Population declines of sea turtles worldwide, driven by overhunting, habitat loss, and other anthropogenic factors have made these animals a global conservation priority. Sea turtle species are particularly susceptible to anthropogenic and natural disturbances due to their complex life traits: female homing and migration, migrations of juveniles and males that remain poorly known, and a strong climatic influence on resources, breeding success and clucth sexratio. São Tomé and Príncipe archipelago in the Gulf of Guinea, West Africa, hosts at least four species of sea turtles, for three of which life-history traits, reproductive behavior and dispersal were assessed for this study: the green turtle (Chelonia mydas), the most abundant species, the hawksbill (Eretmochelys imbricata), which is considered the most threatened population in the Atlantic (both species common to both islands), and the olive ridley (Lepidochelys olivacea), which only occurs in São Tomé island. In this study I integrated various tools and techniques, including site-based monitoring (e.g. on nesting beaches or foraging areas), genetic analyses for both adult and juvenile populations, mark-recapture studies, dispersal simulations as well as stable isotopes analysis, which complemented each other in the assessment of the conservation of each species in the archipelago, including little understood groups such as juveniles and males. Specifically, I showed that São Tomé island hosts important foraging areas that offer a variety of food sources for green turtle juveniles, which are recruited directly from this rookery. For the olive ridley turtle, I characterized the reproductive behavior of the adult population using paternal assessments and showed that males are important mediators of gene flow in this genetically depressed population. Finally, I conducted the first full characterization of spatial and temporal characterization of hawksbill nesting in the archipelago, identifying the key nesting habitats and assessing the levels of human impact that they are exposed to. Overall, the results of this study highlight the high vulnerability of the three species studied in light of limited dispersal, high genetic distinctiveness and exposure to threats
