Nitrate, water temperature, conductivity, and transparency drive littoral phytoplankton species composition and biovolume in two reservoirs in the Xingu river

Abstract

Ecological interactions in the littoral zone maintain water quality, biodiversity, and ecological services in freshwater ecosystems. Phytoplankton occupy a central position in the ecosystem due to their sensitivity to environmental changes and ecological importance for ecosystem functioning. Here, we aimed to evaluate dissimilarity in physicochemical characteristics and phytoplankton composition of the littoral zone in two reservoirs of the Belo Monte Hydroelectric Complex. We also investigated the physicochemical factors determining spatial variation in the composition, richness, and biovolume of littoral phytoplankton in the environments studied. The physical and chemical characteristics of the water displayed distinct patterns in the Xingu and Intermediate reservoirs, which drove phytoplankton biovolume and species composition. However, the richness of phytoplankton species was similar in the two reservoirs. More specifically, phytoplankton biovolume and species composition were influenced by nitrate, temperature, conductivity, and transparency. Our study increases understanding of the environmental factors determining spatial variation of littoral phytoplankton communities in reservoirs. This data improves understanding of littoral zones in reservoirs and highlights the importance of littoral phytoplankton in maintaining water quality and ecosystem services in these waterbodies.