Correlating incidences of Dreissena polymorpha attachment with trematode parasitism in Stagnicola emarginata snails.

Abstract

The invasive zebra mussel (Dreissena polymorpha) has negatively impacted many northern Michigan aquatic species in the past twenty years (Strayer, 2009). One of the species affected has been Stagnicola emerginata, a freshwater snail. This species of snail also acts as the intermediate host for a number of parasitic schistosome species which increase the size of the snail, possibly making them more vulnerable to zebra mussel colonization (Horak et al., 2002). The purpose of this study was to determine if there is a relationship between Schistosomatidae parasitism in the freshwater snail Stagnicola emarginata and attachment of Dreissena polymorpha. Snails were collected from Douglas Lake in northern Michigan lake, shed under artificial lighting to induce cercarial emergence, and observed to determine parasite infection. D. polymorpha attachment was noted before snail release. Findings indicate no significant relationship between schistosome parasitism and the presence of D. polymorpha. We suggest the absence of a relationship may be due to the schistosomes acting as prudent parasites.