Degradation of Laurentian Great Lakes Biota--Causes and Effects Through 1970

Pollutants from direct and indirect human activities have resulted in alterations of Great Lakes biota, and many of these alterations have had negative economic impacts. Lake Erie, with the least volume of water, and with the largest human population on surrounding land, suffered the most dramatic changes, particularly as a consequence of phosphorus and mercury pollution. Accelerated eutrophication altered the quantity and quality of the phytoplankton and shoreline vegetation. Declines in mayflies (Hexagenia) contributed to reductions in commercially important fish. Contamination from mercury and other toxics led to banning the marketing of several fish species. In response to these problems, governmental agencies in the United States and Canada enacted regulations to abate Great Lakes pollution.