Aquatic Nuisance Species in the Great Lakes and Mississippi River Basin—A Risk Assessment in Support of GLMRIS

The U.S. Army Corps of Engineers is conducting the Great Lakes and Mississippi River Interbasin Study to identify the highest risk aquatic nuisance species currently established in either the Mississippi River Basin or the Great Lakes Basin and prevent their movement into a new basin. The Great Lakes and Mississippi River Interbasin Study focuses specifically on aquatic nuisance species movement through the Chicago Area Waterway System, a multi-use waterway connecting the two basins. In support of Great Lakes and Mississippi River Interbasin Study, we conducted a qualitative risk assessment for 33 aquatic nuisance species over a 50-year period of analysis based on the probability of aquatic nuisance species establishing in a new basin and the environmental, economic, and sociopolitical consequences of their establishment. Probability of establishment and consequences of establishment were assigned qualitative ratings of high, medium, or low after considering the species’ current location, mobility, habitat suitability, and impacts in previously invaded systems. The establishment and consequence ratings were then combined into an overall risk rating. Seven species were characterized as posing a medium risk and two species as posing a high risk to the Mississippi River Basin. Three species were characterized as posing a medium risk to the Great Lakes Basin, but no high-risk species were identified for this basin. Risk increased over time for some aquatic nuisance species based on the time frame in which these species were considered likely to establish in the new basin. Both species traits and the need to balance multiple uses of the Chicago Area Waterway System must be considered when identifying control measures to prevent aquatic nuisance species movement between the two basins.