The use of stable isotope analyses from skin biopsy samples to assess trophic relationships of sympatric delphinids off Moorea (French Polynesia)

Jeremy Kiszka (1) , Marc Oremus (2) , Pierre Richard (1) , Michael Poole (3) , Vincent Ridoux (1)

1 LIENSs - LIttoral ENvironnement et Sociétés
2 University of Auckland [Auckland]
3 CRIOBE - Centre de recherches insulaires et observatoire de l'environnement

Defining trophic relationships among organisms of a community is critical in ecology. However, the access to data is sometimes difficult, particularly in remote environments. Ecological niche segregation among the most common delphinid species was investigated: the spinner dolphin (Stenella longirostris), the roughed-toothed dolphin (Steno bredanensis), the short-finned pilot whale (Globicephala macrorhynchus), and the melon-headed whale (Peponocephala electra). Resource partitioning was explored by analysing δ13C (reflecting foraging habitats) and δ15N stable isotopes (reflecting trophic level) from skin biopsies collected around Moorea from July to October 2002 to 2004. Results revealed that spinner dolphins had the lowest trophic level. The three other species had similar δ15N signatures. The most significant result is the differentiation of S. longirostris from S. bredanensis and G. macrorhynchus but not from the P. electra. For the latter three species, some degrees of overlap were apparent. For S. longirostris, S. bredanensis and G. macrorhynchus, variation of δ13C and δ15N stable isotope was not significant between sexes. This study suggests that stable isotopes reveal some degree of segregation and overlap within this delphinid community. However, fine-scale segregation processes may be concealed by stable isotope analyses, meaning that traditional dietary analyses investigations are complementary in answering questions related to niche segregation.

Domains: Ecosystems

Jeremy Kiszka, Marc Oremus, Pierre Richard, Michael Poole, Vincent Ridoux. The use of stable isotope analyses from skin biopsy samples to assess trophic relationships of sympatric delphinids off Moorea (French Polynesia). Journal of Experimental Marine Biology and Ecology, 2010, pp.48-54. ⟨hal-00606242⟩