3. Survival, growth, reproduction, fertility, and quality of the 

 aquatic organisms' progeny. 



All the enumerated criteria most completely characterize the ecological 

 and toxicological situation in the water body and are widely used to deter- 

 mine the maximum permissible concentration of artificial substances. 



In view of the necessity to develop express methods which would help to 

 detect the aquatic organism-metabolism links changing in the first instance 

 under the influence of toxicants, a study of the biochemical mechanisms of 

 toxicant effect on the aquatic organisms has been planned. There are some 

 data affirming that the effect of many toxicants is the result of effects 

 on enzyme processes in the aquatic organism. For example, an anticholine- 

 sterase effect of phosphorus organic compounds on fish has been ascertained 

 (Metelev, et al., 1971). 



The investigation carried out in our Institute (Malyarevskaya, Birger, 

 Arsan, Solomatina, 1973) give an idea of the threshold and biologically dan- 

 gerous concentrations of biological toxicants for fish (e.g., effect of 

 blue-green algae Microcystic aeruginosa Kutz. emend. Elenk). The experi- 

 ments were carried out from 1964 to 1974 in laboratories and in water 

 bodies exposed to a heavy "bloom" caused by mass development of blue-green 

 algae. Effects of various blue-green algae concentrations on fish (pike 

 perch Lucioperca lucioperca L . , perch Perca f luviatilis L . , i de Leuciscus 

 idus L . , cruc i an Carassius carassius L . , and Hypophthalmichtys molitrix 

 Val . ) were studied. 



In long-term experiments, small quantities of algae were applied (0.03- 

 0.30 g/liter). Since the fish did not die, they were conditionally named 

 "nonlethal". When more considerable concentrations (0.6 - 5.0 g/liter) 

 were used in acute experiments, the fish died within a period of 6-64 

 hours, depending on the fish species and algae concentration and condition 

 (living, decaying). Such algae concentrations were called "lethal". 



The biochemical composition of fish (content in their bodies of dry or- 

 ganic substances, ashes, protein and its amino acid composition, lipids, 

 vitamins Bi, B 2 and enzyme activity of thiaminase, cholinesterase, trans- 

 aminse and content of nicotinamide coenzymes) and also the fish metabolism 

 (interchange of gases and nitrogen exchange) have been investigated and the 

 effect of various algae concentrations on them has been ascertained. 



The effect of blue-green algae on fish is conditioned by the complex of 

 biotic and abiotic factors which includes the effects of metabolism pro- 

 ducts, algae decomposition, and changes in the hydrochemical indices in the 

 environment. 



Non-lethal algae concentrations (0.03-0.30 g/liter) do not cause the 

 death of fish, but if a fish inhabits waters characterized by such a 

 quantity of algae (especially 0.3 g/liter), it results in determinable 

 changes in the metabolism, i.e., suppression of plastic processes and 

 intensification of energetic processes. The growth of dry and organic sub- 



107 



