GEOLOGY

Detailed explanation-1: -A combination of physical characteristics and surrounding land use make Lake Erie the most susceptible of the Great Lakes to eutrophication (the effect of excess phosphorus).

Detailed explanation-2: -Lake Ontario, although rich in nutrients, is morphometrically oligotrophic or mesotrophic because of its large area of deep water. Lake Erie, the most productive of the lakes and the shallowest, is eutrophic.

Detailed explanation-3: -Lake Erie has a history of environmental degradation and past industrial and wastewater runoff led to eutrophication throughout the lake. Although historically once improved, eutrophication has accelerated over past decades due to human activity in the watershed and remains a serious threat.

Detailed explanation-4: -Lake Erie is heavily impacted by urban and agricultural nutrient loading. The timing and bioavailability of these nutrient inputs favour toxic cyanobacteria. High organic production exacerbates bottom hypoxia and sediment release of phosphorus, which will delay the lake’s response to nutrient management.