We include this principle in hydrobiologic analysis because water quality is 

 formed by aquatic organisms. What is the required quality of drinking 

 water? In accordance with State Standard GOST 2874-73, water should be 

 transparent, colorless and odorless, pleasant to taste, should contain no 

 pathogenic organisms or toxic substances above the established MPC. 



In analyzing water in accordance with the third principle, we find at 

 times that water has long-term after-effects on aquatic organisms. They are 

 manifested as changes in fertility, time of maturation, decreased dimensions 

 of progeny and other deviations from characteristic parameters for the 

 species. Determination of all of these problems forces medical and veteri- 

 nary workers to ask the question of possible equivalent or similar in- 

 fluences on man and domestic animals using the same water for drinking pur- 

 poses. 



Summing up what we have said, it must be noted that evaluation of the 

 quality of water in reservoirs from a broad hydrobiologic standpoint more 

 reliably characterizes quality than other existing approaches. Chemical, 

 physical and bacteriologic analyses cannot completely describe the quality 

 of surface water today. The proposed hydrobiologic principles will help in 

 developing a better scientific foundation for standardization of the quality 

 of water of surface reservoirs. These principles are oriented toward devel- 

 oping standards for water quality in various regions and types of reservoirs 

 used for fishing and drinking purposes. 



The principles which we have set forth for estimation of normal and 

 pathologic states of bodies of water suffering from chemical pollution are 

 not new principles. They have been used and considered in the development 

 of criteria for water quality. What is new is that the principles formu- 

 lated are presented as a system for determination of the suitability (nor- 

 mality) or unsuitability (abnormality) of an aquatic ecosystem for the most 

 demanding water users. These principles can serve as a basis for develop- 

 ment of measures for standardization of water quality in reservoirs. 



The principles formulated should assist in the development of standards 

 for aquatic ecosystems based on the requirements of man's economic activity 

 and life support. The criterion of the ecologic norm of a given reservoir 

 might be the completeness with which the second, third and fourth principles 

 are fulfilled. If these principles are excluded, evaluation of an aquatic 

 ecosystem is senseless. 



Under all conditions, man is the main standard for evaluation of the 

 normality or abnormality of a body of water. The quality of water is be- 

 coming increasingly important for him. Therefore, evaluation of an aquatic 

 ecosystem occurs primarily along the line of quality evaluation. It is not 

 simply the number and variety of species, but rather useful species and 

 their population and productivity; not simply the stability of the system, 

 but rather the stability of the required quality of the system. Any eco- 

 system with time will reach stability given the surrounding conditions and 

 becomes stable. An aquatic ecosystem is stable both with polysaprobic 

 pollution, and with ol igosaprobic pollution. In either case, it is stable, 

 but the stability of the various qualities of water have different effects 



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