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dc.contributor.advisorGatlin III, Delbert
dc.contributor.advisorMacKenzie, Duncan
dc.creatorGarner, Jeanne
dc.date.accessioned2012-07-16T15:58:47Z
dc.date.accessioned2012-07-16T20:29:21Z
dc.date.available2014-09-16T07:28:20Z
dc.date.created2012-05
dc.date.issued2012-07-16
dc.date.submittedMay 2012
dc.identifier.urihttps://hdl.handle.net/1969.1/ETD-TAMU-2012-05-11189
dc.description.abstractThe global population of leatherback sea turtles is decreasing worldwide, with extinction predicted for some populations within 15 years. The population of leatherbacks nesting at Sandy Point National Wildlife Refuge (SPNWR), St. Croix, USVI, displayed a significant population increase from 1982 2001 but has experienced a slowed recovery since then. To better understand the causes of this decline, a historical database of SPNWR nesting female data was utilized to investigate trends in reproductive indices. Since 2001, average remigration interval (RI) has increased significantly, while average number of clutches laid, hatch success, hatchling production, and the percentage of neophytes recruited annually have decreased. Annual remigrant numbers have been stable to increasing, suggesting that adult survivorship remains high. To assess whether maternallyderived factors may be influencing clutch production and low hatch success, blood samples were collected by saturation sampling during nesting. Circulating estradiol, testosterone, and progesterone were evaluated in conjunction with reproductive data. All hormones were highest at deposition of the first clutch and declined progressively with each consecutive clutch, as previously observed in other sea turtle species. Increased clutch production in remigrants was associated with higher estradiol levels compared to neophytes, presumably due to ovarian size and maturity. Contrary to observations in Pacific leatherbacks, progesterone decreased significantly with successive nests and total levels of estrogen were significantly lower, suggesting Atlantic leatherbacks may undergo a longer migration or spend more time in the feeding grounds prior to migrating. Linear Mixed Effect (LME) modeling was employed to determine whether hormone levels at nesting might serve as indicators of reproductive variables. Because models for all hormones were individual specific, a population model could not be developed that effectively utilized hormone levels at nesting to predict clutch size, hatch success, age or RI. However, number of clutches laid may potentially be predicted based on individually tailored estrogen models. Decreased recruitment (due to increased mortality of early life stages, altered sex ratios, or delayed age to sexual maturity), decreased productivity, and increased RI (possibly due to diminished foraging ground productivity) appear primarily responsible for current population trends which threaten the population's future.en
dc.format.mimetypeapplication/pdf
dc.language.isoen_US
dc.subjectLeatherbacken
dc.subjectsea turtleen
dc.subjectendocrinologyen
dc.subjectsteroid hormonesen
dc.subjectmodelingen
dc.subjectreproductiveen
dc.titleReproductive Endocrinology of Nesting Leatherback Sea Turtles in St. Croix, U.S. Virgin Islandsen
dc.typeThesisen
thesis.degree.departmentWildlife and Fisheries Sciencesen
thesis.degree.disciplineWildlife and Fisheries Sciencesen
thesis.degree.grantorTexas A&M Universityen
thesis.degree.nameDoctor of Philosophyen
thesis.degree.levelDoctoralen
dc.contributor.committeeMemberLandry, Andre
dc.contributor.committeeMemberWalzem, Rosemary
dc.type.genrethesisen
dc.type.materialtexten
local.embargo.terms2014-07-16


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