ◽

2018 ◽

Vol 165 (4) ◽

Cited By ~ 3

Author(s):

Justin R. Perrault ◽

Nicole I. Stacy

Keyword(s):

Sea Turtles ◽

Caretta Caretta ◽

Loggerhead Sea Turtles ◽

Physiologic State ◽

Nesting Season

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

Canadian Journal of Zoology ◽

10.1139/z92-080 ◽

1992 ◽

Vol 70 (3) ◽

pp. 530-538 ◽

Cited By ~ 71

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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Sex ratio of loggerhead sea turtles hatching on a Florida beach

Canadian Journal of Zoology ◽

10.1139/z89-358 ◽

1989 ◽

Vol 67 (10) ◽

pp. 2533-2539 ◽

Cited By ~ 40

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.

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