Trophic niche comparison between two predators in northern Rio de Janeiro State, Brazil: a stable isotopes approach

Biota Neotropica

Ana Paula Madeira Di Beneditto¹  Carlos Eduardo Rezende¹  Plínio Barbosa Camargo¹  Helena Amaral Kehrig¹ 

关键词: trophic niche;    marine vertebrates;    stable isotopes;    Rio de Janeiro;    Southwest Atlantic;    nicho trófico;    vertebrados marinhos;    isótopos estáveis;    Rio de Janeiro;    Atlântico Sul Ocidental;   

DOI  :  10.1590/S1676-06032013000300002

来源: SciELO

【 摘 要 】

The trophic niche of the sympatric predators Pontoporia blainvillei(franciscana dolphin) and Trichiurus lepturus (ribbonfish) was compared by stable isotope (δ15N and δ13C) ratios in hepatic and muscular tissues to understand how they co-exist in the northern Rio de Janeiro State (21°30′S-22°15′S), south-eastern Brazil. Dolphin specimens were incidentally captured through commercial gillnet fisheries, while fish specimens were the target of these fisheries. The predators had similar δ15N values in the liver (P. blainvillei: 14.6 ± 1.0‰; T. lepturus: 14.4 ± 0.6‰), which indicates similar trophic position in the recent food intake. However,P. blainvillei showed lighter δ15N values in muscle (13.8 ± 1.0‰) than T. lepturus (15.0 ± 0.4‰), revealing differences in the long term diet that could be related with the prey size ingested. The δ13C signatures showed a preferential inshore and benthic food chain for P. blainvillei (liver: −15.2 ± 0.6‰; muscle: −16.0 ± 0.5‰) and a more offshore and pelagic food chain for T. lepturus(liver: −17.2 ± 0.6‰; muscle: −16.8 ± 0.3‰). The isotopic variances of liver and muscle revealed a broader niche width to P. blainvillei in relation to T. lepturus, with a greater use of available food resources in coastal waters. In the area of study, the differences in habitat use and exploitation of food resources are favoring the predators' coexistence.

【 授权许可】

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