文摘
The impact of a drought on freshwater snail and trematode communities was investigated in a lake. Before the drought, 15 gastropod species (Valvatidae, Planorbidae, Lymnaeidae, Ancylidae, Physidae) and 10 trematode species (cercariaeum, xiphidiocercariae, echinostome, furcocercariae, notocotyle, lophocercous) were recorded. The rate of parasitism was 5.13% and there were 11 host species. The 2 major consequences of desiccation were the disappearance of snails, except Valvata piscinalis and Lymnaea peregra, and the absence of trematodes infecting the surviving snails. As soon as favourable conditions were restored, the littoral area was recolonized, first by hygrophilic and amphibious species, second by aquatic species. Nine months after the drought, the gastropod community was restored. Recolonization by the trematodes was delayed compared with that of gastropods. During the study, the overall prevalence was equal to 0.36% and only 4 trematode species and 5 host species were recorded. Because of the great variability of freshwater ecosystems, long-term studies are necessary to understand the dynamics of snail and trematode populations and determine the regulatory effect of parasitism in the field.