What is the primary consequence of eutrophication in water systems?

Eutrophication is a process that occurs when excessive nutrients, particularly nitrogen and phosphorus, accumulate in aquatic systems, usually as a result of agricultural runoff, wastewater discharge, or other sources of nutrient pollution. The primary consequence of this nutrient surplus is excessive algae growth, often referred to as algal blooms.

These blooms can significantly alter the aquatic ecosystem. They cover the surface of the water, blocking sunlight from penetrating, which affects the photosynthesis of underwater plants and disrupts the balance of the ecosystem. As the algae die and decompose, the decomposition process consumes dissolved oxygen in the water, leading to hypoxic or anoxic conditions. This can result in fish kills and loss of aquatic life, further destabilizing the ecosystem.

While it is possible for nitrogen and phosphorus enrichment to initially lead to increased fish populations in some scenarios due to more nutrients supporting more plant growth, the long-term effects of eutrophication are detrimental, leading to decreased water clarity and overall health of the aquatic ecosystem. Enhanced biodiversity is rarely a consequence of eutrophication; instead, it often leads to dominance of a few species, particularly harmful algae, which can choke out other forms of life.