Population Dynamics of Protozoa Associated with the Decay of organic Materials in Fresh Water

Abstract

The high intensity of decomposition in heavily polluted systems favors high individual counts of certain species of cilate Protozoa, in spite of the lack of dissolved oxygen and the presence of ammonia and other products of septic decay. Other species grow best under the particular conditions of starting re-aeration or nitrification, respectively. In general, the whole range of the self-purification process may be divided into zones which are characterized by particular associations of ciliates. The population growth of these species is regulated by (1) availability of food, for example, bacteria; (2) abiotic environmental factors, such as oxygen and products of septic decay; and (3) competition and predator-prey relations.