<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>

<p dir="ltr">The Leatherback Sea Turtle (<i>Dermochelys coriacea</i>) is a globally vulnerable species suffering from declining populations due to anthropogenic pressures. There are seven recognized Leatherback Sea Turtle regional management units; however, the Southeast Atlantic unit is considered data deficient. Bioko Island, Equatorial Guinea, is a primary nesting rookery for the Southeast Atlantic regional management unit and has some of the world’s highest numbers of nesting Leatherback Sea Turtles. Despite Bioko Island’s importance to the species, little is known about the nesting ecology or post-nesting migratory movement and behaviors of its nesting Leatherback Sea Turtles. Here, I present the findings of two individual research projects on the nesting ecology of Leatherback Sea Turtles on Bioko Island. First, I explored the long-term clutch success rates (i.e., hatching success and emergence success) of <i>in situ</i> Leatherback Sea Turtle nests on Bioko and searched for associated variables. I found significant spatiotemporal variation over nine nesting seasons, likely driven by individual beach characteristics rather than regional climate patterns. Secondly, I described a novel effort to use solar-reliant towable transmitters to track the post-nesting migratory movements and behaviors of Leatherback Sea Turtles nesting on Bioko Island. With the results from each project, I make recommendations to further the current conservation and research initiatives of Leatherback Sea Turtles.</p>

Les organismes font face à des compromis entre leur reproduction, leur maintenance et leur survie, dont découlent des stratégies adaptatives énergétiques, comportementales et écologiques.Ce travail de thèse propose de préciser les stratégies de reproduction chez la tortue luth Dermochelys coriacea nidifiant en Guyane. Nous avons étudié les caractéristiques maternelles, les performances de reproduction et les potentiels liens existants entre la migration et la reproduction chez une population d’individus d’identité connue, suivis grâce à un suivi longitudinal original combinant biométrie, physiologie et biologie moléculaire.Premièrement nous montrons que les tortues luth opèrent comme des reproducteurs sur capital, i.e., leur reproduction repose sur les ressources stockées sous forme de réserves corporelles pendant la migration précédant la saison de ponte. D’autre part, nous suggérons que les femelles ajustent la durée de leur migration en fonction des conditions océanographiques rencontrées pendant la migration. Ceci leur permettrait, à l’échelle de la vie, de répondre au compromis entre la reproduction en cours et les reproductions futures. Enfin, notre démarche souligne l’importance de prendre en compte les caractéristiques individuelles dans la compréhension des stratégies de reproduction, et de manière ultime pour l’établissement de modèles réalistes de la dynamique des populations, notamment dans le cas d’espèces emblématiques telles que les tortues marines. / Organisms face trade-offs between their reproduction, maintenance and survival, from which result adaptative strategies at the energetics, behavioural and ecological levels.This PhD work investigates the reproductive strategies used by leatherback turtles, Dermochelys coriacea, nesting in French Guiana. We investigated maternal characteristics, reproductive output, and the possible links between migration and reproduction in a population of known identity, studied through a unique longitudinal monitoring, based on complementary approaches combining biometry, physiology and molecular biology.First, we found that leatherback turtles are capital breeders, i.e. females’ reproductive output displayed during their nesting season relies on body reserves previously stored during their migration. Second, we suggested that leatherback females adjust the duration of the migration according to the oceanographic conditions they experienced during migration. At a lifetime scale, this may allow females to face the trade-off between current and future reproductions. Finally, our approach highlights the importance to take into account individual characteristics in order to better understand reproductive strategies, and further assess realistic models of population dynamics, particularly when considering emblematic species such as sea turtles.

Made available in DSpace on 2014-07-29T16:24:21Z (GMT). No. of bitstreams: 1 taryana.pdf: 5876234 bytes, checksum: 626e6debe969770d6329c335e12d0cad (MD5) Previous issue date: 2006-08-24 / The Species Palicourea coriacea (Cham) K,Shum is a species little know, it is belonging to the Rubiaceae family, popularly known as douradinha. The popular use medicine in the therapy of kidneys illnesses. The popular name douradinha is associated with the color of the bracts and of the stem and the species occurs in Cerrado s Bioma, however in different environments. Studies about the genetic diversity and its distribution in natural populations of P. coriacea are of extreme importance for the definition of adequate strategies of handling and cultivation, however they do not exist in literature, studies of this nature. This work had as objective to evaluate the genetic structure from nine natural populations of P. coriacea, collected in States of Goiás and Bahia and to evaluate the genetic diversity of these populations through markers RAPD. The P. coriacea species presented one high level of genetic diversity, or heterozygosity waited by Nei (1972) that it varied between 0,259 and 0,338 in the populations, with equal on average value the 0,296. The AMOVA disclosed that 23% of the total variability is meeting each other between populations. Although the estimates of apparent gene flow (Nm) have disclosed values inferior to one, on the other hand, equal the 0,83. The analyses of Bayesian Statistics had disclosed to a value of f (FIS) equal the 0,98 suggesting the possibility of this species has behavior like autogamous species. The analyses of grouping of the populations using Bayesian and AMOVA statistics disclosed that it does not exist a correlation between geographic distance and genetic distance all the nine populations they grouping, eventually, not obeying its geographic origin. Then, the hypothesis previously formulated of that geographically next populations would be genetic next, was discarded for the results gotten for the Mantel test where it got a correlation of 0,155. In addition, this relatively high inter populations differentiation allows to recommend to a strategy ex situ of the genetic variability using the biggest possible number of populations. In what, the conservation says respect in situ must be taken in account characteristic genetic and demographic of this species considering that this fact implies in the possibility of a continuous evolution and in the development of new adaptable strategies. It is necessary to have conscience on the distribution of the genetic diversity of these areas with intention to not only promote polities for preservation of found natural populations in national parks, but yes to private preservation of the legal reserves and properties. / A espécie Palicourea coriacea (Cham.) K. Schum é uma espécie pouco conhecida cientificamente, pertencente à família Rubiaceae, popularmente conhecida como douradinha. É utilizada pela medicina popular na terapia de doenças renais. O nome popular douradinha está associado à cor das brácteas e do caule e a espécie ocorre no bioma Cerrado, porém em diferentes fitofisionomias. Estudos sobre a diversidade genética e sua distribuição em populações naturais de P. coriacea são de extrema importância para a definição de estratégias adequadas de manejo e cultivo, porém não existem, na literatura, estudos dessa natureza. Este trabalho teve como objetivo avaliar a estrutura genética de nove populações naturais de P. coriacea, coletadas nos Estados de Goiás e Bahia e avaliar a diversidade genética dessas populações utilizando marcadores RAPD. A espécie P. coriacea apresentou um alto nível de diversidade genética, ou heterozigosidade esperada de Nei (1972) que variou entre 0,259 e 0,338 nas populações, com um total geral igual a 0,296. A AMOVA revelou que 23 % da variabilidade total se encontram entre populações e 77 % se encontra dentro de populações. As estimativas de fluxo gênico aparente (Nm) foram inferiores a um, ou seja, igual a 0,83. As análises do índice de fixação (f) por abordagem bayesiana forneceram valores médio igual a 0,98 sugerindo a possibilidade dessa espécie se comportar como uma espécie autógama. As análises de divergência genética e padrão espacial das populações utilizando as matrizes de &#952;B e &#934;ST par a par revelou que não existe uma correlação entre distância geográfica e distância genética todas as nove populações se agrupam aleatoriamente, não obedecendo a sua origem geográfica. Assim, a hipótese previamente formulada de que populações geograficamente próximas teriam que ser geneticamente próximas, foi descartada pelos resultados obtidos no teste de Mantel onde a correlação foi igual a 0,155. Assim essa diferenciação interpopulacional relativamente alta permite recomendar uma estratégia de amostragem para a conservação ex situ da variabilidade genética, utilizando o maior número de populações possível. No que diz respeito a conservação in situ, deve ser levado em conta características genéticas e demográficas dessa espécie, considerando que esse fato implica na possibilidade de uma evolução contínua e no desenvolvimento de novas estratégias adaptativas. É necessário ter conhecimento sobre a distribuição da diversidade genética destas áreas com o intuito de auxiliar nas políticas para preservação não somente de populações naturais encontradas em parques nacionais, mas também preservação das reservas legais e propriedades privadas.

Les organismes font face à des compromis entre leur reproduction, leur maintenance et leur survie, dont découlent des stratégies adaptatives énergétiques, comportementales et écologiques.Ce travail de thèse propose de préciser les stratégies de reproduction chez la tortue luth Dermochelys coriacea nidifiant en Guyane. Nous avons étudié les caractéristiques maternelles, les performances de reproduction et les potentiels liens existants entre la migration et la reproduction chez une population d'individus d'identité connue, suivis grâce à un suivi longitudinal original combinant biométrie, physiologie et biologie moléculaire.Premièrement nous montrons que les tortues luth opèrent comme des reproducteurs sur capital, i.e., leur reproduction repose sur les ressources stockées sous forme de réserves corporelles pendant la migration précédant la saison de ponte. D'autre part, nous suggérons que les femelles ajustent la durée de leur migration en fonction des conditions océanographiques rencontrées pendant la migration. Ceci leur permettrait, à l'échelle de la vie, de répondre au compromis entre la reproduction en cours et les reproductions futures. Enfin, notre démarche souligne l'importance de prendre en compte les caractéristiques individuelles dans la compréhension des stratégies de reproduction, et de manière ultime pour l'établissement de modèles réalistes de la dynamique des populations, notamment dans le cas d'espèces emblématiques telles que les tortues marines.