Spatial variation of five co-existing siluriformes in an atlantic rain forest drainage

Five species of Siluriformes were registered in the Ubatiba system. Pimelodella lateristriga was the dominant one, followed by Hypostomus gr. punctatus, Rineloricaria sp., Callichthys callichthys and Rhamdia sp. Simple correlation analysis between species density and habitat parameters indicated that hydrology explained density patterns of four species. Pimelodella densities were negatively correlated with pools, Callichthys and Hypostomus densities were positively correlated with runs and Rhamdia densities were positively correlated with riffles; Rineloricaria densities did not respond to any hydrological parameter. Substrata were an important factor to all species, but specific preferences were observed. Marginal vegetation was positively correlated only to Pimelodella densities. Sorensen dissimilarity analysis indicated that site groups, based on both species composition and habitat parameters, were very similar and corroborated the correlation analysis suggesting that Siluriformes composition should be explained by many habitat parameters. Analysis of co-variation of species densities at each sampling occasion showed to be statistically similar in at least all (100%) analysed cases indicating that Siluriformes composition was strongly persistent in time.