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

Authors

  • Ana Paula Madeira Di Beneditto Universidade Estadual do Norte Fluminense – UENF, Centro de Biociências e Biotecnologia – CBB, Laboratório de Ciências Ambientais
  • Carlos Eduardo Rezende Universidade Estadual do Norte Fluminense – UENF, Centro de Biociências e Biotecnologia – CBB, Laboratório de Ciências Ambientais
  • Plínio Barbosa Camargo Universidade de São Paulo – USP, Centro de Energia Nuclear na Agricultura – CENA, Laboratório de Ecologia Isotópica
  • Helena Amaral Kehrig Universidade Estadual do Norte Fluminense – UENF, Centro de Biociências e Biotecnologia – CBB, Laboratório de Ciências Ambientais

Keywords:

trophic niche, marine vertebrates, stable isotopes, Rio de Janeiro, Southwest Atlantic

Abstract

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.

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Published

2013-09-01

How to Cite

Beneditto, A. P. M. D., Rezende, C. E., Camargo, P. B., & Kehrig, H. A. (2013). Trophic niche comparison between two predators in northern Rio de Janeiro State, Brazil: a stable isotopes approach. Biota Neotropica, 13(3). Retrieved from //www.biotaneotropica.org.br/BN/article/view/1255

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