Thesis (Ph. D.)--College of William and Mary. / Vita. Includes bibliographical references.

Thesis (Ph.D.)--Drexel University, 2007. / Includes abstract and vita. Includes bibliographical references (leaves 104-115).

Thesis (M.S.)--University of Alabama at Birmingham, 2008. / Description based on contents viewed Feb. 15, 2009; title from PDF t.p. Includes bibliographical references.

Thesis (Ph. D.)--Duke University, 2007. / Includes bibliographical references.

Thesis (M.Sc.)--Acadia University, 2000. / Includes bibliographical references (leaves 66-71). Also available on the Internet via the World Wide Web.

Hatchling marine turtles exhibit a positive phototaxis by crawling toward the lowest and brightest horizon when they emerge from nests on the beach at night, which should lead them to the ocean (“seafinding”). Previous research with cheloniid (loggerhead and green turtle) hatchlings demonstrated that the perceptual spectral sensitivities are well below the light available on the beach regardless of lunar phase. The goal of this research was to determine the perceptual spectral sensitivities of leatherback hatchlings, the most distantly related of all extant sea turtle species. This study revealed that, like cheloniids, leatherbacks are most sensitive to shorter wavelengths (< 500 nm). However, leatherbacks were 10 – 100x less sensitive than cheloniids at all tested wavelengths. This difference in sensitivity corresponds with increased crawl duration and circling behavior under new moon conditions when light levels are lowest and the difference in radiance between the landward and seaward direction is small. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection

The leatherback sea turtle (Dermochelys coriacea) is facing global declines; however, the Florida stock is generally increasing. Various studies have identified threats to sea turtles, but there is a need to quantify population-level threats. I used external examination and blood analyses of leatherbacks nesting on northern Palm Beach County, Florida beaches to understand the impact(s) that physical injuries have on this population. Notable injuries were present on 118 of 167 (70.7%) turtles. Fisheries injuries were more prevalent than other anthropogenic injuries; however, there was a higher overall prevalence of natural injuries. There were no notable findings from my blood analyses. My results suggest that while natural injuries are more common than anthropogenic injuries in the nesting population of Florida leatherbacks, anthropogenic injuries are more likely to result in severe traumatic wounds. Future investigation of overlap in leatherback migratory routes and foraging grounds with various threats could further protect this species. / Includes bibliography. / Thesis (MS)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection

The migratory behavior of North Atlantic leatherback turtles (Dermochelys coriacea) has been documented in the Wider Caribbean, but the migratory movements of leatherbacks nesting in South Florida are relatively understudied. Our knowledge of their migrations is currently limited to ten nesting females tracked from the east coast of Florida that either moved north to the Northern Atlantic or east to the coast of Western Africa. These results bring to light the need for further investigation and larger sample sizes to identify and determine the relative importance of the different foraging areas for the leatherbacks nesting in South Florida. Here, I analyzed stable carbon (δ13C) and stable nitrogen (δ15N) values in whole blood and skin of leatherbacks nesting in South Florida between 2014 and 2017 to estimate the putative foraging origins of these nesters prior to coming to South Florida to nest. This study provides some of the first stable isotope inferences and insights into the variable pre-nesting foraging habitat locations of Florida’s leatherback population. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

The 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.

The reproductive success of leatherback turtles (Dermochelys coriacea) is typically the lowest of the seven sea turtle species. Why this vital rate is decreased has remained unanswered for nearly a century. Recently, detailed postmortem examination of leatherback hatchlings identified muscular pathologies that suggested possible selenium deficiency. High bodily burdens of mercury compounds are associated with selenium depletion. Selenium is a necessary detoxifying nutrient that itself can be toxic at elevated concentrations. Mercury compounds are toxicants with no known biological function. High bodily concentrations of mercury can be detrimental to marine organismal health, reproduction and survival, both directly and indirectly through inducing selenium depletion. The goals of this dissertation are to evaluate several related hypotheses to explain low leatherback nest success. ... Because leatherbacks take in high volumes of prey, high tissue concentrations of mercury and selenium can result. This study provides the first evidence that chemical contaminants may explain low reproductive success in leatherback sea turtles. / by Justin R. Perrault. / Thesis (Ph.D.)--Florida Atlantic University, 2013. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.