Feeding ecology of dusky dolphins Lagenorhynchus obscurus: evidence from stable isotopes

LOIZAGA DE CASTRO, ROCÍO; SAPORITI, FABIANA; VALES, D. G.; GARCIA, N; CARDONA, LUIS; CRESPO ENRIQUE A.

JOURNAL OF MAMMALOGY

ALLIANCE COMMUNICATIONS GROUP DIVISION ALLEN PRESS

Lugar: Lawrence; Año: 2015 vol. 97 p. 310 - 320

0022-2372

The dusky dolphin Lagenorhynchus obscurus occurs in the Southern Hemisphere, where it is restricted to coastal temperate areas. This study aimed to characterize the feeding ecology of dusky dolphins inhabiting northernand central Patagonia by using δ13C and δ15N stable isotope ratios in skin samples. We searched for evidence of geographical and seasonal variation in diet and we explored dietary differences between sexes. Significantdifferences in the stable isotope ratios of dusky dolphins were found among the 4 gulfs under study. Skin samples from Golfo San Matías and Golfo San Jorge were 13C-enriched and 15N-depleted compared to those from Golfo Nuevo and Golfo San José. There was no seasonality in the diet at Golfo Nuevo, and no differences in the diet between sexes in any gulf. Furthermore, Bayesian ellipses of males and females were similar in size and the overlap was mostly symmetrical in Golfo San José and Golfo San Jorge, while in the Golfo San Matías and GolfoNuevo, females had wider ranges of δ15N, suggesting the exploitation of a wider trophic niche. Finally, pelagic fishes and demersal pelagic squids were identified as the main prey for this species of dolphin, although theproportion of each prey varied regionally.