Predicting Eurasian watermilfoil invasions in Minnesota

Eurasian watermilfoil is an invasive aquatic macrophyte that can be difficult to control once established in a lake. Identifying characteristics of lakes susceptible to Eurasian watermilfoil establishment can aid management by allowing managers to focus their education and monitoring efforts on susceptible lakes. Using linear discriminant function analysis and logistic regression to analyze known occurrences of Eurasian watermilfoil, we developed models to predict susceptible lakes in Minnesota. The most reliable predictors of Eurasian watermilfoil invasion were distance to the nearest invaded lake and duration of that invasion, indicating that transport (exposure) is an important variable. However, exposure is not a guarantee of establishment: lake size, alkalinity, Secchi depth, and lake depth were also significant predictors of invasion. Specifically, large deep lakes with moderate to high alkalinity and moderate Secchi depth were more likely to be invaded. Models predicted an additional 2,100 to more than 4,700 of Minnesota's more than 12,000 lakes could be invaded by Eurasian watermilfoil.