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Sazonalidade reprodutora e origem geográfica de tartarugas-verdes (Chelonia Mydas) na África Ocidental
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Abstract(s)
Este trabalho reúne dois estudos complementares sobre a ecologia e conservação das tartarugas-verdes (Chelonia mydas) na África Ocidental, com foco nas populações da Ilha de Poilão, na Guiné-Bissau e de duas áreas de alimentação no Senegal. O primeiro capítulo teve como objetivo comparar, pela primeira vez, o sucesso reprodutivo, na época seca (janeiro a março) e na época de chuva (julho a outubro), na Ilha de Poilão. Monitorizaram-se 118 ninhos na época de chuva e oito na época seca, analisando parâmetros como sucesso de desova, eclosão, emergência, tamanho das posturas e das crias, e taxa de predação. Não se verificaram diferenças significativas entre épocas, contudo, observou-se um sucesso de eclosão atipicamente baixo na época de chuva de 2024, possivelmente devido à maior inundação dos ninhos. O segundo capítulo teve como objetivo caracterizar geneticamente as tartarugas-verdes que se alimentam no Parque Nacional do Delta do Saloum e na Área Marinha Protegida de Joal-Fadiouth, no Senegal, através da análise do ADN mitocondrial (região D-loop). Foram identificados cinco haplótipos, com predominância do haplótipo CM-A8.1 (88,8%). A análise Mixed-stock analysis estimou que 80,7% das tartarugas provêm da colónia de Poilão, evidenciando uma forte conectividade migratória entre as duas áreas. Os resultados obtidos reforçam a importância da Ilha de Poilão como colónia de nidificação de relevância global e do Senegal como área chave de alimentação, fornecendo informações essenciais para a elaboração de estratégias integradas de conservação e gestão da espécie no Atlântico.
Palavras-
This work brings together two complementary studies about the ecology and conservation of green turtles (Chelonia mydas) in West Africa, focusing on populations from Poilão Island, Guinea-Bissau, and foraging grounds in Senegal. The objective of the first chapter is to compare, for the first time, the reproductive success during the dry season (January–March) and the rainy season (July–October) at Poilão Island. A total of 118 nests were monitored during the rainy season and eight during the dry season, assessing parameters such as laying success, hatching success, emergence success, clutch size, hatchling size, and predation rate. No significant differences were found between seasons, however, an atypically low hatching success was recorded in the 2024 rainy season, possibly due to increased nest flooding. The objective of the second chapter was to characterize the genetic composition the green turtles feeding in the Saloum Delta National Park and the Joal-Fadiouth Marine Protected Area, Senegal, through mitochondrial DNA (D-loop region) analysis. Five haplotypes were identified, with CM-A8.1 predominating (88.8%). Mixed-stock analysis estimated that 80.7% of the turtles originate from the Poilão rookery, indicating strong migratory connectivity between the two areas. The results highlight the importance of Poilão Island as a globally significant nesting colony and Senegal as a key foraging ground, providing essential information for the development of integrated conservation and management strategies for the species in the Atlantic.
This work brings together two complementary studies about the ecology and conservation of green turtles (Chelonia mydas) in West Africa, focusing on populations from Poilão Island, Guinea-Bissau, and foraging grounds in Senegal. The objective of the first chapter is to compare, for the first time, the reproductive success during the dry season (January–March) and the rainy season (July–October) at Poilão Island. A total of 118 nests were monitored during the rainy season and eight during the dry season, assessing parameters such as laying success, hatching success, emergence success, clutch size, hatchling size, and predation rate. No significant differences were found between seasons, however, an atypically low hatching success was recorded in the 2024 rainy season, possibly due to increased nest flooding. The objective of the second chapter was to characterize the genetic composition the green turtles feeding in the Saloum Delta National Park and the Joal-Fadiouth Marine Protected Area, Senegal, through mitochondrial DNA (D-loop region) analysis. Five haplotypes were identified, with CM-A8.1 predominating (88.8%). Mixed-stock analysis estimated that 80.7% of the turtles originate from the Poilão rookery, indicating strong migratory connectivity between the two areas. The results highlight the importance of Poilão Island as a globally significant nesting colony and Senegal as a key foraging ground, providing essential information for the development of integrated conservation and management strategies for the species in the Atlantic.
Description
Dissertação de Mestrado apresentada no Ispa – Instituto Universitário para obtenção de grau de Mestre na especialidade de Biologia Marinha e Conservação
Keywords
Tartarugas-verdes Sucesso reprodutivo Ilha de Poilão Áreas de alimentação Mixed-stock analysis Green turtles Reproductive success Poilão Island Foraging ground Mixed-stock analysis