To the left, you see a graph of the concentration
of oxygen (O2) dissolved in the ocean.
Note how the shape of the curve showing the concentration of dissolved oxygen
is nearly the reverse of those associated with the concentration of limiting
Oxygen is relatively high in the surface
waters where it is produced through photosynthesis by marine algae
(phytoplankton) and absorbed from the atmosphere. The oxygen
minimum zone, between 200 meters (m) and 600 meters (m), contains the least
amount of oxygen in the sea, since little or no oxygen can be produced here
(below the euphotic zone) and oxygen is stripped from the ocean by
respiration and the decomposition of organic material that sinks downward
from the surface waters.
The oxygen-rich deep waters, North Atlantic
Deep Water (NADW) and Antarctic Bottom Water (AABW), acquire high
amounts of oxygen during formation in the surface waters prior to sinking to
the deep sea.