Use of oxygen isotopes in bone carbonate to track home-range of South American sea lions (Otaria flavescens) along the South-west Atlantic.

ZENTENO, L.; CRESPO, E. A.; GODALL, N.; AGUILAR, A.; L.R. DE OLIVEIRA; DRAGO, M; SECCHI, E.; GARCIA, N. A.; CARDONA, L.

Congreso; 26rd. ANNUAL CONFERENCE OF THE EUROPEAN CETACEAN SOCIETY; 2012

Bone apatite grows at a constant temperature in mammals and, hence, variations in the 18O of apatite carbonate reflect changes in the 18O of ingested water. As food is the only relevant source of water for marine mammals, the 18O of their apatite bone is expected to reflect that of their food, which in turn reflects that of the water mass where they live. As a consequence, the 18O of apatite in marine mammal bone is a potentially useful habitat tracer for marine ecosystems. This study departs from this assumption to investigate dispersal patterns of South American sea lions in the south-west Atlantic. Bone samples were collected from the skulls of individuals that were found dead stranded in Brazil (32 males), northern Patagonia (40 males and 39 females) and Tierra del Fuego (19 males and 7 females). Bone samples were grinded and the resulting powder was soaked into a hydrogen peroxide solution to oxidize organic matter. A solution of acetic acid buffered with calcium acetate was later used then for isolating the original structural carbonate from potential contaminants. Finally, samples were analysed using a mass spectrometer. A statistically significant correlation was found between the latitude of the stranding point and the 18O value of adults males (n=39, rp= -0.335, p