What can excessive nutrient runoff from agriculture lead to?

Excessive nutrient runoff from agriculture, particularly nitrogen and phosphorus, can lead to eutrophication of water bodies. This process occurs when high concentrations of nutrients enter a water body, promoting an overgrowth of algae, also known as algal blooms. While initially the presence of more nutrients might seem beneficial, the rapid growth of algae can deplete oxygen levels in the water once the algae die and decompose. This depletion can create hypoxic or anoxic conditions, which are harmful to aquatic life, leading to dead zones where fish and other organisms cannot survive.

Eutrophication can also result in altered ecosystems, diminishing biodiversity, and negatively affecting water quality and aquatic habitats. The impacts are far-reaching, affecting not only the organisms living in these aquatic environments but also the humans who rely on these bodies of water for drinking, recreation, and fishing.

In contrast to this phenomenon, options that suggest improved ecosystems, enhanced soil fertility, or reduced invasive species do not accurately describe the consequences of nutrient runoff and the resultant eutrophication process. Each of these options reflects a misunderstanding of the ecological relationships and dynamics involved in excessive nutrient loading in aquatic systems.