What is a significant consequence of eutrophication in aquatic systems?

Eutrophication is the process through which water bodies become overly enriched with nutrients, particularly nitrogen and phosphorus. This nutrient overload primarily comes from agricultural runoff, wastewater discharge, and other sources. As these nutrients accumulate in an aquatic system, they lead to excessive growth of algae, known as algal blooms. When these blooms die off, they decompose, a process that consumes significant amounts of dissolved oxygen in the water.

The consequence of this oxygen consumption is that it leads to oxygen depletion, or hypoxia, in the water. This poses a serious threat to aquatic life, particularly fish and other organisms that require oxygen for survival. As oxygen levels decline, it can result in die-offs of fish and other aerobic organisms, which in turn disrupts the entire ecosystem and can lead to a decrease in biodiversity.

While the other options might seem plausible in different contexts, they do not capture the primary and most critical outcome of eutrophication. Increased biodiversity, for instance, typically occurs in a healthy ecosystem but declines with the stress caused by hypoxia. Shallow water formation and rapid sedimentation may occur in certain scenarios but are not the most significant and immediate consequence of the nutrient over-enrichment that characterizes eutrophication.