ABSTRACT
ABSTRACT A rapid increase in population and growth of industry and agriculature in the Lake Erie basin during 1920 to 1960 lead to dramatic increase in inputs of organic wastes and nutrients, especially in the western basin of the lake. By 1970 about half of the phosphorus loading was derived from detergents. Nutrient loading to Lake Erie was high and the western basin, which received about 74% of the total phosphorus load to the lake, was regarded as highly eutrophic. The western basin had phytoplankton biomass and taxa that were characteristic of eutrophic waters, with higher concentrations of chlorophyll a, higher primary production, and assimilation number. All eutrophic areas in Lake Erie with submerged rocky substrates promoted a profuse growth of filamentous algae, especially Cladophora. This affected water intakes; drinking water supplies had the taste of rotting vegetation. Stench arising from decomposing Cladophora affected tourism and fishing. Beaches were deserted and thus eutrophication caused a massive economic loss. Microbial decomposition of large quantities of dead algae and other organisms
lead to hypoxic and anoxic conditions in the hypolmmion during lake stratification. Whereas only 3% of hypolommion in the central basis was anoxic during the summer of 1930, the value had increased to 93.7% by 1973. Under anoxic conditions phosphorus adsorbed on to sediment is released back into water and after the fall overturn and mixing of waters it promotes algal blooms. Anoxic conditions in hypolinnetic water eliminated benthic organisms as well and some highly valued commerical and sport fish.
