Functional erosion and trait loss in fish assemblages from Neotropical reservoirs: The man beyond the environment

Abstract

AbstractAnthropogenic impacts are altering ecosystems, especially aquatic habitats, resulting in the loss of critical biodiversity. This study aimed to evaluate the influence of human pressure, as surrogated by the human footprint index (HFI), on the functional diversity of fish assemblages from 109 Neotropical reservoirs while considering covariates such as temperature, flooded area and age since damming. We assessed two components of functional diversity (richness and dispersion) and the specific trait composition of each fish assemblage. We found that both components of fish functional diversity decreased with increasing human pressure and that this relationship was stronger in reservoirs near large cities. There was a positive relationship between functional diversity and reservoir area, and a negative relationship between functional diversity and reservoir age. We also observed strong relationships between all the explanatory variables and functional traits, particularly for the HFI. We can infer that the ichthyofaunas of those reservoirs under higher human pressure are likely undergoing a simplification process along with homogenization of functional diversity.