Plankton play a key role in biogeochemical cycles in aquatic environments, and their abundance and composition vary spatially and seasonally. We characterised the seasonal dynamics and environmental preferences of freshwater bacteria and microeukaryotes from four pelagic sites in the oligotrophic Lake Baikal and examined the spatio-seasonal niche of closely related taxa. Based on spatio-seasonal patterns, the amplicon sequence variants (ASVs) of bacterial 16S rRNA gene, microeukaryote 18S rRNA g