Society for Freshwater Science Annual Meeting 2012
Zebra mussels first invaded the Great Lakes basin in the 1980s, most likely from ballast water from overseas ships. A single zebra mussel can process anywhere from 1 to <5 liters per day, which can cause cascades in many food webs. Zebra mussels were discovered in the Muskegon River, MI in 2000, leading to changes in the aquatic fauna. This study is investigating if differing zebra mussel densities affect macroinvertebrate composition and density in the Muskegon River. Thirteen 0.25 x 0.25 m<sup>2</sup> substrate samples were collected from the same riffle. Zebra mussel density varied across the riffle, but the habitat and flow remained approximately the same. Preliminary data suggests that there are some shifts in abundance and types of macroinvertebrates in relation to different densities of zebra mussels. For example, flatworms and simulids seem to have a significant positive trend with increasing zebra mussel densities. Chironomids were the most abundant insect taxon; however their density did not vary with zebra mussel density.