August 5, 2025

Radioactive Contamination of Water Bodies: Bioindication and Adaptation of Aquatic Organisms in the Remote Period After the Chernobyl Disaster

Key Points

MAIN FINDING: Aquatic ecosystems in the Chornobyl zone show significant changes due to long-term radioactive contamination.
KEY EVIDENCE: Daphnia magna vitality dropped to 40–55% in contaminated areas, while enzyme activity in fish increased by 50–70%.
APPROACH: The study utilized bioindication methods and analyzed the effects of long-lived radionuclides on aquatic organisms.
SIGNIFICANCE: Findings support development of monitoring systems and ecological rehabilitation for affected water bodies.

Abstract

This study presents an assessment of the long-term radioecological impact on aquatic ecosystems in the zone affected by the Chornobyl disaster nearly 40 years after the accident. The research covers water bodies with varying levels of radionuclide contamination, including riverine and lacustrine sites within the Polissia region and control areas outside the direct zone of radioactive influence. The spatial distribution of long-lived radionuclides (137 Cs and 90 Sr) in water, bottom sediments, and aquatic organisms was investigated, enabling an evaluation of their bioaccumulation, mobility, and ecotoxicological pressure on biota. Modern bioindication methods were applied using model organisms – Daphnia magna and fish of the Cyprinidae family. The vitality of invertebrates and the activity of antioxidant enzymes (superoxide dismutase and catalase) in fish tissues were analyzed as indicators of oxidative stress. In contaminated locations, Daphnia magna vitality decreased to 40–55% compared to control conditions. Enzyme activity in fish increased by 50–70%, indicating the activation of adaptive protective mechanisms. In the most contaminated sites, a decline in enzymatic activity was recorded despite elevated radionuclide concentrations, suggesting depletion of compensatory capacities and potential disruption of homeostasis. Significant correlations were established between ¹37Cs levels in water and enzyme activity in fish (r = 0. 91, p < 0. 01), as well as between radionuclide concentrations and Daphnia vitality (r = –0. 87, p < 0. 05). The obtained results provide a foundation for developing long-term bioindication-based monitoring systems, ecological rehabilitation of contaminated water bodies, and risk assessment for biodiversity in radiation-transformed environments.

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