抄録
The toxicities of copper, zinc and chlorine to free-swimming cercariae of five trematode taxa were assayed. The hazard ratios of the test solutions of copper, zinc and chlorine to the control were calculated using the Cox proportional hazard model. Copper significantly reduced the survival rates of Centrocestus armatus, Cercaria nipponensis and Metagonimus spp at 1.0×10-1 mg · l-1 and the encystment rate of Notocotylus magniovatus at 1.0 mg · l-1. Zinc reduced the survival rate of Cer. nipponensis at 5.0 mg · l-1 and the encystment rate of N. magniovatus at 1.0 mg · l-1 but it did not affect those of the other three species even at the highest concentration tested (1.0×10 mg · l-1). Chlorine reduced the survival rates of Cen. armatus, Cer. nipponensis and Genarchopsis goppo at 4.2×102 mg · l-1, and those of Metagonimus spp. at 2.1×103 mg · l-1. At the chlorine concentration of 4.2×102 mg · l-1, N. magniovatus cercariae did not die during the experiment, but they ultimately did not metamorphose into metacercariae. Chlorine at lower concentrations increased the survival rates of Cer. nipponensis, Metagonimus spp. and G. goppo. These results indicate that copper influences the survival of some trematode species even at a concentration lower than the quality standard for drinking water, and therefore these trematode species are useful bioindicators.
