Origens natais de machos e diferenças no uso do habitat entre machos e fêmeas de tartarugas-oliva (Lepidochelys olivacea) da costa de Sergipe, Brasil

Abstract

Understanding migratory patterns, natal origins, and habitat use by sea turtles is crucial to refining and delineating conservation strategies, particularly during non-reproductive phases. Moreover, knowledge about these characteristics in male sea turtles is scarce due to the difficulty of accessing these animals, which, unlike females, spend their entire lives at sea. The olive ridley sea turtle (Lepidochelys olivacea), classified as “vulnerable” both nationally and internationally, is the most abundant sea turtle species in the world, yet one of the least studied. Sergipe, in northeastern, hosts the main nesting area for this species along the Brazilian coast. Although nesting numbers have increased in recent years, the high number of stranded turtles is concerning for population stability, particularly due to the high mortality rate among males. This high number of male strandings is believed to be due to their presence along the Sergipe coast during the whole year. Additionally, there is a tendency toward female-biased hatchling sex ratios in the region due to high temperatures, suggesting that the male population feeding and reproducing along the Sergipe coast may represent a mixed stock. Based on this, the study aimed to assess the genetic diversity and natal origins of male olive ridleys stranded along the Sergipe coast using the mtDNA control region and to identify preferred habitat use areas for males by analyzing stable carbon and nitrogen isotopes in epidermal tissue. Results show that males have low genetic diversity, with natal origins mainly from Angola, Gabon/São Tomé and Príncipe/Equatorial Guinea; this pattern was already observed for olive ridley populations in adjacent areas, such as Alagoas and Ceará; with the same countries as source areas. Results also suggest that male olive ridleys feeding and reproducing along the Sergipe coast presents habitat use similar to those of females during the reproductive period, but show differences in the postreproductive period, in which females migrate to feeding areas while males remain in the region. Results of this study, although preliminary, provide important information for understanding the ecology, migration patterns, and connectivity of male olive ridley sea turtles in the species' main nesting ground in the Southwest Atlantic.