What type of pollution do excess nutrients primarily contribute to in aquatic systems?

Excess nutrients primarily lead to nutrient pollution in aquatic systems. This type of pollution is characterized by an overload of nutrients, particularly nitrogen and phosphorus, which can come from sources such as agricultural runoff, wastewater discharge, and industrial processes.

When nutrient levels increase excessively in water bodies, they can stimulate algal blooms, leading to a cascade of ecological consequences. These blooms can deplete dissolved oxygen levels as they die and decompose, resulting in hypoxic conditions that are harmful to aquatic life. The elevated nutrients effectively alter the balance of ecosystems, disrupt food webs, and degrade water quality, thus validating the classification of this phenomenon as nutrient pollution.

In contrast, thermal pollution relates to changes in water temperature, organic pollution encompasses the introduction of organic matter, and biological pollution involves the introduction of non-native species or pathogens, each associated with different ecological impacts. Nutrient pollution, however, specifically addresses the issues arising from excess nutrient enrichment, making it the most accurate choice in this context.