Impact of Aquatic Plant Management Methodologies on Eurasian Watermilfoil Populations in Southeast Wisconsin

Declines and increases in Eurasian watermilfoil populations (Myriophyllum spicatum L.) throughout North American Lakes have highlighted the need for long-term studies. Similarly, understanding the long-term implications of different aquatic plant management techniques (e.g., mechanical harvesting, chemical treatment, no management) is a crucial component of aquatic plant management. We examined the aquatic plant communities and management techniques for nine Southeast Wisconsin lakes for a period of 6 to 9 years prior to 1996 to assess the long-term population changes of Eurasian watermilfoil subjected to different management regimes. In eight of the nine lakes, the Eurasian watermilfoil populations either declined in frequency or remained constant; while in seven of the nine lakes the native aquatic plant community either increased in average number of plant species per sample location or remained constant The long-term aquatic plant community information for these nine case study lakes suggest that “typical” aquatic plant management activities does not negatively effect the lake-wide aquatic plant community; although changes, or the lack of changes, of an aquatic plant community cannot be directly attributed to management activities.