CHARACTERIZATION OF NESTING BEACHES AND FEEDING AREAS OF MARINE TURTLES AT THE SAN BERNARDO A RCHIPELAGO, COLOMBIAN CARIBBEAN

Abstract

The San Bernardo Archipelago, in the Colombian Caribbean zone, is well recognized for being a sporadic nesting and feeding area for the green, hawksbill and loggerhead turtles. Due to the fact that the San Bernardo Archipelago has outstanding coral areas, marine grasses and sandy beaches and their environmental offers for the marine turtles have not been described yet, it was opportune to carry out this study between July and October of 2002. Thus, this research tends to fill this gap by describing the nesting beaches and feeding areas according to their geomorphologic and biotic aspects and, for the later areas, some oceanographic aspects too. Seven potential nesting beaches and 20 stations on feeding areas were evaluated to identify natural and anthropogenic threats that could affect sea turtles and their habitats. The only species that still nests on these islands is the hawksbill turtle, but its nesting areas are being reduced because of erosion and constructions on the beach. The remaining nesting places observed during the 2002 season were on the southeastern side of Palma island and on the northern side of Tintipán island. In the feeding areas, the majority of stations (n=14) have marine grass with predominance of soft bottom. From these characterizations in the feeding areas, nine sponges and two seaweeds species were described as index species hawksbill turtles feed on. In order to gather information about the marine turtles diet components, five stomach contents of hawskbill turtle and six of green turtle were analyzed. They showed that the sponges Eicionemia sp. and Geodia sp. are the principal diet components (96% dry weight) in the hawksbill turtle diet. In the case of the green turtle, Thalassia testudinum a n d Syringodium  filiforme grasses were identified as index species (98% dry weight); they were the most common during the field observations. The principal threat for sea turtles was the direct capture of adults and juveniles in feeding areas, for what efforts should be directed to reduce the number of poached individuals, to determine the intervention degree and the possible solutions.