Composi？？o e distribui？？o dos macroinvertebrados em diferentes substratos de fundo de um riacho no Município de Itatinga, S？o Paulo, Brasil

the distribution pattern of aquatic organisms results from the interaction of the habit, the physical conditions of the habitat (substrate, flow, turbulence) and the food availability. the purpose of this study is to know the composition and to understand the pattern of distribution of the animal community of a tropical stream. the collections were accomplished in a tributary of the basin of paranapanema, located in the municipal district of itatinga, s？o paulo. when analyzed the occurrence in different types of substrate - vegetal, rocky and sandy - we found a larger density in the rocky substrate and larger diversity in the vegetal substrate. in the three substrata, the invertebrates of the class insecta, and mainly the order diptera, prevailed in abundance and diversity of species. of this order, in the vegetal and rocky substrate prevailed the families chironomidae and simuliidae and in the sediment, the family chironomidae. between the chironomidae was found several genera, with many individuals, of the subfamily ortocladiinae.