Distribuição espacial e temporal dos insetos e Oligochaeta aquáticos da sub-bacia do Córrego São Pedro, Juiz de Fora, Minas Gerais

Abstract

In order to obtain information about the spatial and temporal variation of Oligochaeta fauna and aquatic insects and to use this information to characterize the environmental quality of Córrego São Pedro Subbasin (which is part of the drainage basin of Paraibuna River, Juiz de Fora city, Minas Gerais state, Brazil) we collected sediment samples at 5 spots along the course of this river. Sampling was carried out between May 2005 and May 2006, and we gathered a total of 143359 species distributed among 88 taxa. Oligochaeta were represented by 4 families (Tubificidae, Naididae, Opistocystidae, and Enchytraeidae) and 29 species. The Tubificidae family, the most abundant one, was composed of 7 species, among which Limnodrilus hoffmeisteri was the most representative in number. Immature individuals made up 57% of the total Tubificidae fauna. Insects were represented by 26 families, among which Chironomidae was the most abundant. Individuals from the genus Chironomus made up 98% of the enthomofauna. The results of the non-parametric Kruskal-wallis test showed a significative difference (P<0.05) in composition and structure of the fauna between collection spots. The Wilcoxon signal test indicated a significative difference (p<0.05) for the fauna during dry and rainy periods. Faunistic structure and composition, as well as the physical and chemical variables analised showed the existence of anthropic impacts and changes in Córrego São Predro Subbasin.