What is one effect of eutrophication in aquatic systems?

Eutrophication is a process that occurs when water bodies receive an excess of nutrients, particularly phosphorus and nitrogen, often from agricultural runoff or wastewater. This nutrient overload stimulates the rapid growth of algae, known as algal blooms. While the initial increase in algae can appear beneficial, the subsequent decay of this increased biomass leads to significant problems.

As algae die, they are decomposed by bacteria, a process that consumes oxygen from the water. This reduction in oxygen creates hypoxic conditions, which can be detrimental to aquatic life. Many aquatic organisms, such as fish and invertebrates, require dissolved oxygen to survive; thus, the decreased oxygen levels can lead to dead zones where these organisms cannot thrive. The result is a decline in biodiversity and the potential collapse of the aquatic ecosystem.

In contrast, the other options suggest outcomes that do not accurately reflect the effects of eutrophication. Increased diversity of species is typically not an effect of eutrophication, as the resulting hypoxic conditions often harm fish populations and other aquatic organisms. The temperature of the water may vary for reasons unrelated to eutrophication, and nutrient levels would actually increase rather than decrease due to the input that originally caused eutrophication.