noting or pertaining to the layer or zone of sea water that receives enough sunlight for photosynthesis to occur, varying greatly with season and latitude, from 0 to 1200 feet (0–360 m).
eu·phot·ic (yōō-fŏt'ĭk) adj. Of, relating to, or being the uppermost layer of a body of water that receives sufficient light for photosynthesis and the growth of green plants.