About Indicator Species

[EwA]

Indicator species (definition): An organism—often a microorganism or a plant—that serves as a measure of the environmental conditions that exist in a given locale. For example, greasewood indicates saline soil; mosses often indicate acid soil. Tubifex worms indicate oxygen-poor and stagnant water unfit to drink. The presence of certain species of plants suggests how well other species might grow in the same place. (Britannica)

The presence and/or abundance of such species may be used to indicate favorable or unfavorable ecological conditions that may be difficult or costly to detect by other means. For example, aquatic plants can be used as indicators of overall water quality. 

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