What negative impact can excess nutrients have on water bodies?

Excess nutrients, particularly nitrogen and phosphorus, can lead to significant ecological issues in water bodies through a process known as eutrophication. When these nutrients enter water bodies, often from agricultural runoff, wastewater discharge, or other sources, they promote the excessive growth of algae, commonly referred to as algal blooms. These blooms can cover the surface of the water, blocking sunlight and disrupting the growth of aquatic plants.

As the algae die off, their decomposition consumes a large amount of dissolved oxygen in the water. This depletion of oxygen can create hypoxic or anoxic conditions, severely affecting aquatic life. Species such as fish and invertebrates may struggle to survive in low-oxygen environments, leading to die-offs and a decrease in biodiversity. Furthermore, some algal blooms can produce toxins that are harmful to both aquatic organisms and humans, further exacerbating the negative impacts on water quality and ecosystem health.

In contrast, other options such as improving water quality, enhancing aquatic biodiversity, or reducing water temperature do not align with the consequences of nutrient overload, as they fail to reflect the detrimental effects of eutrophication and the resultant ecological imbalance.