What human activities contribute to the creation of dead zone?

Human activities such as agricultural runoff, industrial discharges, and urban wastewater contribute significantly to the creation of dead zones in aquatic ecosystems. The excessive use of fertilizers leads to nutrient pollution, particularly nitrogen and phosphorus, which can cause algal blooms. When these algae die and decompose, the process depletes oxygen levels in the water, resulting in hypoxic conditions that are detrimental to marine life. Additionally, coastal development can exacerbate these issues by altering water flow and increasing nutrient inputs.