Tolerance changes of the potworm Enchytraeus albidus after long-term exposure to cadmium

Cadmium tolerance in Enchytraeus albidus was assessed for non-acclimatised organisms, as well as populations acclimatised for 18 months to 32, 100 and 320 mg Cd kg dry wt. of standard artificial soil. Despite the increased concentration of metallothionein-like proteins in the acclimatised potworms, no changes in sensitivity to acute and chronic Žjuvenile production. cadmium toxicity could be observed. The 21-day LC50s ranged from 627 for the non-acclimatised enchytraeids to 748 mg Cd kg dry wt. for the organisms acclimatised for 18 months to a cadmium concentration of 320 mg kg dry wt. The 42-day EC50s varied from 96.2 Ž73.6 115. for the organisms acclimatised to 32 mg Cd kg dry wt. to 234 Ž186 290. mg Cd kg dry wt. for those acclimatised to 100 mg Cd kg dry wt., while the value was intermediate for the non-acclimatised organisms and those acclimatised to the highest cadmium concentration. The elevated content of metallothionein-like proteins apparently only served for the detoxification of the increased cadmium body burdens.