biological indicators, organisms whose presence, numbers, or intensity of development serves as an indication of some natural processes or environmental conditions—for example, the presence or absence of certain substances (including those of practical importance).
Masses of piscivorous marine birds serve as bioindicators of the location of schools of fish. The probability of successful fishing for herring and some other fishes dwelling in deep water can be judged from the plankton composition. The presence of many benthic and planktonic organisms is indicative of the origin of water masses—for example, Atlantic waters in the polar basin. Similarly, the composition of diatoms on floating ice indicates the origin and routes of drift of such ice. The quantity of these algae (Cocconeis ceticola) on the skin of whales tells how long the whales have been in antarctic waters.
Bioindicators are widely used to appraise water purity. The suitability of water for drinking purposes and the efficiency with which treatment facilities are operating can be judged from the composition of the water flora and fauna. Various methods exist for analyzing the degree of pollution (saprobic quality) of water from the indicator organisms.
Soil quality can be roughly assessed by means of so-called indicator plants. In the USSR, biological indication of soils based on differences in the soil fauna was suggested by M. S. Giliarov in 1949, and biological indication based on microbiological characteristics was suggested by E. N. Mishustin in 1950. Geologists use indicator plants in prospecting; it is possible to obtain a rough idea of the presence of fuel gases and petroleum in the interior of the earth from the presence of certain groups of microorganisms in the surface layers of the earth’s crust (V. S. Butkevich and others).
Animals, plants, and microorganisms are used in space research as bioindicators to determine the effect of spaceflight factors on living organisms.
Microorganisms are widely used as bioindicators in analytical work (determination of vitamins, antibiotics, amino acids, and other substances).
IA. A. BIRSHTEINAND V. P. DADYKIN