Effects of Dreissena polymorpha on burrowing ability, mass, and growth rate of Campeloma decisum.

Abstract

An invasive species can drive a native aquatic organism to extinction by limiting the organism's ability to move and accessibility to essential resources. The purpose of this study was to determine if D. polymorpha affect the burrowing ability, mass, and growth rate of C. decisum. We randomly collected 70 C. decisum with and 70 C. decisum without D. polymorpha attached from the sandy substrate of water up to one meter deep in Douglas Lake, Cheboygan County, Michigan. After we marked all C. decisum with an identification number, we measured the burrowing depth in the laboratory and lake, several shell traits, and the number of D. polymorpha on each snail; we calculated the total mass of D. polymorpha and the ratio of D. polymorpha mass to C decisum mass. Burrowing ability was significantly different after one (p < 0.001), two (p < 0.001), and three (p < 0.001) hours of burrowing by C. decisum with and without D. polymorpha attached to the shell, and was lower for C. decisum with D. polymorpha. The difference in mass of C. decisum with and without D. polymorpha did not differ signficantly (p = 0.262). Growth rate was significantly different for C. decisum with and without D. polymorpha (p = 0.004) and was lower for C. decisum with D. polymorpha. We believe that the invasion of D. polymorpha is an urgent problem in Douglas Lake, and we predict that C. decisum, among other snails, will go extinct within the next decade if the rate of invasion of D. polymorpha does not become controlled.