What does the term 'eutrophication' refer to?

The term 'eutrophication' specifically refers to the enrichment of water bodies with nutrients, particularly nitrogen and phosphorus. This process often occurs due to runoff from agricultural fields, urban areas, or wastewater discharge, where excess nutrients enter the water.

As nutrients accumulate, they can stimulate excessive growth of algae, leading to algal blooms. While some algae are beneficial, an overabundance can create a host of problems for aquatic ecosystems. These blooms can block sunlight from reaching underwater plants, disrupting photosynthesis, and result in a subsequent die-off of algae that depletes oxygen levels in the water as decomposers break down the organic matter. This oxygen depletion can lead to further environmental stress on aquatic organisms, which can result in "dead zones" where most marine life cannot survive.

Understanding eutrophication is crucial for water management and conservation efforts, as it highlights the importance of nutrient regulation to maintain ecological balance in aquatic environments. Thus, the correct answer emphasizes the critical concept of nutrient enrichment as the defining characteristic of eutrophication.