Expedition to the Angara cascade reservoirs from August 22 to September 3, 2024

Within the RSF project “Microeukaryote Communities in Reservoirs of the Angara Cascade” (led by Prof. Ye.V. Likhoshway), a research expedition to the Bratsk, Ust-Ilimsk, and Boguchansk reservoirs was carried out from August 22 to September 3, 2024. The expedition included researchers Cand. Sc. (Biology) A.M. Marchenkov (head of the team), Cand. Sc. (Biology) Yu.P. Galachyants, V.A. Mukha and driver F.A. Zamkovoy. The ship captains K.V. Stolyarov (Bratskoye), V.T. Shalimov (Ust-Ilimskoye), and P.P. Shipunov (Boguchanskoye) assisted in water sampling in the reservoirs.

Water samples were taken by Niskin bathometer from depths up to 10 m. Nine samples were taken from the Bratskoye reservoir, including tributaries of the Oka and Iya rivers; nine samples from the Ust-Ilimskoye reservoir; and eight samples from the Boguchanskoye reservoir. The total number of samples was 26. Water transparency was determined by Secchi disk, water temperature and pH were measured by field instrument at the time of sampling. Water samples were concentrated onto filters for further investigation of samples by scanning electron microscopy, filtered and fixed for quantitative analysis of phytoplankton composition by light microscopy, and deposited onto filters for further DNA extraction and metabarcoding of microeukaryotes, and frozen for hydrochemical analysis of biogen composition.

Surface water temperature in the Bratskoye reservoir varied from 21.6 to 22.7 °С, pH - 8.1-8.26, transparency - from 3.5 to 10 meters.

The surface water temperature in the Ust-Ilimskoye reservoir was 18.3-20.5 °C, pH - 7.5-8.3, transparency - 4.5-7 meters.

The surface water temperature in the Boguchanskoye reservoir was 18.1-19.7 °C, pH was 7.35-7.47, and transparency was 3-4.5 meters.