It can be defined as the lighted surface waters in the area where the lake bottom is too deep and unlit to support rooted aquatic plants. This area is occupied by a variety of phytoplankton, consisting of algae and cyanobacteria, as well as zooplankton, small crustaceans, and fish. Most photosynthesis takes place in this part of the lake.

See also

• Littoral zone
• Profundal zone
• Benthic zone
• Lake stratification