Why is the runoff from fertilized agricultural fields, even if free of pesticides, often harmful to the ecosystems of temperate lakes?
A) Fertilizer compounds create large hydrothermal vent communities that kill lake organisms.
B) The runoff causes heavy growth of algae, which eventually die and decompose, causing oxygen depletion.
C) Runoff water pools at the lake's bottom, where the fertilizer compounds react with materials in the sediment to form toxic substances.
D) The runoff is acid, and acidification kills key lake organisms.

Question

Quizplus · Accepted Answer

The runoff from fertilized agricultural fields contains high levels of nutrients (such as nitrogen and phosphorus) that can lead to eutrophication, which is an overgrowth of algae in the lake. As the algae eventually die and decompose, they consume oxygen from the water, leading to oxygen depletion that harms aquatic organisms.

Why Is the Runoff from Fertilized Agricultural Fields, Even If