Determinantes ambientais da diversidade funcional de comunidades de peixes de riachos

Abstract

The knowledge of environmental-trait relationship is relevant to the understanding of the processes organizing the biological communities. Different functional traits of the species may be related to distinct environmental gradients, revealing the importance of the different mechanisms structuring communities. In this context, we evaluated the association between functional trait diversity with environmental gradients in different spatial scales. For this, we studied fish communities from 29 sampling streams belonging to the Santa Teresa river subbasin, Upper Tocantins river system. The sampling was carried out with electrofishing in 80 meters long reaches. We calculated the functional diversity (MPD, MNTD and Rao) related to two niche dimensions: habitat use and trophic ecology. Environmental variables used as predictors of functional diversity represented environmental aspects of three spatial scales, inner habitat, ecotone and landscape. The association between environmental variables with the functional trait diversity was evaluated from multiple regressions, whose models were compared using the Akaike Information Criterion (AIC). Inner habitat and ecotone models were better predictors of diversity for both niche dimensions. The taxonomic diversity had low predictive power. Our results indicate that the species-habitat relationship is determined strongly by the species traits. Physical habitat structure and the ecotone are the best predictors of the functional diversity. Therefore, the local scale would be the most relevant for the management and for the functioning of aquatic biodiversity in streams.