Nest predation can significantly reduce hatchling recruitment in sea turtle populations. This study uses 20 years of data from Canaveral National Seashore, Florida, which has pristine and altered beaches. Chi-square tests were used to determine if secondary predation events were related to the nest's primary depredation event. To determine if human beach use and nest predation are spatially or temporally linked, we ranked human beach use and examined predation frequency across all screened and marked nests (n=40,441). Lastly, I quantified nest predation risk spatially and temporally. I found that primary predation increases the chance of a nest suffering subsequent predation. Primary and multiple predation events occurred with greater frequency in limited use areas and with lowest frequency in moderate use areas. Predation risk decreased by an average of 29.5% from 2000-2008. Nests deposited midseason were 9.8% more likely to be predated than nests deposited early or late. / by Rachel Welicky. / Thesis (M.S.)--Florida Atlantic University, 2010. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2010. Mode of access: World Wide Web.

The photopollution of beaches caused by artificial light sources can interfere with sea turtle hatchlings' ability to orient properly towards the sea. Exhaustion due to extended disorientation crawling may then increase hatchling mortality. This study evaluated the energetic consequences of long-distance crawls in green and loggerhead sea turtle hatchlings. Turtles crawled for 200 m or 500 m on a treadmill, followed by a 30 minute evaluation of swim performance. Metabolic activity was quantified via measures of blood glucose, blood lactate, and oxygen consumption. No significant changes in metabolism resulted from long-distance crawling activity in loggerheads ; however, loggerheads rested for extended periods of time during the crawl trials, often unresponsive to stimuli. This behavior implies that loggerhead hatchlings would be vulnerable to predation or temperature stress due to exhaustion from extended periods of crawling. Further data is required to draw any significant conclusions about long-term disorientatin crawling in green hatchlings. / by Sean Williams. / Thesis (M.S.)--Florida Atlantic University, 2012. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.

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

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

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

South Florida's loggerhead (Caretta caretta), green (Chelonia mydas) and leatherback (Dermochelys coriacea) sea turtles hatchling have environmentally determined sex. The in situ nest mean hatchling sex ratios (SR) were highly female-biased : loggerhead F=0.89) and green turtle F=0.81; leatherback's SR was nearly balanced (0.55F). Nest temperatures and SRs differed between leatherbacks and loggerhead and green turtles. The latter two did not differ. The loggerhead response parameters were estimated within biological limitations by both 50-65% of incubation and mean middle 1/3 temperature. The maximum middle 1/3 temperature was the best-fit predictor for green turtles. No best-fit sex ratio-temperature response could be identified for leatherbacks. Clutches incubating under natural conditions can vary greatly in SR ; TRT differences may account for differences among species' sex ratios. / by Micah Marie Rogers. / Thesis (M.S.)--Florida Atlantic University, 2013. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.

Coastal habitats are highly dynamic and vulnerable to landscape-level disturbances such as storms and restoration projects. Along the east coast of Florida these areas are particularly valuable as they provide significant nesting habitat for two sea turtle species, the threatened loggerhead (Caretta caretta) and the endangered green turtle (Chelonia mydas). This coast was heavily impacted by three major hurricanes in 2004 and in some areas by large restoration projects in 2005. Recent remote sensing methods allow for broad evaluation of the shoreline and thus the ability to assess sea turtle nesting habitat at a landscape scale. I collected nesting data for southern Brevard County, Florida from 1989 – 2005 and for Canaveral National Seashore, Florida from 1995 – 2005. I used LiDAR (Light Detection and Ranging) and IfSAR (Interferometric Synthetic Aperture Radar) remote sensing to map sea turtle nesting habitat in both areas following the 2004 hurricanes and any subsequent restoration. Canaveral National Seashore underwent no restoration while southern Brevard County received extensive restoration. Topographic variables (e.g., total sand volume, width, and slope) derived from the remote sensing data were compared across three time periods (pre-hurricane, posthurricane, and recovery period) and I compared nesting success data from 2004 to 2005. I built regression models for 2004 and 2005 to determine which topographic features influenced loggerhead and green turtle nesting the most. Green turtle nesting success declined from 2004 to 2005 only in highly restored areas while loggerhead nesting sucess declined throughout. Hurricanes caused a reduction in most of the topographic variables and restoration predominantly impacted aspects of the beach profile (e.g. slope and width). Loggerheads responded to profile characteristics (e.g. upper and lower iii beach slopes) though green turtles showed no consistent response to topography. The results indicate that both loggerheads and green turtles are sensitive to beach restoration, although loggerhead nesting is more influenced by beach morphology and green turtle nesting may be influenced more by other dune features such as vegetation cover.

Understanding the movements and behavior of hawksbi1l sea turtles is vital to their protection, but existing data on these subjects are insufficient. The objectives of this study were 1) to monitor internesting movements and surfacing behavior of hawksbill sea turtles nesting at Buck Island Reef National Monument, St. Croix, and 2) to describe post-nesting movements of Buck Island hawksbills. Surfacing behavior and presence or absence of tagged turtles W(> :-t' monitored 24 hr a day by a computerized tracking system using pulse-coded transmitters. Internesting and post-nesting movements were tracked using satellite transmitters on the ARGOS system. No clear trends were apparent in total time spent at the surface. either during an internesting interval or when comparing day and nigh~ behavior; behavior was turtle and interval-specific (n=3). The number of times a turtle surfaced over an internesting interval also varied among turtles, but all turtles surfaced more frequently at the end of an internesting interval (P < 0.05). No differences were found in the number of times turtles surfaced during the day versus night, with the exception of one turtle which surfaced more frequently during the daytime. Comparisons of day and nighttime activity among turtles revealed that surfacing behavior was similar among the turtles studied with the exception of one turtle that spent significantly more time at the surface than the other turtles during both day and night. Internesting movements were found to be extensive for 2 of 3 turtles tracked t with turtles moving from 197 km to 845 km from Buck Island. The third turtle remained within 1 km of Buck Island. Tagged turtles left the Buck Island vicinity immediately after nesting for the season. Two turtles tracked with pulse-coded transmitters through the end of their nesting effort were last heard less than 24 hr after laying their last nest. Satellite tagged turtle T3, tracked for 10 months, traveled between the British Virgin Islands and Puerto Rico for 3 months, then became resident off the southern coasts of St. Thomas and St. John, USVI. Turtle T3 left this area occasionally on short-duration excursions, but always returned. Satellite tagged turtle T8, tracked for 1.5 months, moved to Puerto Rico immediately after completing nesting for the season, and was subsequently located off the coast of the Dominican Republic t St. Vincent (The Grenadines), and the northern coast of Venezuela. A third turtle (TIl) was located only once after laying her last nest; at the island of Anegada, BVI. Frequent failure to receive locations from satellite transmitters that were known to be attached and functional suggests that turtles may not stay at the surface long enough for transmissions to reach the ARGOS satellites. / Master of Science

Sex determination in leatherback sea turtles is directed primarily by the temperatures a clutch experiences during the middle third of development. Warmer temperatures tend to produce females will cooler temperatures yield males. Nest temperatures can vary spatially and temporally. During the 2010 and 2011 nesting seasons, this study estimated the hatchling sex ratio of leatherback sea turtles on Sandy Point National Wildlife Refuge (SPNWR), St. Croix, U.S. Virgin Islands. I measured sand temperatures from May- August and across the spatial range of leatherback nesting habitat. I spatially interpolated those temperatures to create maps that predicted temperatures for all nests incubating on SPWNR. Nest temperatures were also directly measured and compared with predicted nest temperatures to validate the prediction model. Sexes of dead-in-nest hatchlings and full term embryos were used to confirm the sex-temperature response. The model showed that microclimatic variation likely impacts the production of both sexes on SPNWR. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2013.