Areas with hypoxia are known as __ zones

The answer is : dead zones.

Dead zone.

Explanation:

Hypoxia may be defined as the condition of the reduced level of oxygen in the environment. The hypoxia condition of the sea may occur due to naturally or artificially.

The hypoxia area are commonly known as dead zones. This area leads to the death of most of the marine organism due to the deficiency of the oxygen. Excess nutrients flow in the river causes the more chances of the development of the dead zones.

Thus, the answer is dead zones.