Metabarcoding survey of microbial communities along the Angara River reservoir cascade, May-June 2024

This project investigates microbial diversity and biogeographic patterns across a cascade of large boreal reservoirs formed along the Angara River (Russia), from oligotrophic Lake Baikal to the Boguchany Reservoir. Water samples were collected in May-June 2024 at 43 stations spanning Southern Baikal (SB), Irkutsk (IR), Bratsk (BrR), Ust-Ilim (UR), and Boguchany (BgR) reservoirs. Additionally, previously generated amplicon sequencing data from SB and IR (June 2023) were included for interannual comparison. Amplicon libraries were prepared from 16S (V3-V4) and 18S (V8-V9) rRNA gene regions and sequenced using the Illumina MiSeq platform. The study revealed pronounced spatial structuring of bacterial and microeukaryotic communities, shaped by environmental gradients such as nutrient concentrations, electrical conductivity, and water transparency. Regionally enriched ASVs (zOTUs) reflected ecological differences among reservoirs, with upstream systems harboring oligotrophic specialists and downstream reservoirs enriched with eutrophic-associated taxa. This dataset contributes to understanding microbial biogeography in regulated boreal freshwater systems.