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photic zone

noun, Biology
the upper layer of a body of water delineated by the depth to which enough sunlight can penetrate to permit photosynthesis.
Origin of photic zone
1970-75 Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for photic zone
  • It's a beautiful thing and also a little daunting, saying goodbye to the sun as you sink deep down past the photic zone.
  • At fall overturn, the nutrients and other compounds may reenter the photic zone and stimulate algal productivity.
  • The depth of the photic zone in a given image is a factor of the sediment load, sea conditions, and image quality.
  • Virtually all marine phytoplankton are buoyant and live in the upper part of the water column called the photic zone.
  • Most planktonic diatoms are centric and are the primary nutrient producers in the photic zone.
  • Consequently, much of the lake is shallow enough that nearly the entire water column is continuously within the photic zone.
Contemporary definitions for photic zone

the upper part of a body of water that is exposed to sunlight and permits photosynthesis; also called euphotic zone


The photic zone is usually less than 100 meters in depth.'s 21st Century Lexicon
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