Evaluating the isotopic niche of beaked whales from the southwestern south atlantic and southern oceans

• Main Authors: Riccialdelli, L., Natalia Paso Viola, M., Panarello, H.O., Goodall, R.N.P.
• Format: Journal/Newspaper
• Language: unknown
• Subjects: Polar waters; Subantarctic waters; Trophic niche; Ziphiidae; δ13C; δ15N; bone; carbon isotope; cetacean; collagen; habitat selection; interspecific variation; isotopic analysis; niche partitioning; nitrogen isotope; stable isotope; stomach content; trophic level; whale; Argentina; Atlantic Ocean; Atlantic Ocean (South); Southern Ocean; Tierra del Fuego [(PRV) Argentina]; Berardius arnuxii; Cetacea; Hyperoodon planifrons; Mesoplodon; Mesoplodon bowdoini; Mesoplodon grayi; Mesoplodon hectori; Mesoplodon layardii; Tasmacetus shepherdi; Ziphius; Ziphius cavirostris; Antarc*; Antarctic; Tierra del Fuego
• Online Access: https://hdl.handle.net/20.500.12110/paper_01718630_v581_n_p183_Riccialdelli

The study of species' niches is becoming increasingly important in ecological research with the growing need to understand how species and their habitat respond to rapid environmental changes. This kind of study is especially challenging in the case of oceanic and cryptic species such as beaked whales. We analyzed δ13C and δ15N values in bone collagen to study interspecific variation in the isotopic niche of 8 species of beaked whales (Berardius arnuxii, Hyperoodon planifrons, Mesoplodon bowdoini, M. grayi, M. hectori, M. layardii, Tasmacetus shepherdi and Ziphius cavirostris) that stranded along the coast of Tierra del Fuego, Argentina, between 1967 and 2009. We found a spatial (e.g. feeding areas) and trophic (e.g. diet) isotopic segregation among these species, which are known to inhabit subantarctic to Antarctic waters. Iso-topic analysis showed that, while spatial segregation 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 content analyses. In addition to different trophic strategies, variation in habitat preferences were also revealed by stable isotope analysis. An isotopic trend in both δ13C and δ15N values was found among beaked whales and possible prey species in accordance with previous information on other cetacean species known to have feeding areas in different ocean regions. The present study provides valuable ecological information about elusive and little-studied beaked whale species inhabiting the world's southernmost oceans. © Inter-Research 2017.