Toxic effects of cadmium-spiked sediments in Tubifex tubifex: Enzyme biomarkers measurements

Effects of cadmium-spiked sediment exposure (0.001, 0.01, and 0.1 mg{bullet operator}kg^-1 dm.) on the oligochaete Tubifex tubifex were evaluated. CdCl₂ which is easily soluble in water was used as a cadmium source. Catalase (CAT) and gluthatione S-transferase (GST) enzymes belonging to the antioxidant system which protects organisms from harmful impact caused by reactive oxygen species and carboxylesterase (CarE) which takes part in the phase I of detoxification were analyzed. Enzyme activity was measured in tissues of T. tubifex after 4, 24, 72, and 168 h of exposition. Cadmium, generally, caused an increase in T. tubifex CarE activity by comparing the control sediment prepared in accordance with the OECD 233 guideline. CAT activity demonstrates a decrease in a dose-responsive manner after 4-h exposure and an increase after 24-h exposure. No significant changes in GST activity under sublethal concentrations of cadmium were reported.