What is eutrophication in freshwater systems?

Eutrophication in freshwater systems refers specifically to the process of nutrient enrichment, particularly with nitrogen and phosphorus, which leads to excessive growth of aquatic plants, especially algae. This phenomenon occurs when nutrients from various sources, such as agricultural runoff, sewage, and industrial waste, enter water bodies.

As nutrient levels increase, they promote algal blooms, which can cover the surface of the water, blocking sunlight and disrupting the natural ecosystem. When these algae die and decompose, it can result in decreased oxygen levels in the water, creating hypoxic conditions that threaten fish and other aquatic life. This cycle not only leads to unsightly water conditions but also negatively impacts biodiversity and can result in the death of fish and other organisms, showcasing how eutrophication can cascade through an ecosystem.

Other choices, while they may be related to issues in freshwater systems, do not specifically define eutrophication. The focus of eutrophication is on nutrient enrichment and its direct effects on plant growth and ecosystem balance.