Evaluating the isotopic niche of beaked whales from the southwestern South Atlantic and Southern Oceans

RICCIALDELLI, L; PASO VIOLA, MN; PANARELLO, HO; GOODALL, RNP

MARINE ECOLOGY PROGRESS SERIES

INTER-RESEARCH

Año: 2017

0171-8630

The study of species´ niches is important in ecological research to understand how speciesand their habitat respond to rapid environmental changes and is especially challenging for oceanic andcryptic species such as beaked whales. We analyzed δ C and δ N values in bone collagen to studyinterspecific variation in the isotopic niche of 8 species of beaked whales (Berardius arnuxii, Hyperoodonplanifrons, Mesoplodon bowdoini, M. grayi, M. hectori, M. layardii, Tasmacetus shepherdi and Ziphiuscavirostris) that stranded along the coast of Tierra del Fuego between 1967 and 2009. We found aspatial (e.g. feeding areas) and trophic (e.g. diet) isotopic segregation among these species, which areknown to inhabit subantarctic to Antarctic waters. Isotopic analysis showed that, while spatialsegregation seems to operate to a higher degree in species of the same genus (e.g. Mesoplodon),trophic differentiation allowed the co-existence of sympatric species from different genera (e.g. Ziphius,Hyperodoon and Mesoplodon). Our results agree with previous studies based on stomach contentanalyses. In addition to different trophic strategies, variation in habitat preferences were also revealed bystable isotope analysis. An isotopic trend in both δ C and δ N values was found among beakedwhales and possible prey species in accordance with previous information on other cetacean speciesknown to have feeding areas in different ocean regions. The present study provides valuable ecologicalinformation about elusive and little-studied beaked whale species inhabiting the world?s southernmostoceans.