photic zone

American  

noun

Biology.

1. the upper layer of a body of water delineated by the depth to which enough sunlight can penetrate to permit photosynthesis.

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Etymology

Origin of photic zone

First recorded in 1970–75

Example Sentences

The region starts about 1,000 feet down — just beneath the photic zone, which gets enough sunlight to support photosynthesis and most of the sea’s plants — and descends for miles.

From New York Times

Longhurst, A. R. & Glen Harrison, W. Vertical nitrogen flux from the oceanic photic zone by diel migrant zooplankton and nekton.

From Nature

In Puget Sound, bull kelp typically reaches one to 10 meters, but can grow much longer on the coast, Mumford said.It occupies the “photic zone,” waters that are shallow enough for light to reach the sea floor.

From Washington Times

Once the Martian water grows warmer and begins to leak out of these deposits, it would seep up first to what's known as a photic zone, a think film of surface soil where warmth from the sun could allow biological activity to take place.

From Time