A Final Report to the Minnesota Department of Natural Resources: Non-Game Division Preliminary Survey of pulmonate Snails of Central Minnesota

Aquatic snails were collected at 148 sites from various wetland habitats in central Minnesota between May and September, 1988. These data were used to determine the distribution, environmental preference and parasite-intermediate host relationships of lymnaeid snails found within the study area. Lymnaeids generally preferred still water of near neutral pH with a small particle size substrate. However, individual lymnaeid species appeared to have more specific requirements. Lymnaea megasoma and L. exilis seemed to prefer slightly acid water. Lymnaea catascopium appeared to prefer deeper open water of lakes and slow moving rivers. Lymnaea caperata and L. (Fossaria) spp. preferred temporary wetlands and mud flats. Due to the drought of 1988, habitat destruction may have strongly influenced distribution of these amphibious species. Species which occur in shallow temporary wetlands may therefore have a wider distribution than this study indicates. The distribution of all lymnaeid species collected was compared to the approximate distribution of Fascioloides magna. This is a common trematode parasite of white-tailed deer in the Northeastern portion of Minnesota. Its life cycle includes lymnaeid snails as intermediate hosts. No strong correlation was found between the range of any snail species and that of the fluke. We were able to infect L. palustris, L. caperata, and L. catascopium (a new host record) in the laboratory. This suggests that more complex factors than intermediate host distribution govern the distribution of F. magna in the state.