Cheias anuais alteram o padrão da riqueza e diversidade beta da comunidade fitoplanctônica: um estudo de 20 anos em um igarapé amazônico

Abstract

The flood pulse is widely recognized as a significant structuring force for terrestrial and aquatic communities in floodplains. This study focuses on unraveling the dynamics of the phytoplankton community in a clear-water stream in the Amazon. The proximity of the stream to a bauxite mining area, coupled with its crucial role in supporting local communities, amplifies the importance of this research. Over 20 years, we conducted quarterly collections at three points along the stream, resulting in an extensive dataset comprising 240 campaigns. Our main objective was to uncover patterns of phytoplankton diversity and interannual structuring. We assessed species turnover and temporal beta diversity during different phases of the flood pulse, with a special focus on high-water periods. To evaluate our hypotheses, we employed robust methodology, analyzing species richness, density, and beta diversity through comprehensive calculations and generalized least squares models to assess the effects of the flood pulse on these predictors. The large dataset enhanced predictive capacity for local environmental issues, and by quantifying species turnover and beta diversity during different flood pulse phases, we gained insights into the underlying temporal mechanisms of phytoplankton community dynamics. Our study has significant implications for understanding floodplain ecosystems and emphasizes the need for environmental monitoring of this ecosystem. By shedding light on the intricate dynamics of phytoplankton communities, we hope to provide valuable insights for conservation efforts and policy decision-making. Our results will contribute to the sustainable management of this ecosystem, ensuring its preservation for future generations.