The ocean water column is made up of 5 zones. The sunlight zone, the twilight zone, the midnight zone, the abyss and the trenches. This zone extends from the surface down to about 700 feet.

Photo Credit: NASA Oxygen-starved ocean “dead zones,” where fish and animals cannot survive, have been expanding in the open ocean and coastal waters for several decades as a result of human ...

In the last 50 years, oxygen-deficient zones in the open ocean have increased. Scientists have attributed this development to rising global temperatures: Less oxygen dissolves in warmer water, and the ...