Impactos de reservatórios sobre a ictiofauna: simulação da perda de diversidade funcional e filogenética

Abstract

The dams forming reservoirs are among the most impressive human activities on aquatic biodiversity in river environments. The damming process is so intense, that results in the creation of a new ecosystem. In this study we evaluate the consequences of this type of change to the functional and phylogenetic structure of fish communities, by simulating the loss of species known to be sensitive to the river damming. Were used biological data (related to the taxonomic richness, functional and phylogenetic) obtained in the upper and middle segments of the Rio das Mortes, state of Mato Grosso. We found that the middle river has greater taxonomic richness (t = -3.47, p = 0.013), accompanied by bigger diversity of functional attributes (t = -6.39, p = 0.002) and lines in relation to the upper (t = -8.03; p = 0.001). However, when the effect of the wealth is controlled, the middle river tends to be redundant, however, no differences were observed between the segments with respect to the functional diversity (t = 2.30; p = 0.06) and phylogenetic (t = 1.06; p = 0.33). It was found that the species lost, contributing more than 40% of the river's biodiversity. The damming promotes greater wealth losses (t = -4.94, p = 0.004) and lines (p = 0.03, t = -2.36) in the middle Rio das Mortes in relation to the upper portions, however, functional losses are equivalent between segments (t = -1.20, p = 0.161). There are the phylogenetic losses, which were lower than expected by chance in middle River (t = -3.13, p <0.05) due to loss of entire lines (Pimelodidae), while the upper river were upper than expected by chance (t = 5.02; p <0.04). These changes resulted in the reduction of beta functional and phylogenetic diversity among the segments. Thus, the impacts on fish populations occur in different parts of the river, but in different ways. While the damming results in the loss of many lineages in upper potions in the middle stretches the loss of specific clades is prominent. These changes result in the homogenization of biota between segments of the river, with potential loss of ecosystem services and evolutionary history.