Introduction Under natural conditions, all organic activities are interrelated in one way or another. Vital processes of organisms are inter-correlated as well as intercondition also with respect to the production of organic matter by aquatic populations Phytoplankton production depends primarily upon such environmental conditions as nutrients, light and temperature(STEEMANN NIELSEN and JENSEN, 1957; SOROKN, 1958). However, not only abiotic factors, also some biotic ones, influence primary production ut(RYTHER, 1954; TEN and FINENEo, 1969). Among the biotic factors, processes of elimination grazing of one population upon another and natural mortality re most important(CUSHING, 1958)