ACUTE TOXICITY OF IVERMECTIN TO THE LUGWORM ARENICOLA-MARINA

Ivermectin (22,23-dihydroavermectin B1a and B1b), as the commercial Pr emix for Pigs, was found to be acutely toxic to the marine sediment-dw elling polychaete Arenicola marina (10-day LC50 0.023 mg/kg dry weight of sediment, confidence limits 0.018 and 0.027 mg/kg). At all concent rations tested (i.e., 0.006 mg/kg dry weight and above), ivermectin re duced the rate of cast production. Prior exposure to 0.010 mg/kg or mo re reduced the rate at which A. marina was able to rebury in clean sed iment. The results indicate that there is a clear case for targeted fi eld studies at marine salmon farming sites where permission may be giv en to use ivermectin to control ectoparasitic sea lice infections. Cro wn Copyright (C) 1997 Published by Elsevier Science Ltd.