Aphotic zone
The aphotic zone is the depth of the ocean that is not exposed to sunlight. The depth of the aphotic zone can be greatly affected by such things as turbidity and the season of the year. The aphotic zone generally underlies the photic zone, which is that portion of the ocean directly affected by sunlight. Organisms in the aphotic zone directly or indirectly depend on smaller producers, such as plankton, from the photic zone.