Assessment of Environmental Stress by the Micronucleus test on Cyprinid Fish as a Model for in Situ Detection of Mutagens in Freshwater

Changes in micronuclei frequency of fish captured from stressed environments may represent a reliable tool in revealing sub lethal effects of the pollutants found in aquatic ecosystems. The response patterns of peripheral erythrocyte micronuclei were assessed in fish caught at Dal Lake and Mansbal Lake which have different pollution levels with the aim to evaluate the suitability of the MN, for the Halics detection of mutagens in freshwaters. As indicator species, Cyprinid fish (Cyprinus carpio and Carassius carassius L.) were used because of their ecological significance. Blood samplings were performed on fish immediately after capture and repeated at different time intervals (15, 30, 45 and 60 days) on the same fish individuals after transfer to clean environment (aquariums) in the laboratory. The MN formation in the peripheral erythrocytes, authenticated by scanning electron microscopy (SEM), was found significantly higher (p < 0.01) in both species of fish caught from Dal Lake in comparison to fish from Mansbal Lake and also from the positive control (EMS, 5mg/L). Cyprinid fish examined after 15, 30, 45 and 60 days of maintenance after capture presented a remarkable decrease resulting in recovery up in MN frequency in comparison with the frequency observed at capture. Results suggested the suitability of the test species used as tools in environmental monitoring programs of risk assessment in fresh water environments.