Evaluation of invasions and declines of submersed macrophytes for the upper great lakes region

Abstract

In the upper Great Lakes region, Myriophyttum spicatum, Elodea canadensis, Potamogeton crispus, and Ceratophyllum demersum are the most significant nuisances. M. spicatum and P. crispus have generally invaded lakes with hard water, abundant nutrients, and a history of disturbance or heavy human use. M. spicatum has declined in some Wisconsin lakes, but not in all that it invaded. The reason for declines was never satisfactorily explained. Following its decline in Madison, WI, lakes, the M. spicatum population never regained its former predominance. There are no long-term data to determine whether populations of native macrophyte species are expanding, stable, or declining on a regional basis, although diversity of the aquatic plant communities of Madison-area lakes has declined over the last 80 years. Most aquatic plant management in the upper Great Lakes region involves controlling nuisance species. Herbicides and mechanical harvesting are the primary means of management, although drawdowns, bottom blanketing, and other methods are also used. Minnesota and Wisconsin have public education programs intended to promote early detection of nuisance species and to minimize their spread. In Wisconsin, reintroduction of aquatic vegetation to lakes is being attempted on an experimental basis for a variety of reasons, including fish and wildlife habitat and water-quality improvement. © 1994 Taylor and Francis Group, LLC.