title: Trophic relationships and habitat preferences of delphinids from the southeastern Brazilian coast determined by carbon and nitrogen stable isotope composition.
abstract: To investigate the foraging habitats of delphinids in southeastern Brazil, we analyzed stable carbon (δ(13)C) and nitrogen (δ(15)N) isotopes in muscle samples of the following 10 delphinid species: Sotalia guianensis, Stenella frontalis, Tursiops truncatus, Steno bredanensis, Pseudorca crassidens, Delphinus sp., Lagenodelphis hosei, Stenella attenuata, Stenella longirostris and Grampus griseus. We also compared the δ(13)C and δ(15)N values among four populations of S. guianensis. Variation in carbon isotope results from coast to ocean indicated that there was a significant decrease in δ(13)C values from estuarine dolphins to oceanic species. S. guianensis from Guanabara Bay had the highest mean δ(13)C value, while oceanic species showed significantly lower δ(13)C values. The highest δ(15)N values were observed for P. crassidens and T. truncatus, suggesting that these species occupy the highest trophic position among the delphinids studied here. The oceanic species S. attenuata, G. griseus and L. hosei had the lowest δ(15)N values. Stable isotope analysis showed that the three populations of S. guianensis in coastal bays had different δ(13)C values, but similar δ(15)N results. Guiana dolphins from Sepetiba and Ilha Grande bays had different foraging habitat, with specimens from Ilha Grande showing more negative δ(13)C values. This study provides further information on the feeding ecology of delphinids occurring in southeastern Brazil, with evidence of distinctive foraging habitats and the occupation of different ecological niches by these species in the study area.
authors.affiliation: Laboratório de Mamíferos Aquáticos e Bioindicadores "Profa. Izabel Gurgel" (MAQUA), Faculdade de Oceanografia, Universidade do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, RJ, Brazil ; Programa de Pós-Graduação em Ecologia, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ, Brazil ; Laboratório de Radioisótopos Eduardo Penna Franca, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ, Brazil.
authors.forename: Tatiana Lemos
authors.initials: TL
authors.lastname: Bisi
authors.affiliation: Laboratório de Radioisótopos Eduardo Penna Franca, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ, Brazil.
authors.forename: Paulo Renato
authors.initials: PR
authors.lastname: Dorneles
authors.affiliation: Laboratório de Mamíferos Aquáticos e Bioindicadores "Profa. Izabel Gurgel" (MAQUA), Faculdade de Oceanografia, Universidade do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, RJ, Brazil.
authors.forename: José
authors.initials: J
authors.lastname: Lailson-Brito
authors.affiliation: Laboratoire d'Oceanologie - MARE, Université de Liège, Liège, Belgique.
authors.forename: Gilles
authors.initials: G
authors.lastname: Lepoint
authors.affiliation: Laboratório de Mamíferos Aquáticos e Bioindicadores "Profa. Izabel Gurgel" (MAQUA), Faculdade de Oceanografia, Universidade do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, RJ, Brazil.
authors.forename: Alexandre de Freitas
authors.initials: Ade F
authors.lastname: Azevedo
authors.affiliation: Instituto Boto-cinza, Mangaratiba, RJ, Brazil.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Flach
authors.affiliation: Laboratório de Radioisótopos Eduardo Penna Franca, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ, Brazil.
authors.forename: Olaf
authors.initials: O
authors.lastname: Malm
authors.affiliation: Laboratoire d'Oceanologie - MARE, Université de Liège, Liège, Belgique.
authors.forename: Krishna
authors.initials: K
authors.lastname: Das
mesh_terms: D000818:Animals; D001938:Brazil; D002247:Carbon Isotopes / Q000032:analysis*; D004289:Dolphins / Q000502:physiology*; D017753:Ecosystem; D005247:Feeding Behavior / Q000502:physiology*; D018482:Muscle, Skeletal / Q000737:chemistry*; D009587:Nitrogen Isotopes / Q000032:analysis*; D009752:Nutritional Status
chemical_list: D002247:Carbon Isotopes; D009587:Nitrogen Isotopes