Abstract
Over recent years it has been established that pollutants can have a significant impact on host-parasite systems in the aquatic environment, so much so that it has been proposed that parasite fauna may be a useful parameter to monitor water quality. Surprisingly, with perhaps the exception of trematodes and bioaccumulation in adult acanthocephalans, detailed observations on the interaction between helminths, particularly cestodes, and pollutants such as heavy metals, are lacking. In this study, eggs of the carp tapeworm, Bothriocephalus acheilognathi were exposed to a range of cadmium concentrations (0.1, 10, 100 and 10,000μg/L) and coracidial hatching and survival assessed. Results indicated that the egg is highly resistant to heavy metal pollution and hatching occurs even at 10,000μg/L. In contrast, the activity of the liberated coracidium significantly decreased after 1h exposure to cadmium at 10 and 100μg/L. Electron microscopic X-ray microanalysis of parasite eggs exposed to 1000 and 10,000μg/L cadmium revealed that cadmium accumulates on the surface of the egg and does not penetrate detectably into the enclosed coracidium. This means that the parasite eggs may be able to withstand a heavy metal pollutant incident.