Relationship among landuse and composition of aquatic insects of four basins of São Paulo State

Abstract

Four watersheds with different degrees of human occupation had their communities of aquatic insects analyzed in relation to the landuses, terrain slope as well as chemical and physical variables of water. The watersheds studied were Alto Paranapanema, Peixe, Aguapei and São José dos Dourados. Samples of aquatic insects were taken with baskets filled with artificial substrates, during August and October/2002. Eighteen samples were taken from eachriver and the aquatic insects were identified until family level and counted. To analyze the results, total and percentage numbers of individuals and taxons were used, as well as community indeces. Information about the watersheds were generated from digital maps. Thirty-two families were identified, Elmidae, Leptohyphidae, Leptophlebiidae, Chironomidae, Simuliidae and Hydropsychidae showed numeric dominance. Ten chemical and physical variablestested were able to characterize the rivers; percentages of the main landuses and terrain slope were calculated. Pearson’s correlation index, analysis of variance and analysis of correspondence were used in order to establish the relationship between abiotic components and the entomofauna. The study showed that the land use condition immediately adjacent tothe sampling site is the most important factor influencing that fauna.

Key words: aquatic macroinvertebrates, lotic environments, riparian forest, rivers, Southern.