Substratum preference and the distribution and abundance of the freshwater mollusk, Elimia livescens, in Douglas Lake, Michigan.

Abstract

The purpose of this study was to quantify the substrate preference of Elimia livescens. We investigated if a linear relationship existed between the abundance of snails and the area covered by rock in squared meters. Qualitative, systematic, field sampling at three sites (Pine Point, Grapevine Point, and Lakeside) in Douglas Lake, Cheboygan County, Michigan, revealed average snails counts of 2.9, 8.2, and 8.9 respectively per sampled quadrat. Averages of the area covered by rock per quadrat were 0.051, 0.458, and 0.451 respectively. A linear relationship existed at each site, but the predictive power of the relationship was weak due to small r2 values (0.36, 0.398, and 0.243 respectively). In the laboratory, two aquaria were set up to investigate Elimia livescens' characteristic distribution. We expected no preference in substrate among sand, ""plain"" marl, rocks covered in marl, and scrubbed rocks. E. livescens did show a substrate preference with the highest counts of snails on the plain marl. This suggested that food availability was a factor influencing Elimia livescens' distribution and abundance.