Deep chlorophyll maximum

A deep chlorophyll maximum, or DCM, is a subsurface maximum in the concentration of chlorophyll in the ocean or in lakes. Throughout much of the tropical ocean, the DCM is a permanent feature. At higher latitudes, it occurs seasonally. The presence of a DCM may indicate a maximum in the abundance of phytoplankton, or it may result from the higher chlorophyll content of phytoplankton living in a darker environment.