What is a primary consequence of eutrophication?

The primary consequence of eutrophication is the excessive growth of algae, often referred to as algal blooms. This phenomenon occurs when water bodies receive an overload of nutrients, primarily nitrogen and phosphorus, which are commonly found in fertilizers and wastewater. As the algae proliferate, they can cover the surface of the water, blocking sunlight and disrupting the normal photosynthesis of aquatic plants.

When these algae die and decompose, the process of decomposition consumes significant amounts of dissolved oxygen in the water, leading to hypoxic conditions or even anoxic conditions where oxygen is severely depleted. This oxygen depletion can harm or kill fish and other aquatic organisms that depend on oxygen for survival, creating dead zones where life is unsustainable. This series of events highlights why excessive growth of algae leading to oxygen depletion is considered a primary consequence of eutrophication, impacting the health of aquatic ecosystems and water quality profoundly.