Influência da riqueza de espécies de peixes no padrão ecomorfológico da assembleia em meso-habitat de riachos.

Abstract

Streams are formed by a mosaic of mesohabitats (riffles, runs and pools) delimited among themselves by different compositions of geomorphological and hydrological characteristics. These characteristics influence the distribution of fish species in the channel, as they act as environmental filters, selecting them mainly by their body shape. The distribution of morphological traits in the multivariate space can be considered an indicator of the diversification of niches and ecological functions existing in a given ecosystem. Studies have shown that the number of coexisting species produces changes in the diversity of forms or in the pattern of interspecific similarity within specific taxonomic groups. This study was carried out in small streams in the hydrographic basins of the Ivaí and Pirapó Rivers, with the objective of identifying the ecomorphological pattern of the fish assemblage in mesohabitats of headwater streams according to their taxonomic richness. Principal Component and Variance Analyzes, as well as simple regressions were performed to test the hypotheses, to compare averages between values found by assemblies generated by random permutations with observed assemblies. The results showed that, for riffles and runs, the increase in richness promoted greater packing of species in the ecomorphological space of these mesohabitats, increasing the interspecific similarity without changing the total ecomorphological volume and that this behavior differs from that found by chance, while in pools the structure ecomorphology did not vary according to richness.