Marco García Cruz
The Reproductive Population of Green Turtles (Chelonia mydas) on Isla de Aves, Venezuela: Understanding Genetic Connectivity, Recent History, and Demographic Parameters in a protected Area to Inform recovery Goals in Endangered Green Turtle Populations in the Western Atlantic.
SUMMARY
The green turtle (Chelonia mydas) is a marine reptile listed as an endangered species. Some of the threats against these animals include: overexploitation of females and eggs on nesting beaches, directed and incidental fishing in foraging areas, pollution, modification of nesting and feeding habitats, and diseases. The variability of these threats in the Caribbean has resulted in different demographic scenarios where some populations are in decline while others are growing. Among these scenarios the Aves Island Wildlife Refuge (AV) is potentially one of the most isolated, and has been protected for many years allowing for the development of more favorable trends. To find out if the biological and ecological characteristics of green turtles may be taken as an example in other populations highly affected, it is necessary to understand their delimitation, reassess their demographic parameters and studying their ecological interactions. To do this we: a) analyzed mtDNA sequences data to re-evaluate the site fidelity of females, and to assess for the first time the male philopatry of this species in the Caribbean and western Atlantic; (b) we analyzed 26 years of capture-recapture data to estimate survival and population trends; and (c) we conduct an analysis of the diversity and abundance of the potentially vectors epibionts of diseases for this species. We have found that the males from AV have a philopatric behavior to their native region in the choice of their breeding area very similar to females choices of nesting beaches to lay eggs. Demographic studies support earlier suggestions that the population of AV has been growing during the past 26 years. However, the annual survival is lower than other green turtle population over the world and it is most affected by factors limiting survival, possibly in the feeding areas where illegal fishing persists. We found that adults of C. mydas in AV have low epibionts diversity compared with juveniles of the species, probably due to physical removal during courtship and mating. Also, we found that females from AV used oceanic habitats more than males as pre-nesting and pre-mating migrations. Finally, the presence of Ozobranchus. branquiatus is not a good predictor of Fibropapillomatosis, being the most important disturbance/pollution. Although these results support the importance of focused long-term conservation programs to protect breeding sites, and provide data that can serve as a reference point in the recovery of other species, they also highlight the need to extend the efforts of management to feeding to ensure the recovery of green turtle populations.
