Beta diversity of phytoplankton functional groups and its response to environmental variables in Chishui River, China

This study adopted Generalized Dissimilarity Modeling (GDM) to analyze the effects of spatial and environmental factors on the total beta diversity of phytoplankton functional groups (FGs) across the Chishui River Basin on the Yunnan-Guizhou Plateau of China. Following Baselga’s partitioning framework, we decomposed beta diversity into turnover and nestedness components and calculated community dissimilarity using the Sørensen dissimilarity coefficient. A total of 16 phytoplankton functional groups were identified throughout the sampling period, including 14 groups detected in the wet season and 11 in the dry season. The total beta diversity of phytoplankton functional groups was markedly higher in the wet season than in the dry season, while no significant seasonal differences were observed in the relative contributions of turnover and nestedness. GDM outputs revealed that hydrodynamic and suspended sediment conditions dominated community variation during the wet season, with environmental filtering acting as the primary structuring driver. Suspended solids and flow velocity constituted the key regulators of wet-season beta diversity, whereas total phosphorus was the dominant limiting factor in the dry season. Additionally, spatial factors exerted weaker explanatory power over beta diversity in the wet season relative to the dry season. This research provides fundamental data support for aquatic ecological health assessment and targeted watershed management planning for the Chishui River Basin.