Following nest emergence, sea turtle hatchling dispersal can be disrupted by artificial light or skyglow from urban areas. Mis- or disorientation increases exposure to predation, thermal stress, and dehydration, could consume valuable energy, and thus influence the likelihood of survival. This study utilized laboratory simulations of extended crawl distances and field observations to investigate the energy cost of disorientation crawling on loggerhead (Caretta caretta) and green (Chelonia mydas) sea turtle hatchlings and the impact on the subsequent swim frenzy. Extended crawls increased oxygen consumption, decreased plasma glucose, and reduced green hatchling swim performance following a 200m crawl. Surprisingly, plasma lactate concentrations did not increase with crawl distance, likely due to frequent rest periods that would, however, increase time on the beach and thus exposure to predators. This research may provide managers with physiological data to determine best practices for sea turtle conservation and adds to the biological knowledge of these animals. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2016. / FAU Electronic Theses and Dissertations Collection

The dinoflagellate Karenia brevis is one organism responsible for harmful algal blooms (HABs) that severely impact marine life. K. brevis produces a suite of neurotoxins referred to as brevetoxins (PbTx) which bind to voltage-gated sodium channels (VGSCs) in excitable tissues, affecting cellular permeability leading to a suite of symptoms and potentially cell death. Brevetoxicosis is difficult to treat in sea turtles as the physiological impacts have not been investigated and the magnitude and duration of brevetoxin exposure are generally unknown. Due to their threatened and endangered status, experimental exposures cannot be performed to determine the fate of brevetoxin in sea turtle tissues, making it difficult to design appropriate treatments. The freshwater turtle, Trachemys scripta, was utilized as a model for brevetoxin exposure in turtles. Turtles were exposed to intratracheal instillation (10.53μg/kg) or oral dosing (33.48μg/kg) of PbTx-3 3x weekly over a period of 2-4 weeks. Tissues and fluids were collected for ELISA to determine PbTx-3 uptake and distribution, routes of excretion and rates of clearance (1h-1wk post-exposure). Tissues were also preserved for histopathology. Primary turtle neuronal cell cultures were exposed to PbTx-3 in the presence and absence of various agonists and antagonists to determine brevetoxin’s mode of action. PbTx-3 was widely distributed in all tissues and fluids following both intratracheal and oral exposures, but was largely cleared from the system within 24 hours; PbTx-3 moved into the bile and feces over 48h post exposure indicating that this is the main route of excretion. While exposed animals showed clear behavioral symptoms of toxicity including muscle twitching, swimming in circles, and ataxia, there was no evident tissue pathology. Despite the evident behavioral effects, turtle neurons are surprisingly resistant to PbTx-3, with an EC50 significantly higher than is seen in mammalian neurons. While PbTx-3 exposure resulted in significant Ca2+ influx, various antagonists prevented Ca2+ influx when added with PbTx-3 confirming the mechanism of action through VGSCs. Upregulation of Hsp72 in the turtle brain could be enhancing cell survival. Based on results, intralipid treatment post PbTx-3 exposure rapidly decreases symptoms and proves to be a suitable treatment for toxin exposure. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection

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.