Impacto de barragens sobre a avifauna em áreas sazonalmente alagáveis da Amazônia

Abstract

Amazonia is a mega diverse biome due largely to its environmental heterogeneity. Amazonian floodplains have a particular physiognomy, varying in structure, floristic composition, and ecological characteristics, each associated with the type of water and geomorphology of the rivers that form them. These floodplains sustain several other Amazonian habitats and a rich, specialized, and geographically structured avifauna. Floodplains, however, have been directly impacted by the construction of large hydropower dams, but these impacts are little understood and poorly quantified. My goal was to understand how the permanent flooding caused by large dams affects taxonomic, functional and phylogenetic diversity in two distinct floodplain systems. Using passive acoustic monitoring (PAM), I sampled 35 sites in the Madeira and Xingu rivers, both undisturbed sites and sites affected by the Santo Antônio and Belo Monte hydroelectric dams, respectively. I recorded 202 species in total and although I did not find differences in species richness, I found higher values for phylogenetic and functional diversities in impacted areas. I also found high species turnover between distinct river basins and between impacted and control areas. Undisturbed areas were phylogenetically clustered and functionally more similar than impacted sites. I documented significant patterns of spatial variation in local diversity and regional assemblage structure of floodplain avifauna. Most importantly, we show that absolute diversity measures alone do not characterize the impacts caused by river damming on the biodiversity of Amazonian floodplains. Therefore, monitoring dams' environmental impacts should be standardized to include additional measures of community change and focus on seasonally flooded environments.