Proceedings of the International scientific and practical conference ―Science at the Frontier of Civilizations: Challenges and Perspectives‖ (December 27-29, 2025) / Publisher website: www.naukainfo.com. – Helsinki, Finland, 2026. – 252 p.

24 of eutrophic and organically polluted waters; Cyanophyta (cyanobacteria) — indicative of increased trophic status and the potential for water ―blooms‖; Chrysophyta (golden algae) — indicators of relatively clean and weakly mineralized waters. Diatoms were represented by the genera Melosira, Navicula, Pinnularia, and Nitzschia. Their dominance in the Seversky Donets River confirms the high mineralization and stability of hydrochemical parameters characteristic of lowland rivers. A specific feature of the revealed composition is the dominance of species of the β-mesosaprobic zone, indicating moderate organic pollution. In stagnant water bodies (Haidarivskyi and Pioneer ponds), the following genera were widely represented: Chlamydomonas, Ankistrodesmus, Enteromorpha, and Spirogyra. Their presence indicates active biological production and accumulation of organic matter. Representatives of the genera Euglena and Trachelomonas were recorded mainly in ponds and in the Pechenihy Reservoir, indicating the development of eutrophic processes. The detection of Euglena granulata and Trachelomonas armata reflects elevated concentrations of organic substances. The genera Anabaena and Oscillatoria occurred unevenly. A significant abundance of A. flos-aquae in the Pechenihy Reservoir indicates the potential for intensive water ―blooms,‖ which is a sign of high saprobity. Based on the abundance and diversity of indicator species, the following trend was established: 1. Lake Bile — the highest proportion of oligosaprobic species, presence of Chrysophyta; the cleanest water body. 2. Pioneer Pond — diversity of golden and green algae, moderate β-mesosaprobity. 3. Haidarivskyi Pond — slightly higher saprobity level, pronounced signs of eutrophication. 4. Seversky Donets River — dominance of β-mesosaprobic diatoms, moderate pollution.