During the cruise, hydrobiological, microbiological and hydrochemical samples were collected to determine the composition and distribution of food aquatic organisms - zooplankton, zoobenthos; the level of development and productivity of phytoplankton; the quality of the environment and assessment of chemical pollution of waters, as well as the collection of primary hydrological and hydrochemical (temperature, electrical conductivity, turbidity, pH, oxygen content) data characterizing the habitat of aquatic biological resources at 10 monitoring stations in the lake's water area. A noticeable increase in the water level of Ilmen was noted compared to the same period in 2024, as well as a pronounced unevenness in the distribution of water "blooming" caused by the mass development of cyanobacteria in the water area of the reservoir: the southern part of Ilmen in the zone of influence of the Lovat River waters was distinguished by increased color and low abundance of Cyanophyceae.
Additionally, in order to study the overgrown complex of hydrobionts, studies of the littoral areas in the western part of Ilmen were continued: a description of plant communities was carried out, samples of phytoplankton, zooplankton, microbial communities, zooperiphyton and macrozoobenthos were collected. In the open littoral of the lake, thickets of reed Phragmites austrális were recorded. This species has not been reliably recorded in the composition of macrophyte communities of the reservoir for a long time.
Specialists of the branches began office processing of field materials, based on the results of which an assessment of the habitat and food supply of fish of a large fishery reservoir will be made.
Press service of VNIRO
