Agricultural Runoff and Fertilisers

Agricultural runoff, primarily containing nitrogen and phosphorus from fertilizers, is a significant cause of ocean pollution and contributes to the formation of hypoxic zones, commonly known as 'dead zones'. There are over 500 such zones identified worldwide. These areas are characterized by extremely low oxygen levels, making it impossible for most marine life to survive. A notable example is the dead zone in the Gulf of Mexico, which has been observed to cover an area of approximately 15,000 square kilometers. The excess nutrients from runoff trigger massive algal blooms. When these algae die and decompose, they consume vast amounts of oxygen, leading to the collapse of local ecosystems and causing widespread mortality among fish and coral populations.