What are you eating? A stable isotope insight into the trophic ecology of short-beaked common dolphins in the Southwestern Atlantic Ocean

LOIZAGA DE CASTRO, ROCÍO; SAPORITI, FABIANA; VALES, DAMIÁN GUSTAVO; GARCÍA, NÉSTOR ANÍBAL; CARDONA, LUIS; CRESPO, ENRIQUE ALBERTO

ZEITSCHRIFT FUR SAUGETIERKUNDE-INTERNATIONAL JOURNAL OF MAMMALIAN BIOLOGY

Elsevier

Año: 2016 vol. 81 p. 571 - 578

0044-3468

As the feeding habits of marine mammals are particularly difficult to observe, stable isotope analysis has become an essential tool to investigate several aspects of dolphin?s trophic ecology. Short-beaked common dolphins (Delphinus delphis) occur off Argentina coastline from 36ºS to 42ºS, but nothing is known about latitudinal changes in diet. A stable isotope analysis has been performed on three shortbeaked common dolphins groups: Buenos Aires group (n = 20), Golfo San Matías inshore group (n = 24), and Golfo San Matías offshore group (n = 16). Highly significant differences in average d15N-skin values were found among the three groups of dolphins considered. Differences were also statistically significant for the average d13C-skin and Suess corrected d13C-skin values. Furthermore, no significant differences were found in the d13C-skin values of the dolphins from the inshore group sampled during summer and winter seasons at Golfo San Matías, although the d15N-skin values changes seasonally, suggesting that probably dolphins forage at a higher trophic level in summer. The SIAR model indicated that juvenile Argentine hake (Merluccius hubbsi) had the highest mean feasible contribution to the diet of short-beaked common dolphins inhabiting the continental shelf off Buenos Aires and northern Patagonia, whereas the Argentine anchovy (Engraulis anchoita) did it for short-beaked common dolphins inhabiting the Golfo San Matías The results obtained in this study increase the knowledge of trophic ecology for high trophic level predators such as short-beaked common dolphins along the Argentina coast in support of effective conservation and management programs.