What impact does eutrophication have on aquatic life?

Eutrophication is a process characterized by the excessive growth of algae in water bodies, often due to increased nutrient input, such as nitrogen and phosphorus from agricultural runoff, sewage, and fertilizers. This rapid growth of algae can create several negative effects on aquatic ecosystems. When the algae die, they decompose, a process that consumes a significant amount of dissolved oxygen in the water. As the oxygen levels decrease, it can lead to hypoxic conditions, where oxygen availability becomes insufficient for fish and other aquatic organisms to survive.

Many aquatic species, especially fish and invertebrates, depend on dissolved oxygen for respiration. Reduced oxygen levels can result in stress, diminished reproductive rates, and even fish kills. This phenomenon contributes to the decline in biodiversity and can severely disrupt the balance of aquatic ecosystems, leading to what is known as dead zones—areas where most aquatic life cannot survive due to lack of oxygen.

In contrast, the other options do not accurately represent the consequences of eutrophication. Enhanced fish reproductive rates and stable ecosystems do not align with the realities of eutrophication, while filtering pollutants from the water overlooks the negative consequences such as oxygen depletion and algal blooms.