Longitudinal distribution of the ichthyofauna in a tributary of Tiete River with sources on the Basaltic Cuestas of Sao Paulo, Southeastern Brazil

摘要

This work aimed to study the composition and distribution of fish species at four sites along Cabeca River, an affluent of Corum batai River, tributary of Tiete River, intending to better understand the influence of local geomorphology on the occurrence of the species along the river. Using gill nets, trawl net, cast net and sieves, five samples were taken from each site every two months. These data were analyzed from constancy of occurrence, similarity index of Jaccard, rarefaction analysis and descriptive statistical analysis of richness. 4,532 fish individuals belonging to six different orders, 17 families and 65 species were captured. Differences in composition, richness (diversity), abundance and frequency were observed at these sites along the river. The sample site near the mouth of Cabeca River, was richer (49 species) and more abundant than the other three upstream sites, which showed fewer species and equivalent amounts each other (between 22 and 29 species). Moreover, this downstream site had the highest percentage of accessory species, whereas the other samples had a greater number of constant species. Cluster analysis from the Jaccard similarity showed that each site had distinct species composition. Cabeca River basin drains a rugged terrain in the state of Sao Paulo, between the Basaltic Cuestas and Peripheral Depression geomorphologic provinces. In this scenario, waterfalls and rapids influence the distribution, composition and richness of fish species.