Saprobic Zones

SAPROBIC ZONES, zones of water bodies established on the principle of saprobity of the organisms living in them, where saprobity of an organism refers to the complex of physiological properties that determine the ability of a given organism to develop in water with a certain content of organic substances, i.e., with a greater or lesser degree of pollution. Kolkwitz and Marsson compiled a list of indicator organisms characterizing the sanitary condition of water bodies according to the degree of pollution, and established the zones of distribution of these organisms. At present, this list has been significantly supplemented by other researchers. All saprobic organisms Kolkwitz and Marsson divide into 4 main groups: 1) polysaprobic - living in very polluted waters, 2) alpha-mesosaprobic - living in less polluted waters, 3) beta-mesosaprobic - living in weakly polluted waters, and 4) oligosaprobic - living in clean waters. Depending on which of these groups of organisms predominates in a water body, a given water body or its part is attributed to a certain saprobic zone bearing the same name as the characterizing group of saprobic organisms, i.e., to the polysaprobic zone, or alpha-mesosaprobic zone, or beta-mesosaprobic zone, or oligosaprobic zone. (For characteristics of saprobic zones - see Biological method of wastewater purification.) The boundaries of saprobic zones are subject to significant fluctuations depending on many conditions: the amount of water in the water body, the nature of its movement, the quantity and quality of incoming pollutants, temperature, time of year, etc. These fluctuations are not the same in different places of the water body: surface, deep, and coastal. Therefore, when studying water bodies, saprobic zones are subdivided into abyssal (from French abyssal) - deep, bottom, littoral (from French littoral) - coastal, shore, and pelagic (pelagique) - zones of the central parts of the water body.