Climate change is threatening biodiversity, causing populations and species to adapt, or otherwise, become extinct. Sea turtles have survived dramatic climate changes in the past, however, due to a history of intense human exploitation, and the current anthropogenic threats, their current resilience may be jeopardized. The main pursuits of this thesis were to i) evaluate the resistance of green turtles to predicted climate change impacts, using a globally significant rookery, in Poilão, Guinea-Bissau, as a case study; and ii) assess key population parameters to inform the conservation management of this resource. As the work developed I additionally had the opportunity to study the dynamics of an emerging disease in a juvenile foraging aggregation from Puerto Rico, which contributed to a broader understanding of resilience in this species. Specifically, I investigate the nest site selection behaviour of green turtles, their nesting environment, and the outcomes for their offspring, at Poilão, and apply this information to infer on the resilience of this population under future scenarios of climate change. I explore the connectivity established by the dispersal of post-hatchlings from Poilão, followed by their recruitment to foraging grounds, to set the geographical context of this major population. Lastly, I model the dynamics of Fibropapillomatosis, which affects juvenile green turtles globally, and examine the potential for disease recovery. The green turtle rookery in Poilão shows some resilience to expected climate change impacts. This significant population likely contributes to all juvenile foraging aggregations along the west coast of Africa, and to some extent to those in South America. Currently, green turtles are capable of recovery from Fibropapillomatosis, however, the incidence of disease may be enhanced by climate change.

Sea turtle hatchlings emerge from their nest and quickly crawl to the surf. During the crawl, hatchlings may encounter threats, biotic and abiotic, which can affect their ability to successfully reach the surf. The impact of these threats on hatchling survival during that crawl is largely undocumented. Current methods used to estimate cohort recruitment rely heavily on nest inventory data. This method, however, does not account for post-emergent hatchling mortality that occurs during the crawl. During the 2017-2018 nesting seasons, I quantified the fates of 1,379 loggerhead (Caretta caretta) hatchlings from 26 nest emergences during their crawl from the nest to the surf on the east and west coasts of Florida. I documented hatchling fates at 5 Florida nesting beaches: Wabasso, Boca Raton, Keewaydin Island, Naples, and Anna Maria Island. Overall, 6.5% of all emergent hatchlings died during the crawl from the nests to the surf. Ghost crabs, night herons, foxes, and coyotes killed hatchlings and photopollution and barriers on the beach (both abiotic threats) caused hatchling mortality. Anthropogenic (abiotic) threats accounted for more mortality than did predators. In order to assess how beach urbanization impacts hatchling mortality, I categorized each study site as urban (Wabasso and Naples), intermediate (Anna Maria Island and Boca Raton), or natural (Keewaydin Island) based on the relative levels of shoreline development and human activity at each beach. Sites with intermediate levels of urbanization accounted for greater levels of hatchling mortality than at other beaches due to the absolutely larger numbers of hatchlings lost to a disorientation event and to a beach barrier. Given the small numbers of emergences, at all sites, only a small proportion of the hatchlings mortalities (e.g., between 3 and 12 percent), site type could not be rigorously used as a discriminator. My results provide a better understanding of how specific environmental threats contribute to hatchling mortality. While nest-to-surf mortality is relatively low, its cumulative costs add up to several hundreds of thousands of hatchlings. Armed with this information, nesting beach managers can assess risks and focus their efforts to implement the most effective management practices to minimize losses of this imperiled species. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection

Climate change will expose sea turtle nests to higher temperatures and more storms; both may negatively impact sea turtle nest success. In this study, unhatched eggs were collected from the Boca Raton, Florida beach and developmental stage at embryonic death determined. Elevated nest temperatures increased embryonic mortality, and the most significant relationship was between mortality and the percent of time embryos were exposed to temperatures above 34°C. Loggerhead turtles exhibited higher rates of mortality compared to green turtles at temperatures above 34°C. Only loggerhead nests were exposed to inundation, but embryonic mortality did not differ from noninundated nests. Beach profiles across the nesting season were also determined. A major storm altered the beach more in areas of coastal development; however, this was impacted by a nourishment project and the presence of a structured inlet. Future management strategies may need to protect sea turtle nests from extended periods at elevated temperatures. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection

No description available.

Sea Turtles are long-lived marine reptiles that have existed for more than 150,000 years. All seven turtle species extant today are characterised as endangered by the World Conservation Union Red List of Threatened Species. This PhD thesis investigates aspects of endocrinology and toxicology in green (Chelonia mydas) (Peninsular Malaysia) and flatback (Natator depressus) (Curtis Island, Queensland, Australia) turtles. This thesis aimed to identify if toxicants have an affect on reproduction and development in marine turtles. A high affinity steroid binding protein showing an affinity for testosterone and oestradiol was identified and described in nesting C. mydas and the thermal profile of sex steroid binding proteins in C. mydas was studied. This is the first study that has investigated sex steroid binding proteins in marine turtles. A sex steroid binding protein was also observed in male and female hatchling C. mydas and the effect of temperature on sex steroid binding proteins was investigated. This new, minor-invasive method of sex identification shows that different sex steroid binding proteins could reflect different hormonal patterns in female and male hatchling C. mydas. The steroid and metabolites profiles in nesting C. mydas (Peninsular Malaysia) and N. depressus (Curtis Island, Queensland) were established. Progesterone levels were the highest followed by testosterone, oestrone and dihydrotestosterone levels. The significant role of oestrone in nesting sea turtles was verified. The elevated concentrations of corticosterone, thyroxine, glucose and triglyceride indicated high metabolic demands placed upon C. mydas and N. depressus during nesting activities. The metabolite profiles and hormone concentrations were investigated to determine whether there was any relationship between hormonal changes during nesting activities in C. mydas and N. depressus. A methodology to measure heavy metal concentrations in the blood and eggs of N. depressus was developed. Moreover, this was the first time that tin compound derivatives have been identified in marine turtles in Australia. A complex heavy metal profile was identified in eggs. It is suggested that eggs may be an important, practical and reliable indicator of environmental contamination in nesting marine turtles. Pesticides were measured in the blood and eggs of N. depressus. Organochlorine and polychlorinated biphenyl concentrations were measured in the blood in N. depressus. Traces of OCs and PCBs were detected in eggs of N. depressus. Furthermore, the effects of heavy metals in developing C. mydas of both sexes are presented. During development, it was investigated whether heavy metal concentrations were affected by age, gender or the different clutch in C. mydas. The effect of a variety of toxicants (i.e. pesticides and heavy metals) on the sex steroid binding protein properties was investigated in nesting C. mydas. This important study identifies mechanisms by which toxicants may exert a physiological effect upon sex steroids (i.e. testosterone and oestradiol) in nesting turtles. The toxicants were studied at a wide range of concentrations. Some toxicants were shown to weaken or abolish the association of the testosterone and/or oestradiol binding proteins in nesting C. mydas. Correlations were observed between heavy metal concentrations found in blood and eggs and steroid and metabolite levels in nesting N. depressus. Zinc which was previously measured in the blood was positively correlated with testosterone concentrations in nesting N. depressus. Chromium which was found in eggs was negatively correlated corticosterone concentrations. Manganese was the only heavy metal (measured in eggs) which was negatively correlated with progesterone and positively correlated with triglyceride concentrations in nesting N. depressus. Finally, a quantified histological method was developed to determine the sex in C. mydas hatchlings by investigating specific histological criteria. A number of “undetermined sex” hatchlings were verified and it is hypothesised that abnormal reproductive development is related to the presence of environmental contaminants previously found in the studied C. mydas population of Peninsular Malaysia.

Thesis (Ph.D.) - James Cook University, 2002. / Bibliography: leaves 222-244.

As climate change threatens with sea-level rise and more storms, increased erosion could increase the need for beach nourishment. Alterations to sand characteristics may result in changes to the sea turtle nest microenvironment, impacting the temperature and oxygen levels which may affect hatchling performance. In this study, leatherback, loggerhead, and green nests were sampled from two sites with different sand characteristics in Juno Beach, Florida, USA. Gas exchange was higher in green turtle nests with a greater mixture of sediment. Darker sediment elevated nest temperatures. Finer sediment and a greater mixture of sediment in leatherback nests elevated the nest temperatures; conversely finer sediment, and a greater mixture of sediment decreased loggerhead and green nest temperatures. Elevated nest temperatures reduced leatherback, loggerhead, and green turtle hatchling performance. Understanding the relationships between beach composition, nest environment, and hatchling performance will aid management decisions essential to sea turtle conservation. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection

No description available.

During the summers of 1988 and 1989, nests of 528 loggerhead sea turtles (Caretta caretta), 27 green sea turtles (Chelonia mydas), and 1 leatherback sea turtle (Dermochelys coriacea) were monitored on Wabasso Beach in Indian River County, Florida. Two hundred and forty four of the loggerhead and 2 of the green sea turtle nests were marked during night surveys as the females laid their clutches, permitting exact clutch counts and carapace measurements on the nesting females. Each marked nest was inspected daily for signs of disturbance and hatching. After incubation (70 days), study nests were excavated and inventoried to determine hatchling emergence success. Parametric multiple regressions, nonparametric multiple regressions, and logistic regressions were used to determine the effects of several measured variables on clutch sizes and incubation times; and nesting, hatchling emergence success, and predation. Excluding the last 2 weeks of the nesting season, nesting was positively correlated with ocean temperatures (P< 0.05), but not with human beach-side development (P> 0.05). Nesting loggerheads on the study area had an average carapace length of 89.8 cm (S.E.=0.31), and a mean clutch size of 112 eggs (S.E.=1.07). Clutches required an average of 53.9 days (S.E.=0.21) to incubate during 1988, with a hatchling emergence success of 57%. During 1989, the mean incubation time and hatchling emergence success was 51.5 days (S.E.=0.21) and 44%, respectively. Over the 2 study years, the average green turtle nest had 118 eggs, took 54.6 days to incubate, and had a hatchling emergence success of 40%. During 1988, 4.6% of the loggerhead nests were lost to beach erosion or alteration (deposition of sand on nests by the surf). This loss was 22% during 1989 for loggerheads, and 30% over both years for green turtles. The difference in loggerhead losses over the 2 years was due to 2 late-season hurricanes which affected the area during 1989. Predation on loggerhead nests was 16% and 8% during 1988 and 1989, respectively. In both years, predation was positively correlated with human beach-side development (P<0.05); during 1989, predation also was positively correlated with distance of the nest from the beach dune (P< 0.05). Clutch size and carapace size of nesting females were positively correlated (P< 0.05). Incubation time was negatively correlated with egg laying date, and hatchling emergence success was strongly affected by the late summer storms of 1989. The study area produced an estimated 70,469 loggerhead sea turtle hatchlings per year (8,808 hatchlings/km), and 535 green sea turtle hatchlings per year (66 hatchlings/km). The number of loggerhead sea turtle hatchlings produced per nest was adversely affected by beach-side development. / Master of Science

Two species of sea turtle, loggerheads (Caretta caretta) and leatherbacks (Dermochelys coriacea) are caught frequently as bycatch in longline fisheries. These fisheries use hooks baited with fish or squid. Yet, leatherbacks feed on gelatinous prey while loggerheads are carnivores. I investigated the responses of these two species to bait odors in controlled laboratory experiments to better understand their feeding behavior and why they interact with longlines. Both species initiated feeding behavior in the presence of squid bait odors and just C. caretta showed feeding behavior with sardine odors; neither responded to mackerel odors. The turtles are hooked differently on longlines. Loggerheads are usually hooked in the mouth while leatherbacks are usually hooked in the shoulder or flippers. Comparisons of prey attack behavior and accuracy in apprehending a stimulus in the presence of waterborne food odors identified speciesspecific differences that may predispose the turtles to particular kinds of hooking. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection