What is a "dead zone" in aquatic environments?

A "dead zone" in aquatic environments is characterized by low levels of dissolved oxygen, which makes it difficult or impossible for aquatic life to survive. These areas often occur as a result of nutrient pollution, where excess nutrients, particularly nitrogen and phosphorus, lead to algal blooms. When these algae die and decompose, the decomposition process consumes significant amounts of oxygen in the water, creating hypoxic (low oxygen) conditions. In such environments, fish, crabs, and other marine organisms either die or are forced to migrate to more hospitable conditions, leading to reduced biodiversity and disruption of the aquatic ecosystem. This phenomenon highlights the serious impact of nutrient runoff and pollution on marine habitats.