¹Fisheries and Oceans Canada, 867 Lakeshore Road, Burlington, ON, Canada L7R 4A6
²Plankton Canada, 685 Inverary Road, Burlington, ON Canada, L7L 2L8
³Ontario Ministry of Natural Resources, 320 Milo Road, Wheatley, ON, Canada, N0P 2P0 (Retired)

Abstract

  For the past several decades, the North American Great Lakes have suffered from eutrophication. The deteriorating state of the Great Lakes alarmed both the governments of Canada and the United States resulting in the Great Lakes Water Quality Agreement, which has brought about substantial improvements in water quality. While phosphorus abatement resulted in a significant decrease in nutrients, the sudden invasions of exotic species posed a serious threat to Great Lakes food webs. Dreissena polymorpha and Dreissena bugensis, followed by other exotic species, infested Lakes Erie and Ontario causing a drastic reduction in phytoplankton biomass and increasing water clarity. This paper presents an historical perspective and a general overview of the impact of aquatic invasive species in the North American Great Lakes from the base of the food web to the fisheries. Lake Erie has been chosen as a case study to provide a detailed treatment. The expansion and growth of aquatic invasive species has been responsible for significant modifications to the structural and functional characteristics of the food webs and fisheries of the Great Lakes that has lead to serious economic consequences. Our Great Lakes experience demonstrates the significance of the impact of exotic invaders and the need to manage this serious problem on a global basis so that the integrity of food webs and fisheries throughout the world can be protected.
This paper is dedicated to Dr. Jack Vallentyne for his contributions to Great Lakes research, especially for the implementation of the ‘ecosystem approach’. These contributions were in evidence in revisions to the Great Lakes Water Quality Agreement and more currently in the management of exotic species.