Panorama sobre a pesquisa e conservação de tartarugas marinhas no Brasil: contribuições do monitoramento de encalhes e de análises genéticas

Abstract

Genetics is one of the tools recently used for understanding many aspects of sea turtles' life cycle. Stranding monitoring has a great conservation importance. In this context, the present study aimed to: (1) register the diversity, distribution and seasonality of sea turtles on the central-north coast of Rio de Janeiro state, and investigate their major threats in the region; (2) to genetically characterize green turtles incidentally captured by trawling in Itaipu beach, Niteroi and stranded animals between Saquarema and Quissamã, and to evaluate their genetic differences (also among sampled years), natal origins and connectivity, and (3) to genetically characterize loggerhead turtles incidentally captured by pelagic longline fishery and stranded animals in Southeast-Southern coast of Brazil, and to evaluate their genetic differences (inter-annual and among different life stages), natal origins and connectivity. 3,050 sea turtle strandings were reported between 2008 and 2010 in the central-north coast of Rio de Janeiro state, of which 2,728 C. mydas (89.44%), 112 C. caretta (3.67%), 89 L. olivacea (2.92%), 28 E. imbricata (0.92%), 26 D. coriacea (0.85%) and 67 unidentified (2.2%). Strandings were more abundant during winter, dry period and weak upwelling period, which can be related to the occurrence of these species in the region, but also and mostly due to wind conditions. Among animals with any evidence of anthropogenic interaction, 88.59% (N=730) were representative of fishing, 6.92% (N=57) of collision, 2.31% (N=19) of trash ingestion and 2.18% (N=18) of dredging interaction. Among C. mydas samples (N=261) 16 longer mtDNA haplotypes were identified, and among C. caretta (N=265) 13. Mixed Stock Analysis (MSA) showed that Ascension Island, Suriname, Aves Island and Guinea Bissau were the main sources for Rio de Janeiro C. mydas feeding aggregate. Contributions from Trindade Island were possibly underestimated. MSA also indicated that Brazilian nesting colonies were the main sources of C. caretta feeding aggregates in Rio de Janeiro, Rio Grande do Sul and Elevação do Rio Grande, with less expressive contributions from the Pacific (mainly from Australia), North Atlantic and Mediterranean. Differences observed between C. mydas and C. caretta can be directly attributed to behavioral aspects: while juvenile and adult green turtles undertake long migrations among breeding and feeding zones, loggerhead turtles tend to feed near their natal beach, except for oceanic juveniles. For both species, there were no significant genetic differences among years, stranding and bycatch samples, and juveniles/subadults and adults. Given the connectivity among C. mydas and C. caretta Brazilian populations and several other populations in the world, conservation of these species requires collective efforts on a global scale