What causes a death zone in the gulf of Mexico?

When fertilizers, manure and other sources of nitrogen and phosphorus enter waterways, they stimulate the growth of algae. This leads to an overgrowth of algae, known as an algae bloom. As the algae die and decompose, they use up oxygen in the water, creating a 'dead zone' where oxygen levels are too low for most marine organisms to survive.

The Gulf of Mexico's dead zone is one of the largest in the world, covering an area of approximately 16,000 square kilometres. It is primarily caused by nitrogen runoff from the Mississippi River, which drains a vast agricultural watershed in the Midwest. The heavy use of nitrogen fertilizers and manure in this region contributes significantly to the problem.

Efforts are underway to address this issue, such as reducing nutrient pollution and improving agricultural practices, but it remains a significant environmental concern.