A variety of anthropomorphic and environmental stresses are threatening the existence of all seven species of sea turtles. There is growing evidence that alterations in surface waters and sediment temperatures are negatively impacting reproductive success of loggerhead sea turtles (Caretta caretta). Fluctuations in water temperature associated with localized climate oscillations heavily alter the food web dynamics of the ocean. Feeding conditions are expected to be a critical factor in determining body mass and productivity for breeding seasons. An increase in regional temperatures could lead to prolonged reduction in food sources, as well as reduced nesting and recruitment. Loggerhead sea turtle nesting data from 1995-2011 werre compared with the average yearly North Atlantic Oscillation (NAO) and Atlantic Multidecadal Oscillation (AMO) which are important climatic events impacting the SST in the Atlantic Ocean. Because El Niño Southern Oscillation (ENSO) is a global event, it was proposed that turtles in the Atlantic may follow a similar trend. ENSO was quantified using Oceanic Nino Index (ONI). Analysis of loggerhead sea turtle nest frequencies from the years 1995-2011 in comparison to seasonal climate changes showed a significant inverse relationship between the detrended loggerhead nests and average yearly NAO when lagged two years, suggesting loggerheads may spend years prior breeding obtaining optimum body mass to increase successful reproduction. The detrended nesting data showed a tendency toward higher occurrence of nests during La Niña years while nest frequencies decreased during El Niño year; when the yearly detrended loggerhead nesting data was compared with the average yearly ONI; showing a significant inverse relationship without a lag. This may also suggest a relationship between changes of productivity of the ocean influenced by smaller scale climate changes and loggerhead nest frequencies.

Loggerhead and leatherback sea turtles nest on the beaches of the north-eastern portion of Kwazulu-Natal within the iSimangaliso Wetland Park. Loggerheads place ~60 percent of all nests within an 8 km stretch of beach, whereas leatherbacks tend to space their nests more evenly along the entire length of the monitoring area. The study aimed to determine nest site fidelity of loggerheads and leatherbacks (using four decades of nesting data housed by Ezemvelo KZN Wildlife) and the factors that influence nest site selection of both species within the 56 km of turtle monitoring area (32N to 100S) and the 5 km area of high-density loggerhead nesting (0N to 12N). The effectiveness of nest site selection was then determined through the hatching success of loggerheads over the 5km area (0N to 12N). Results showed that loggerheads show a high degree of nest site fidelity (~3 km) with nest site fidelity of individuals increasing over subsequent seasons of nesting, as well as these individuals using the same stretches of beach for nesting (the most popular area being 1N to 4N for repeat nesters). Leatherbacks displayed nest site fidelity of ~9 km and this did not increase over successive seasons of nesting. In terms of nest site selection, loggerheads and leatherbacks both avoided areas where low shore rock was present, whereas both species preferred nesting on beaches of intermediate morphodynamic state. Leatherback nesting was significantly higher in areas with wider surf zones. Both species were able to surpass the high water mark when nesting as nests below this point would be almost certainly doomed. Hatching success of loggerheads was comparative to high (83 %) relative to other studies, however, nest success varied across the beach from beacon 1N to 12N. Areas where highest nest success was observed were not areas of highest nest density presumably due to artificial lighting. Results from this study increase our understanding of the evolutionary biology of loggerhead and leatherback turtles in South Africa and the effectiveness of loggerhead nest site selection through hatching success.

<div>Understanding what sea turtles are feeding on and where they are feeding is key to understand their overall biology and will aid in understanding what type of management actions are necessary in order to conserve and protect these endangered species. Here I set out to (1) examine the population-level isotopic profiles of three sea turtle species in the Eastern Tropical Pacific; (2) determine differences in their foraging strategies; (3) attempt to gain insights about their pre-nesting origins; and (4) determine whether body size would influence the isotopic values of an individual turtle.</div><div>Stable isotope analysis (δ¹³C and δ¹⁵N values) was conducted on tissue samples from 52 sea turtles nesting on Playa Cabuyal, Costa Rica; 28 Pacific green (<i>Chelonia mydas</i>), 20 olive ridley (<i>Lepidochelys olivacea</i>), and 4 leatherback (<i>Dermochelys coriacea</i>). Nine satellite transmitters were also deployed on a separate population of post-nesting Pacific green turtles from Playa Cabuyal.</div><div>Based on isotopic profiles, green turtles in the Eastern Tropical Pacific were found to be feeding at a higher trophic level when compared to green turtles in other regions and this was supported by their increased δ¹⁵N values (16 ± 0.8 ‰). Rather than shifting to herbivory as adults, green turtles foraging in the eastern Pacific are potentially remaining omnivorous. Tracking data further confirmed that green turtles are coastal migrators and are probably inhabiting areas with high δ¹⁵N values within this region. Olive ridley turtles are exhibiting similar behavior to olive ridley turtles elsewhere due to minimal variance in their isotopic profiles (δ¹³C = -15.1 ± 0.7 ‰, δ¹⁵N =14.2 ± 0.8 ‰) and their known nomadic behavior. Although a small sample size, leatherback turtles showed a shift in their foraging habitats suggesting they are also feeding inshore in addition to their pelagic behavior due to their increased δ¹³C values (-15.5 ± 0.4 ‰). Further, as body size increased in olive ridley’s, the δ¹⁵N values significantly decreased suggesting that larger turtles prefer deeper pelagic waters with less enriched N isotope concentrations. However, in order to rule out possible external factors influencing this relationship, knowing where the turtle is originating from is crucial. This project provides data for developing isoscapes in the Eastern Tropical Pacific to aid in understanding the spatial distribution of sea turtles and their foraging grounds and the impact that foraging area may have on overall biology of these species. This information can be used to prioritize high use foraging habitats and determine the most effective management practices for protecting these species and the prey and habitat on which they rely.</div>

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The younger life history stages of marine turtles (eggs, hatchlings) often fail to survive. To compensate, sea turtles nest several times/season and produce large clutches of eggs. The hawksbill produces the largest clutches (150 eggs) and the smallest hatchlings of any marine turtle. My study, done at Jumby Bay in Antigua, West Indies, was designed to determine whether they did so to compensate for loss in the nest, hatchling loss in the water, or both factors. I found that most of the eggs (79 %) survived to become hatchlings that left the nest and entered the sea. However, 88 % of the hatchlings swimming offshore were taken by predators within minutes after they began their migration. These results suggest that at Jumby Bay, large clutch size is favored in hawksbills because of predation pressures on the hatchlings. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2013.

A interação das tartarugas marinhas da espécie Caretta caretta e Dermochelys coriacea com o espinhel pelágico é um dos fatores que mais causa a mortalidade destes animais no oceano. Estudos com o intuito de quantificar essa interação, bem como os fatores que influenciam a mesma, são crescentes, para os quais é necessário conhecer a distribuição dos animais, e correlacioná-la com variáveis ambientais e operacionais da pesca. O presente estudo visa avaliar e quantificar os padrões espaço-temporais das capturas acidentais das tartarugas marinhas C. caretta e D. coriacea na região Sudeste/Sul do Brasil, com base em dados coletados pelo Projeto TAMAR ICMBio, entre 2003 e 2010, a partir de um programa de observadores à bordo da frota comercial com espinhel pelágico, assim como correlacioná-los com variáveis ambientais, biológicas e operacionais. Para tal, foram utilizados métodos estatísticos, como os Modelos Aditivos Generalizados para Posição, Escala e Forma (GAMLSS). Foram verificadas variações interanuais e sazonais, com destaque para maiores capturas por unidade de esforço (CPUE) no outono. A temperatura superficial do mar foi a variável abiótica de maior correlação com a CPUE de C. caretta, sendo tipo de isca, a variável operacional mais significativa. Para D. coriacea, profundidade e longitude foram os fatores que melhor explicam a CPUE. Padrões de distribuição ontogenética e áreas prioritárias de conservação para essas populações são discutidas, assim como os efeitos potenciais do aquecimento do oceano. O presente estudo deve contribuir para a definição de políticas de conservação marinha e no contexto da abordagem ecossistêmica para a pesca / The interaction between the sea turtles Caretta caretta and Dermochelys coriacea with pelagic longline is one of the factors that cause mortality of these animals in the ocean. Studies in order to quantify this interaction, as well as the factors that influence it, are increasing, focusing mostly on the turtles distribution, and how it correlates with environmental and fishing operational variables. Present study aims to evaluate and quantify the spatio-temporal patterns of the sea turtles C. caretta and D. coriacea bycatch off Southeast/South Brazil, based on data collected by Project TAMAR - ICMBio between 2003 and 2010, from an observer program on-board the commercial pelagic longline fleet, as well as to correlate them with environmental, biological and operational variables,. Statistical methods such as Generalized Additive Models for Location, Scale and Shape (GAMLSS) were applied. Interannual and seasonal variations were observed, with a higher catch per unit effort (CPUE) during fall. The sea surface temperature was the abiotic variable that most correlated with CPUE of C. caretta, being the type of bait the most significant operational variable. For D. coriacea, depth and longitude were the factors that better explained the CPUE. Ontogenetic distribution patterns and priority areas for the species conservation are discussed, as well as the potential effects of ocean warming. This study should contribute to the definition of conservation policies as well as to the ecosystem approach to fisheries context

Les tortues marines, espèces emblématiques des écosystèmes marins, sont de plus en plus menacées par les effets directs et indirects des activités humaines. Leur cycle de vie est complexe, partagé entre divers habitats, souvent très éloignés les uns des autres. Leur conservation nécessite donc d'identifier les habitats occupés à chaque stade de vie et les routes migratoires empruntées entre ces différents habitats. Si l'écologie spatiale des tortues adultes est relativement bien connue, notamment grâce au suivi par satellite, il n'en va pas de même pour les juvéniles qui se développent plusieurs années en milieu pélagique sans pouvoir être suivis. Dans ce contexte, les simulations numériques constituent un outil adapté pour explorer la dispersion des tortues juvéniles à partir de leurs plages de naissance. Jusqu'à présent il a le plus souvent été supposé dans ces simulations que les juvéniles dérivaient passivement avec les courants marins. Dans ce travail de thèse nous présentons STAMM (Sea Turtle Active Movement Model), un nouveau modèle de dispersion active des tortues juvéniles qui s'attache à dépasser l'hypothèse initiale d'une dérive purement passive. Dans STAMM, les juvéniles simulés se déplacent sous l'influence de la circulation océanique et d'une nage motivée par la recherche d'habitats favorables. Ce modèle est appliqué ici à l'étude de la dispersion des juvéniles de trois populations de tortues marines : les tortues luths (Dermochelys coriacea) du Pacifique Ouest et de l'Atlantique Nord-Ouest puis les tortues caouannes (Caretta caretta) de l'ouest de l'océan Indien. Nos résultats montrent que, même si la circulation océanique détermine, à grande échelle, les zones de dispersion, la prise en compte des mouvements motivés par l'habitat augmente considérablement le réalisme des simulations et impacte profondément la distribution spatiale et temporelle des individus simulés à l'intérieur de leur zone de dispersion. Les mouvements motivés par l'habitat induisent notamment des migrations saisonnières en latitude qui réduisent la mortalité par hypothermie. Ces mouvements induisent également une concentration des individus simulés dans des zones productives (comme les upwellings de bord Est) inaccessibles en dérive passive. Ces résultats questionnent la vision classique des juvéniles circulant passivement autour des gyres océaniques et devraient rapidement être pris en compte pour la mise en place de mesures de conservation ciblées visant les tortues marines juvéniles. / Sea turtles are increasingly threatened by the direct and indirect effects of human activities. Their life cycle is complex, shared between various, and often very distant, habitats. Their conservation therefore requires identifying the habitats occupied at each stage of life and the migration routes between these different habitats. While the spatial ecology of adult turtles is relatively well known, particularly through satellite monitoring, the situation is not the same for juveniles which pelagic development phase remains largely unobserved. In that context, numerical simulation constitutes an appropriate tool to explore the dispersal of juvenile sea turtles from their natal beaches. Until now, simulations were mostly performed under the assumption that juveniles disperse passively with oceanic currents. In this PhD thesis we present STAMM (Sea Turtle Active Movement Model), a new model of active dispersal that aims to go beyond the initial hypothesis of passive drift. In STAMM, juvenile sea turtles move under the influence of ocean currents and swimming movements motivated by the search for favorable habitats. This model is applied here to the study of the dispersal of juveniles from three sea turtle populations: leatherback turtles (Dermochelys coriacea) of the Western Pacific and the Northwest Atlantic Oceans, and loggerhead turtles (Caretta caretta) of the Western Indian Ocean. Our results show that, although ocean currents broadly shape juvenile dispersal areas, simulations including habitat-driven movements provide more realistic results than passive drift simulations. Habitat-driven movements prove to deeply structure the spatial and temporal distribution of juveniles. In particular, they induce seasonal latitudinal migrations that reduce cold induce mortality. They also push simulated individuals to concentrate in productive areas that cannot be accessed through pure passive drift. These results challenge the classical view of juveniles circulating passively around oceanic gyres. They should rapidly be taken into account for the implementation of targeted conservation measures concerning juvenile sea turtles.

A interação das tartarugas marinhas da espécie Caretta caretta e Dermochelys coriacea com o espinhel pelágico é um dos fatores que mais causa a mortalidade destes animais no oceano. Estudos com o intuito de quantificar essa interação, bem como os fatores que influenciam a mesma, são crescentes, para os quais é necessário conhecer a distribuição dos animais, e correlacioná-la com variáveis ambientais e operacionais da pesca. O presente estudo visa avaliar e quantificar os padrões espaço-temporais das capturas acidentais das tartarugas marinhas C. caretta e D. coriacea na região Sudeste/Sul do Brasil, com base em dados coletados pelo Projeto TAMAR ICMBio, entre 2003 e 2010, a partir de um programa de observadores à bordo da frota comercial com espinhel pelágico, assim como correlacioná-los com variáveis ambientais, biológicas e operacionais. Para tal, foram utilizados métodos estatísticos, como os Modelos Aditivos Generalizados para Posição, Escala e Forma (GAMLSS). Foram verificadas variações interanuais e sazonais, com destaque para maiores capturas por unidade de esforço (CPUE) no outono. A temperatura superficial do mar foi a variável abiótica de maior correlação com a CPUE de C. caretta, sendo tipo de isca, a variável operacional mais significativa. Para D. coriacea, profundidade e longitude foram os fatores que melhor explicam a CPUE. Padrões de distribuição ontogenética e áreas prioritárias de conservação para essas populações são discutidas, assim como os efeitos potenciais do aquecimento do oceano. O presente estudo deve contribuir para a definição de políticas de conservação marinha e no contexto da abordagem ecossistêmica para a pesca / The interaction between the sea turtles Caretta caretta and Dermochelys coriacea with pelagic longline is one of the factors that cause mortality of these animals in the ocean. Studies in order to quantify this interaction, as well as the factors that influence it, are increasing, focusing mostly on the turtles distribution, and how it correlates with environmental and fishing operational variables. Present study aims to evaluate and quantify the spatio-temporal patterns of the sea turtles C. caretta and D. coriacea bycatch off Southeast/South Brazil, based on data collected by Project TAMAR - ICMBio between 2003 and 2010, from an observer program on-board the commercial pelagic longline fleet, as well as to correlate them with environmental, biological and operational variables,. Statistical methods such as Generalized Additive Models for Location, Scale and Shape (GAMLSS) were applied. Interannual and seasonal variations were observed, with a higher catch per unit effort (CPUE) during fall. The sea surface temperature was the abiotic variable that most correlated with CPUE of C. caretta, being the type of bait the most significant operational variable. For D. coriacea, depth and longitude were the factors that better explained the CPUE. Ontogenetic distribution patterns and priority areas for the species conservation are discussed, as well as the potential effects of ocean warming. This study should contribute to the definition of conservation policies as well as to the ecosystem approach to fisheries context

This project expands the outreach of the Canaveral National Seashore to its visitors, potential visitors, and virtual visitors through its goals in conservancy and preservation of its natural resources. This paper is involved with the current iteration of a series of digital media projects, the Sea Turtle Nest Camera, also known as, Turtle Cam. It details how and why this project was designed to be an ongoing initiative to assist in those goals.

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.