Ecological response to Eurasian watermilfoil management in a Lake Superior Coastal Waterway

Document Type

Conference Proceeding

Publication Date



Eurasian watermilfoil (Myriophyllum spicatum, EWM), is a prolific invasive plant in North America. Populations of EWM have recently been established in coastal waterways of the Upper Great Lakes, where cold water temperatures and intense circulation patterns present a unique management challenge. Management of EWM is further complicated by its ability to hybridize with native northern watermilfoil (M. sibiricum) producing a community of watermilfoil with varying resistance and susceptibility to management activities. The goal of our study is to conduct a multi-faceted control program to identify the best management practices for arresting the growth and spread of EWM and its hybrids in the Upper Great Lakes via a multi-year treatment and monitoring program in the Keweenaw Waterway, Michigan. Year 1 studies of herbicide treatments show a significant decrease in EWM biomass 6 weeks after herbicide treatment, but an increase in dominance by watermilfoil hybrids. There were no changes in total biomass of non-target macrophytes or phytoplankton after treatment. In year 2, we will explore the efficacy and logistics of supplementing herbicide-based approaches with non-chemical control measures to improve management of EWM and its hybrids, with the ultimate goal of creating more cost-and time-effective treatment option.

Publication Title

58th Annual Conference on Great Lakes Research