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Niche overlap and diet composition of three sympatric coastal dolphin species in the southwest Atlantic Ocean
Author(s) -
Teixeira Clarissa R.,
Botta Silvina,
DauraJorge Fábio G.,
Pereira Luiza B.,
Newsome Seth D.,
SimõesLopes Paulo C.
Publication year - 2021
Publication title -
marine mammal science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.723
H-Index - 78
eISSN - 1748-7692
pISSN - 0824-0469
DOI - 10.1111/mms.12726
Subject(s) - sympatric speciation , bottlenose dolphin , foraging , ecological niche , biology , predation , niche , pelagic zone , ecology , demersal zone , cetacea , niche differentiation , trophic level , bycatch , apex predator , competition (biology) , habitat , fishery , fishing
Abstract Sympatric species are expected to differ in ecological requirements to minimize niche overlap and avoid competition. Here we assess the trophic interactions among three coexisting dolphin species from southern Brazil: the franciscana dolphin ( Pontoporia blainvillei ), the Guiana dolphin ( Sotalia guianensis ), and the Lahille's bottlenose dolphin ( Tursiops truncatus gephyreus ). We evaluated temporal variation in carbon (δ 13 C) and nitrogen (δ 15 N) isotope values of bone collagen to examine potential dietary shifts resulting from increased fishing activity over the past three decades. We estimated the degree of niche overlap among these species and the contribution of potential prey sources to their diet. δ 15 N values were consistent among species and across years, while δ 13 C values increased for Guiana dolphins and decreased for bottlenose dolphins, suggesting changes in diet and/or foraging habitats through time. The similar δ 13 C and δ 15 N values and the high niche overlap between Guiana and bottlenose dolphins indicate that these species are primarily feeding on demersal prey. The franciscana diet is primarily composed of pelagic prey, resulting in a lower niche overlap in comparison with the other dolphin species. Our study provides further information about the foraging ecology of this unique dolphin community in southern Brazil with implications for its management and conservation.