Fish assemblages respond to forest cover in small Amazonian basins |
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| Institution: | 1. Universidade do Estado do Rio de Janeiro (UERJ), IBRAG, Departamento de Ecologia, Laboratório de Ecologia de Peixes, Rua São Francisco Xavier 524, Maracanã, CEP 20550-011, Rio de Janeiro, RJ, Brazil;2. Universidade Federal Fluminense (UFF), Instituto do Noroeste Fluminense de Educação Superior, Avenida João Jasbick, s/nº, Aeroporto, CEP 28470-000, Santo Antônio de Pádua, RJ, Brazil;3. Universidade Federal do Rio de Janeiro (UFRJ), Instituto de Biodiversidade e Sustentabilidade (NUPEM), CP 119331, CEP 27910-970, Macaé, RJ, Brazil |
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| Abstract: | The removal of native forest affects stream characteristics, processes, and organisms at the local scale. We compared the structure of fish assemblages between microbasins impacted by deforestation and those in pristine condition in the Amazonian Machado River basin, Brazil. Fish were collected with seine and dip nets along an 80-m stretch of 28 streams. At each site, we recorded physical, chemical, and land-water ecotone variables. We collected 6,586 specimens of 109 species, being 39 and 18 of them exclusively of forested and deforested streams, respectively. Non-significant differences were found for abundance and species richness between forested and deforested streams. A total of four main trophic groups were identified. Carnivores were more abundant in forested streams, whereas herbivores, omnivores and detritivores species were the most abundant in deforested streams. The deforested streams showed higher abundance and richness of algae and periphyton consumers, while forested streams presented higher abundance and richness of invertebrate consumers. Forested streams presented longer foodchains, higher occurrence and abundance of species that have more specialized habits and are intolerant to degraded environments, whereas generalist and tolerant species predominated in deforested streams. We conclude that species composition in Amazonian streams predictably responds to the degree of forest cover. |
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| Keywords: | Conservation Deforestation Land use Machado River Neotropical fish |
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