What is the process called that leads to the depletion of oxygen in a body of water?

The process that leads to the depletion of oxygen in a body of water is known as eutrophication. This phenomenon typically occurs when excess nutrients, particularly nitrogen and phosphorus, enter a water body, often as a result of runoff from agricultural land, wastewater discharge, or fertilizers.

As these nutrients accumulate, they can cause an overgrowth of algae, known as algal blooms. While initially beneficial in terms of food supply for aquatic organisms, these blooms can lead to serious ecological consequences. When the algae die, they decompose, a process that requires oxygen. As decomposers break down the organic matter, oxygen levels in the water are significantly reduced, leading to hypoxic or anoxic conditions—zones where there is insufficient oxygen for most aquatic life. This depletion can result in the death of fish and other organisms that rely on oxygen in the water.

Understanding eutrophication is crucial because it highlights the interconnectedness of land use practices and water quality, illustrating how human activities can disrupt aquatic ecosystems.