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Photic Zone

Research In The Photic Zone

Research in the photic zone is focused on three main priorities: eutrophication of water bodies, fundamental food web research, and the understanding of nutrient movement and cycling. Eutrophication is the enrichment of water bodies through the addition of nutrients, often leading to excessive phytoplankton growth. Eutrophication is a well understood process, but it remains as a serious problem in much of the world.

Another important area is research into basic food webs. Many things are still to be discovered regarding the relative roles of species within aquatic food webs. The recent closure of the fisheries off eastern Canada exemplifies the importance of basic understanding of food webs in these productive photic zones.

A third area of research within the photic zone involves nutrient movements and cycling within water bodies. Especially in oceans the movements of particles and nutrients by water currents are not well understood. We are just beginning to understand the connections among wind, ocean currents, and global weather patterns. All life ultimately depends on the continued productivity of the photic zones of the world, and we need to work harder to understand the physical, chemical, and biological nature of these zones.

See also Ocean zones.



Barnes, R. S. K., and K. H. Mann, eds. Fundamentals of Aquatic Ecology. 2nd ed. Cambridge, MA: Blackwell Scientific Publications, 1991.

Begon, M., J.L. Harper, and C. R. Townsend. Ecology: Individuals, Populations and Communities. 2nd ed. Cambridge, MA: Blackwell Scientific Publications, 1990.

Cousteau, Jacques-Yves. The Ocean World of Jacques Cousteau: Window in the Sea. World Publishing Company, 1973.

Culliney, J. L. "The Fluid Forests." In The Forests of the Sea: Life and Death on the Continental Shelf. San Francisco Sierra Club Books, 1976.

Miller, G. Tyler, Jr. Environmental Science: Sustaining the Earth. 3rd ed. Belmont, CA: Wadsworth Publishing, 1986.

Jennifer LeBlanc


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Abyssal zone

—Volume of water near the bottom of the ocean where there is no sunlight, usually below 6,562 ft (2,000 m).

Compensation point

—The point at which the rate of photosynthesis just equals the rate of respiration by phytoplankton. This is the lower limit of the photic zone.


—The enrichment of natural water bodies through the addition of nutrients, usually phosphate and/or nitrate, leading to an excessive growth of phytoplankton.

Hadal zone

—The deepest layer of the ocean, below 19,686 ft (6,000 m).


—The process of converting water and carbon dioxide into carbohydrates (sugars), using solar energy as an energy source. Oxygen is released during this process.


—Microscopic plants having no or little ability to move themselves, and therefore are subject to dispersal by water movement.

Primary production

—The production of organic matter (biomass) by green plants through photosynthesis.

Profundal zone

—Zone below the photic zone where there is some light but not enough to support photosynthesis.

Additional topics

Science EncyclopediaScience & Philosophy: Philosophy of Mind - Early Ideas to Planck lengthPhotic Zone - Other Layers In Oceans And Lakes, The Importance Of Nutrients And Light In Photic Zone, Research In The Photic Zone