Anthropic effects on the fish community of Ribeirão Claro, Rio Claro, SP, Brazil
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Data
2007-02-01
Autores
Ferreira, FC. [UNESP]
Petrere Jr., M. [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Instituto Internacional de Ecologia
Resumo
Com o objetivo de verificar o efeito de alterações antrópicas, como o despejo de esgotos sobre a comunidade de peixes do Ribeirão Claro, SP, foram feitas coletas mensais em três pontos ao longo do rio (cabeceira, meio e foz) entre dezembro de 2003 e março de 2004, período reprodutivo para a maioria das espécies da região. O Ribeirão Claro apresentou boa composição e variedade em sua comunidade íctia, possuindo espécies raramente observadas em trabalhos na região, como Paravandellia oxyfera e Callichthys callichthys. Os índices de diversidade e equitabilidade apresentaram diferentes resultados quando considerado o peso ou número de indivíduos, além de não evidenciarem o comportamento típico de aumento da diversidade no sentido cabeceira-foz, nem a conseqüente perda de riqueza taxonômica no trecho impactado pelo despejo de esgoto doméstico. Sua interpretação deve ser feita com cautela, considerando os diversos aspectos incluídos em seus cálculos. Assim como os índices de diversidade, a similaridade de Morisita-Horn não ressaltou a grande diferença na comunidade da foz do Ribeirão Claro, em especial com relação ao trecho médio do rio. Fica evidente o declínio na riqueza de espécies no trecho poluído e a alteração em sua composição trófica, apresentando alta dominância de espécies piscívoras.
The effect of anthropic alterations such as drain discharge on a fish community was studied in the Ribeirão Claro River, municipality of Rio Claro, State of São Paulo, southeastern Brazil. Samples were made monthly in three different points along the river (headwaters, mid course, and confluence) between December, 2003 and March, 2004, which is the reproductive period for the majority of the species. The fish community of the Ribeirão Claro River showed a fair composition and diversity, with species rarely observed in studies made in the region, such as Paravandellia oxyfera and Callichthys callichthys. Indices of diversity and equitability showed different results when weight or the number of individuals were considered. Moreover, these indices did not reveal the typical increase in diversity from the headwaters toward the confluence, nor the loss of richness in the part altered by drain discharge. An interpretation should be made with caution, taking into account the diverse factors included in the computation. Similar to the diversity indices, the Morisita-Horn similarity index did not reveal a great difference in the fish community of the confluence of the river, mainly in relation to its mid course. The decline of species richness and trophic composition alteration in the disturbed part is clear, which shows a great dominance of piscivorous species.
The effect of anthropic alterations such as drain discharge on a fish community was studied in the Ribeirão Claro River, municipality of Rio Claro, State of São Paulo, southeastern Brazil. Samples were made monthly in three different points along the river (headwaters, mid course, and confluence) between December, 2003 and March, 2004, which is the reproductive period for the majority of the species. The fish community of the Ribeirão Claro River showed a fair composition and diversity, with species rarely observed in studies made in the region, such as Paravandellia oxyfera and Callichthys callichthys. Indices of diversity and equitability showed different results when weight or the number of individuals were considered. Moreover, these indices did not reveal the typical increase in diversity from the headwaters toward the confluence, nor the loss of richness in the part altered by drain discharge. An interpretation should be made with caution, taking into account the diverse factors included in the computation. Similar to the diversity indices, the Morisita-Horn similarity index did not reveal a great difference in the fish community of the confluence of the river, mainly in relation to its mid course. The decline of species richness and trophic composition alteration in the disturbed part is clear, which shows a great dominance of piscivorous species.
Descrição
Palavras-chave
Índices de diversidade, comunidade de peixes de água doce, efeitos da poluição, Ribeirão Claro, Brasil, diversity indices, freshwater fish community, pollution effects, Ribeirão Claro, Brazil
Como citar
Brazilian Journal of Biology. Instituto Internacional de Ecologia, v. 67, n. 1, p. 23-32, 2007.