Taxonomic and functional responses of bats to habitat flooding by an Amazonian mega-dam

Abstract

Hydroelectric dams are among the main cause of anthropogenic impacts in tropical environments. Damming interrupts the continuity of the river and produces the flooding of adjacent terrestrial ecosystems. Despite the negative effects on terrestrial and aquatic biodiversity, studies of the impacts of hydroelectric dams on species and community functional responses to flooding are scarce. Here, we evaluated the effects of river damming on taxonomic and functional diversity of phyllostomid bats sampled before (flooded sites) and after (unflooded sites) the construction of a mega hydroelectric dam in the southwestern of the Brazilian Amazon. The flooding of the lowlands significantly increased the taxonomic and functional α-diversity, as well as the species- and the community-level functional uniqueness of the bat assemblages, reflecting a reduction in the abundance of functional redundant species. Based on functional trait composition, we detected an increase in the frequency of animalivorous bats, and a reduction in phytophagous bats. Pre- and post-dam temporal differences show that functional β-diversity shifts were more determined by replacement of traits weighted by species abundance than by the loss or gain of traits. Functional traits linked to trophic level, body mass, and diet proved to be powerful indicators of the bat community’s responses to temporal changes caused by run-of-the-river dams, which degrade riparian and várzea forests. Plans to expand the electric power matrix in Brazil include the construction of several dams, potentially flooding large areas of várzea forests. We demonstrate the importance of the várzea and the riparian forests to phytophagous bats to guarantee the ecological functions they perform. © 2022, The Author(s), under exclusive licence to Springer Nature B.V.