Lake Michigan is being invaded by a predator new to the Nearctic. Bythotrephes cederstroemii, was first found in the Laurentian Great Lakes in December, 1984. By August 1986, the species had spread to Southern Lake Michigan, and was doubling in abundance every 10 days. Bythotrephes is invading aggressively, particularly in the offshore region, but is so far avoiding habitats occupied by glaciomarine relict species. As an invading plankton species joining an existing community, it represents a rare opportunity to study manipulation of a food web at the middle trophic level. Judging from its persistence and success in deep European lakes, Bythotrephes will probably become a permanent member of zooplankton communities in the Nearctic. This proposal seeks to study the trophic dynamics of this community-level perturbation across the physical and ecological gradients between inshore and offshore regions.
