Tartarugas-verdes ameaçadas de extinção na Bacia Potiguar, Nordeste, Brasil: perspectivas para a conservação

Abstract

The high annual stranding rates of green turtles (Chelonia mydas) recorded in recent years in Brazil, and more specifically in the Potiguar Basin region, bring to light the need to understand the presence of the species in the region, as well as its main threats. In this sense, this study aimed to analyse the pattern of occurrence of the green turtle in the Potiguar Basin, a region between the northern coast of Rio Grande do Norte (RN) and east of Ceará (CE), characterizing the population stocks of the species, as well as as evaluating the impact of anthropogenic debris and the bioaccumulation of chemical elements in the tissues of specimens found stranded in the region. The analysis of the genetic composition showed a great haplotypic diversity of the green turtles of the Potiguar Basin, with a predominance of the two most recorded haplotypes on the coast of the Western South Atlantic (CM-A8 and CM-A5). Through the adaptation of a tool used for diet analysis, the Food Index (IAi), it was possible to access the impact of anthropogenic debris, mainly transparent soft plastic on juvenile green turtles (JUV-I), which is associated with coastal eating habits. and on the surface of the species, where the highest concentrations of plastic fragments occur, associated with floating algae. The evaluation of contamination by chemical elements (THg, Cu, Cd, Ag and Se) in tissues (liver, muscle and kidneys) of green turtles, revealed levels of contamination, still unknown for these animals in the Potiguar Basin, reinforcing the role of sea turtles as sentinels of the quality of the marine ecosystem. Our findings increase the understanding of the composition of C. mydas population stocks on the Brazilian coast, which, associated with the diagnosis of impacts caused by anthropogenic debris and contaminants, especially in less studied areas, such as green turtle feeding sites, contribute to a greater organization of strategies to recompose nesting areas, with a consequent improvement in the threat status of the species in Brazil and in the world.