Corbicula fluminea (Corbiculidae, Bivalvia) alters the taxonomic and functional structure of benthic assemblages in neotropical hydropower reservoirs

Abstract

The objective of this study is to understand how the taxonomic and functional structures of benthic macroinvertebrate assemblages respond to variations in the densities of Corbicula fluminea, an invasive species originated in Asia, in neotropical hydropower reservoirs. For that we tested three hypotheses: (1) Sites with higher densities of C. fluminea exclude benthic taxa linked to soft substrates and increase the densities of taxa linked to hard substrates. (2) Sites with higher densities of C. fluminea support higher diversities than those with natural soft substrates. (3) Higher densities of C. fluminea support higher functional diversities than the natural soft substrate sites. Our results show that C. fluminea densities are correlated with changes in the taxonomic structure, namely substitution of burrowing taxa for those related to hard substrates, and with increased functional diversity. No taxonomic index showed significant correlation with C. fluminea density, but the functional indices (Functional Richness, Functional Dispersion and Rao’s Quadratic Entropy) showed significant positive correlations. Our results show that functional traits are more sensitive ecological indicators of biological alteration of physical habitat than those based on taxonomic composition and diversity metrics.