CEST2025

Aquatic ecosystems are highly sensitive to environmental changes, especially in conflict areas, where military actions release various hazardous substances into water bodies. These pollutants pose long-term risks to both human health and aquatic life due to their persistence and bioaccumulation potential. Among aquatic organisms, primary producers respond rapidly to environmental disturbances, making them effective indicators of short- and long-term pollution. Diatoms in particular are valuable indicators for assessing exposure to pollutants such as metals due to their short generation time and sensitivity to environmental stressors. The aim of this study was to evaluate the vulnerability and tolerance of the pollution-tolerant diatom Nitzschia palea to a metal mixture and to assess its potential for monitoring water quality in war-affected aquatic ecosystems in Ukraine. Six different concentrations of a metal mixture comprising Ni (II), Zn (II), Cr (III), Cu (II) were tested under laboratory conditions. The result revealed that exposure to high metal concentrations (≥20 times higher than the maximum permissible concentrations for EU inland waters) significantly suppressed the growth of N. palea and induced morphological changes, such as deformation of valves. In addition, changes in the levels of photosynthetic pigments, malondialdehyde (MDA) and antioxidants were observed. These morphological and biochemical changes indicate that even pollution-tolerant diatom species can be adversely affected by high levels of pollution. The ability of N. palea to show measurable responses to metal exposure, despite its known tolerance, highlights its importance as a bioindicator in polluted waters to assess long-term ecological changes and/or chronic exposure effects. These findings contribute to a better understanding of ecosystem ecological risks in war-affected water bodies, and support the development of effective pollution mitigation strategies in conflict areas such as Ukraine. Acknowledgement This work was funded by NATO Science for Peace and Security Programme “Creating a Strategy for Assessing and Restoring War-affected Aquatic Ecosystem” (No G6085).