Acute mortality of soft shell clam, Mya arenaria, larvae, green sea urchin, Strongylocentrotus droenbachiensis, larvae, and rotifers, Brachionus plicatilis, exposed to cypermethrin (ExcisTM)

摘要

The acute effects of cypermethrin on M. arenaria larvae, S. droenbachiensis larvae, and B. plicatilis, were studied in the laboratory. Zooplankton were exposed for 1, 6, and 12 h to different concentrations of cypermethrin, at water salinity levelsof 32±0.6 ppt and a temperature of 12deg C. Clams, urchins, and rotifers were exposed to cypermethrin concentrations of 0, 0.005, 0.05, 0.5, 5.0, 50, 500, 5000, and 50 000μg/litre. These concentrations correspond to 0, 1/1000, 1/100, 1/10, 1, 10, 100, 1000, and 10 000 times the manufacturer's recommended treatment concentration. Only at concentrations of between 10-10 000 times greater than the recommended treatment dose of 5μg/litre, did cypermethrin treatment cause statistically significant mortality in the clam larvae (P<0.05), sea urchin larvae (P<0.05) and rotifers (P<0.05). The LC50 values for soft shell clam larvae mortality after 1, 6 and 12 h of exposure were calculated at～13 500,～11 800, and～10 700μg/litre, respectively. For the sea urchinlarvae the LC50 values after exposure for 1, 6 and 12 h treatment durations were～215 000,～39 700, and～16 950μg/litre, respectively. All LC50 values for the rotifer were >50 000μg/litre. It is concluded that soft shell clam larvae, green sea urchinlarvae, and rotifers are not significantly affected by exposure to cypermethrin concentrations below the manufacturer's recommended treatment dose.