Why is too much algal growth, as a result of eutrophication, a problem in a freshwater system?

Question

What will be an ideal response?

Answer 1

Algae that grow too rapidly can cover the water's surface, harming the deeper-water plants that depend on sunlight for survival. As algae die off, they provide food for decomposing bacteria. Because decomposition of organic matter requires oxygen, the increased bacterial activity drives down levels of dissolved oxygen. These levels can drop too low to support fish and shellfish, leading to dramatic changes in aquatic ecosystems and loss of biodiversity. Also, the increasing turbidity and anaerobic metabolism have a destructive effect on coastal marine communities, especially coral reefs, making these eutrophic systems unappealing to fishermen and recreational users.