The Online Encyclopedia and Dictionary








Phytoplankton refers to the algal component of the plankton that drifts in the water column. The name comes from the Greek terms, πλαγκτoν, meaning "wanderer" or "drifter", and phyton or "plant". Phytoplankton, like other plants, obtain energy through the process of photosynthesis, and so live in the well-lit surface layer (termed the euphotic zone) of an ocean, sea, or lake. Their cumulative energy fixation in carbon compounds (primary production) is the basis for the vast majority of oceanic (see chemosynthesis) and some freshwater food chains. One of the most remarkable and direct food-chains is that of phytoplankton fed on by krill fed on by certain whales.

Phytoplankton produce approximately 98% of the atmospheric oxygen. Phytoplankton also release significant amounts of dimethyl sulfide (DMS) into the atmosphere which is converted to sulfate and acts as cloud condensation nuclei.

 in the Baltic Sea (July 3, 2001) seen from space
Phytoplankton bloom in the Baltic Sea (July 3, 2001) seen from space

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Last updated: 06-02-2005 03:34:57
Last updated: 09-12-2005 02:39:13