Skin d13C and d15N reveal spatial and temporal patterns of habitat and resource use by free-ranging odontocetes from the southwestern Atlantic Ocean
Troina, G.C.; Botta, S.; Dehairs, F.; Di Tullio, J.C.; Elskens, M.; Secchi, E.R. (2020). Skin d13C and d15N reveal spatial and temporal patterns of habitat and resource use by free-ranging odontocetes from the southwestern Atlantic Ocean. Mar. Biol. (Berl.) 167(12): 186. https://hdl.handle.net/10.1007/s00227-020-03805-8
In: Marine Biology: International Journal on Life in Oceans and Coastal Waters. Springer: Heidelberg; Berlin. ISSN 0025-3162; e-ISSN 1432-1793
Large diversity and abundance of cetacean species occur along the Brazilian outer continental shelf and slope waters. In the present study, we analyzed carbon (d13C) and nitrogen (d15N) stable isotopes in skin biopsies of ten odontocete species (Delphinidae and Physeteridae) to assess the intra- and inter-specific patterns in the use of resources along the region. Our isotopic analysis allowed us to identify two potential subpopulations of Stenella frontalis. High core isotopic niche overlap between S. frontalis from the southern range of the study area and Delphinus delphis, especially in spring, suggested that they share similar resources and rely on spatiotemporal segregation to achieve niche differentiation and to minimize competition. Our isotopic data also pointed to high similarity among Tursiops truncatus, S. frontalis, and Globicephala melas in the use of resources. Steno bredanensis had the highest d15N and d13C, which agrees with its occurrence in neritic waters. S. longirostris showed consistently low d15N values, indicating that they feed at relatively lower trophic levels, and lack of niche overlap with most delphinid species, except S. attenuata. Orcinus orca and G. melas had very similar d13C and d15N values, that were consistent with feeding in offshore waters. d13C and d15N in Physeter macrocephalus suggested that individuals feed on similar trophic levels, but over a wide spatial range. The analyses of stable isotopes in skin biopsies helped us to refine our knowledge about the intra-specific resource and habitat use, ecological niches, and the trophic interactions amongst co-occurring cetaceans from the oceanic waters of the subtropical western South Atlantic.
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