Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Non-native amphipod, Apocorophium lacustre (Vanhoffen, 1911), in the Illinois River and Chicago area waterway system.

Abstract

Apocorophium lacustre (Vanhoffen, 1911) is a recent colonizer of freshwater ecosystems in the United States of America and Europe. This species is native primarily to estuarine environments on both sides of the North Atlantic, but in the US it has been established in the Gulf of Mexico since at least 1982 and more recently in the Mississippi River Basin. In 2005 it was found in the Dresden Island Pool of the Upper Illinois River, placing it within 100 river kilometers of Lake Michigan, and it is considered a high risk for continuing its spread into the Laurentian Great Lakes. During summer 2015 we conducted what we believe is the only sampling for this species to have taken place upstream of the Dresden Island Pool since 2005. We sampled at 25 sites from the Dresden Island Pool upstream to Lake Michigan, including six Lake Michigan harbors. A. lacustre was found at a single site in the Dresden Island Pool, indicating that the species has not spread over the last decade. This result could occur because of a physical or chemical barrier to further movement, or because our sampling was not sufficient to locate the population. Further sampling, and tests of A. lacustre tolerance to water from different sources, will be required to determine if spread has truly stopped, and if so, the reason for this.