Dead zones are hypoxic areas in the world's oceans and large lakes. Hypoxia occurs when dissolved oxygen concentration falls to or below 2 ml of O₂/liter. When a body of water experiences hypoxic conditions, aquatic flora and fauna begin to change behavior in order to reach sections of water with higher oxygen levels.

What causes a hypoxic zone?

Hypoxia occurs when algae and other organisms die from lack of oxygen and available nutrients. Hypoxia events often follow algal blooms. ... This lack of oxygen creates dead zones in which most aquatic species cannot survive. The Gulf of Mexico has a seasonal hypoxic zone that forms every year in late summer.

What is meant by the term hypoxic zone?

"Dead zone" is a more common term for hypoxia, which refers to a reduced level of oxygen in the water.