Site contributions to phytoplankton beta diversity along two subtropical reservoirs

Information about species diversity, integration of local data, and the dynamics of regional diversity is essential for understanding the mechanisms that maintain diversity in biological communities, especially in aquatic environments, which have extensive connectivity. Here, we used phytoplankton community data from two subtropical reservoirs and evaluated the site contributions to phytoplankton beta diversity. We partitioned beta diversity into two mechanisms, replacement and differences in species richness and abundance, and we related to environmental heterogeneity. We tested whether there is a predominance of replacement or differences in richness and abundance in beta diversity, and whether environmental heterogeneity predicts beta diversity and its components. Our results indicated the temporal and spatial variation of the environmental conditions of the reservoirs. The species replacement was prevalent in lentic sites, while differences in richness and abundance contributed to lotic sites. Dissolved oxygen, total phosphorus, euphotic zone light availability, orthophosphate, water flow, and total dissolved solids were predictors of beta diversity and its components. Thus, studies that consider the local and regional variability of species in the function of environmental heterogeneity are essential in understanding ecological determinants and should be considered for the conservation of aquatic biodiversity and the maintenance of ecosystem services in reservoirs.