aphotic zone (bathypelagic zone) The region of a lake or sea where no light penetrates; it is situated beneath the euphotic zone. The aphotic zone contains no algae or phytoplankton, and its inhabitants are exclusively carnivorous animals or organisms that feed on sediment or detritus, all reliant on energy inputs from the euphotic zone. It extends downwards from a depth of about 1000 m, or less in turbid waters, and includes the abyssal zone.

aphotic zone(disphotic zone) A deep-water area of marine ecosystems below the depth of effective light penetration (the compensation level), analogous to the profundal zone in freshwater ecosystems.

aphotic zone (disphotic zone) A deep-water area of marine ecosystems below the depth of effective light penetration (the compensation level), analogous to the pro-fundal zone in freshwater ecosystems.