Foraging ecology of the critically endangered hawksbill sea turtle in the Gulf of Guinea

Vieira, Sara; Ferreira-Airaud, Betânia; Baptista, Vânia; Tiwari, Manjula; Castilho, Rita; Teodosio, Maria

http://hdl.handle.net/10400.1/29174

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Autores

Vieira, Sara

Ferreira-Airaud, Betânia

Resumo(s)

Understanding the ecological roles of critically endangered species is essential for effective conservation planning. This study investigates the foraging ecology and nutritional condition of the hawksbill sea turtle (Eretmochelys imbricata) in São Tomé Island, a key foraging ground in the Gulf of Guinea. We integrated stable isotope analyses of epidermal tissues with RNA/DNA ratios to assess habitat use, trophic position, and physiological status across life stages. Thirty hawksbill turtles (juveniles and adults) were sampled during in-water surveys conducted between 2021 and 2022 using minimally invasive techniques. Prey samples were also collected for isotopic baselines. Carbon (δ13C) and nitrogen (δ15N) values revealed significant ontogenetic shifts, with adults occupying broader isotopic niches. While sponges remained the dominant food source at both stages, adults exhibited greater dietary diversity, including red algae and tunicates. Juveniles showed higher spatial and temporal fidelity, suggesting stronger residency patterns. Estimated trophic positions ranged from 2.57 to 2.79, consistent with secondary consumers. RNA/DNA ratios indicated higher metabolic activity in juveniles and males, while lower values in females likely reflect reproductive metabolic suppression. These findings represent the first integrative assessment of hawksbill turtle foraging and nutritional condition in the region. The study provides critical baseline data on one of the most genetically isolated and endangered hawksbill populations worldwide. This approach enhances understanding of their ecological function and supports the development of targeted conservation actions that account for life-stage–specific needs, contributing to adaptive management and long-term recovery of this critically endangered population.