Population dynamics of and larval trematode interactions with Lymnaea tomentosa and the potential for biological control of schistosome dermatitis inBremner Bay, Lake Wanaka, New Zealand

Lymnaea tomentosa, the intermediate host of a schistosome which causes schi stosome dermatitis in Lake Wanaka, was found to depths of 16 m. The snail r ecruits in January, lives for up to 21 months, is associated with all water plant species and is found in areas devoid of macroscopic plants. It is ho st to several trematode species. Avian schistosome infections appear in the spring when echinostome prevalence is low, and a decrease in schistosome p revalence may be correlated with an increase in echinostome prevalence duri ng the summer. A multiple-kind lottery model analysis of parasite species r ichness implies that interspecific interactions may be occurring in the hos t snail during the months of December and January.