REPRODUCTIVE BIOLOGY AND NEST SITE SELECTION OF THE HAWKSBILL TURTLE, ERETMOCHELYS IMBRICATA, POPULATION OF PRÍNCIPE ISLAND

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Long range gene flow beyond predictions from oceanographic transport in a tropical marine foundation species

Publication . Tavares, Ana I; Assis, Jorge; Larkin, Patrick D.; Creed, Joel C.; Magalhães, Karine; Horta, Paulo; Engelen, Aschwin; Cardoso, Noelo; Barbosa, Castro; Pontes, Samuel; Regalla, Aissa; Almada, Carmen; Ferreira, Rogério; Abdoul, Ba Mamadou; Ebaye, Sidina; Bourweiss, Mohammed; dos Santos, Carmen Van-Dúnem; Patrício, Ana R.; Teodosio, Maria; Santos, Rui; Pearson, Gareth; Serrao, Ester A

The transport of passively dispersed organisms across tropical margins remains poorly understood. Hypotheses of oceanographic transportation potential lack testing with large scale empirical data. To address this gap, we used the seagrass species, Halodule wrightii, which is unique in spanning the entire tropical Atlantic. We tested the hypothesis that genetic differentiation estimated across its large-scale biogeographic range can be predicted by simulated oceanographic transport. The alternative hypothesis posits that dispersal is independent of ocean currents, such as transport by grazers. We compared empirical genetic estimates and modelled predictions of dispersal along the distribution of H. wrightii. We genotyped eight microsatellite loci on 19 populations distributed across Atlantic Africa, Gulf of Mexico, Caribbean, Brazil and developed a biophysical model with high-resolution ocean currents. Genetic data revealed low gene flow and highest differentiation between (1) the Gulf of Mexico and two other regions: (2) Caribbean-Brazil and (3) Atlantic Africa. These two were more genetically similar despite separation by an ocean. The biophysical model indicated low or no probability of passive dispersal among populations and did not match the empirical genetic data. The results support the alternative hypothesis of a role for active dispersal vectors like grazers.

2023-06Journal article

Open access

Size-based differences in isotopic niche width (delta C-13 and delta N-15) of green turtles (Chelonia mydas) nesting on Principe Island, Gulf of Guinea

Publication . Ferreira, Rogério L.; Ceia, Filipe R.; Borges, Teresa C.; Ramos, Jaime A.; Bolten, Alan B.

Within the same population, nesting green turtles (Chelonia mydas) might exploit different niches by exhibiting polymorphic foraging strategies and/or inhabiting geographically distinct foraging areas. This is crucial information for the conservation of this species. Here, we used stable carbon and nitrogen isotope ratios (delta C-13 and delta N-15) to test for differences in a population of green turtles nesting on Principe Island (1 degrees 37 ' N; 7 degrees 24'E), Central Africa. A total of 60 nesting females were sampled on the two main nesting beaches of the island in December 2012. Minimum curved carapace length (CCL) was recorded, and delta C-13 and delta N-15 values were measured in the epidermis of each individual. Overall, CCL varied from 87.0 to 108.0 cm (mean +/- SD =100.0 +/- 5.1), delta C-13 values from -19.4 to -8.6 parts per thousand (-17.3 +/- 1.8) and delta N-15 values from 7.9 to 17.3 parts per thousand (13.6 +/- 1.5). Despite the large variation in both isotopic ratios, their distributions were unimodal, showing an absence of polymorphic foraging strategies and isotopically distinct foraging areas. However, smaller females (< median, 100.8 cm) occupied a much larger isotopic niche (i.e., four times greater) than larger females. These results suggest that nesting green turtles may forage opportunistically on the resources available in each of their foraging home ranges, with smaller females venturing to more isotopic-diversified areas and/or exhibiting broader foraging strategies than larger females. In addition, and in accordance with other studies, findings suggest that the foraging grounds used by the Principe green turtle nesting females are distributed mainly throughout the Gulf of Guinea.

2021-02Journal article

Restricted access

Sea turtle conservation in São Tomé and Príncipe: policies, practices, and insights from a community‐based initiative

Publication . Ferreira, Rogério; Prazeres, Inocêncio A. dos

Unifying research and conservation objectives with the needs of local populations demands a profound understanding of the field. This perspective provides a brief policy and social-cultural context for the conservation of endangered sea turtles in S & atilde;o Tom & eacute; and Pr & iacute;ncipe, Central Africa. It is illustrated by initiatives implemented from the 90s to the 2000s and complemented by a community-based intervention on Pr & iacute;ncipe Island (2010-2014). The intervention focused on awareness-raising, economic-alternatives, capacity-building, and surveillances to deter poaching, collect scientific data, and increase outreach. It contributed to reduce sea turtle exploitation, train local conservationists, and increase awareness to economic alternatives. Securing stakeholders' support is vital for success, and endeavors like this provide a cost-effective approach, aligning biodiversity conservation strategies with local values and aspirations. Overall, this perspective underscores that failure to collaborate with those involved in wildlife subsistence livelihoods often results in delays and setbacks in reducing exploitation, while modest investments in local stewardship can efficiently improve ecosystems and human well-being. This perspective provides a policy and social-cultural context for sea turtle conservation in S & atilde;o Tom & eacute; and Pr & iacute;ncipe and it is illustrated by a community-based initiative on the smaller island of Pr & iacute;ncipe. To achieve progress, it is not enough to legislate, effective enforcement, raising awareness, and demonstrating the economic benefits of nonconsumptive use of sea turtles to local communities and authorities are also essential. Overall, it is shown here how local stewardship can inform conservation science and practice, promote social justice, and efficiently improve both ecosystems and human well-being.

2024-06-18Journal article

Open access