The invasive fish Acestrorhynchus pantaneiro Menezes, 1992 in Southern Brazil: Occurrence and food niche overlap with two native species |
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| Authors: | E B Neuhaus D A Antonetti U H Schulz |
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| Institution: | 1. Museu Nacional, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil;2. Laboratório de Ictiologia, Museu de Ciências e Tecnologia, PUCRS, Porto Alegre, RS, Brazil;3. Laboratório de Ecologia de Peixes, Universidade do Vale do Rio dos Sinos, S?o Leopoldo, Rio Grande do Sul, Brazil |
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| Abstract: | Acestrorhynchus pantaneiro is an invasive species in the Patos Lagoon system in South Brazil. The aim of the study was to document the expansion of the occurrence range of A. pantaneiro in southern Brazil and to analyze the diet and food feeding overlap with the two native species Oligosarcus robustus and O. jenynsii. Occurrence data were based on fish collections databases and collected material. Fish for the stomach analysis were captured in the Jacuí and Sinos rivers from 2007 to 2009 by gillnetting and electrofishing. Food uptake was quantified by frequency of occurrence and relative abundance of the prey items. Food niche overlap was estimated by the Pianka Index. Database records indicated a rapid expansion of the occurrence range in all principal basins of the southernmost state of Rio Grande do Sul in Brazil. Food niche overlap was greatest between A. pantaneiro and O. robustus (Ojk = .970). Both species fed predominantly on small Characids. O. jenynsii ingested predominantly insects and crustaceans and, consequently, had low food niche overlap when compared with the two other species. Results indicate that the expansion of A. pantaneiro occurrence range may principally affect O. robustus populations. |
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