In addition, since each lethal concentration needs a definite period of 

 time for action, short-term effects of even considerable algal concentra- 

 tions do not always result in the fishes' death, but can change their meta- 

 bolism and that will affect in the future the species reproduction. 



A considerable effect of algal concentrations in the environment on the 

 metabolism indices of some fish species is seen in an example of blue-green 

 algae "bloom" stimuli. As a result of the investigations, threshold concen- 

 trations of algae accumulation in the environment have been determined. Ex- 

 ceeding those threshold concentrations appreciably results in negative 

 effects of algae on vital activity of fish even in an environment completely 

 deprived of other chemical pollutants. 



REFERENCES 



Braginskiy, L.P., S.L. Gusynskaya, I.M. Papchenko, A.M. Litvinova, and A.F. 

 Sysuyeva. 1965. Toxic and bactericide properties of extracts from 

 plankton blue-green algae. Vopr. Gidrobiol. Is'zd. Vses. Gidrobiol. 

 OB-VA. M. Izd. "Nauka". 



Birger, T.I., A.Ya. Malyarevskaya, and O.M. Arsan. 1973. On the etiology 

 of Gaff's (Yuksov-Sartlan) disease. Gidrobiol. Zh. 2. 



Goryunova, S.V. 1966. Formation of algae, their physiological role and 

 influence on the general regime of water bodies. Gidrobiol. Zh. 24. 



Komarovskiy, F.Ya. 1970. On several pathological changes in fish under 

 the influence of blue-green algae. Gidrobiol. Zh. Vol. VI, 2. 



Malyarevskaya, A.Ya., T.I. Birger, O.M. Arsan, and V.D. Solomatina. 1973. 

 Influence of blue-green algae on fish metabolism. "Naukova Dumka" 

 Kiev. 



Metelev, V.V. 1971. Toxicity of pesticides for fish, effect mechanism, 

 indicator methods. Ekspep. Vodn. Toksikologiya, Vol. 2. "Zinatne" 

 Riga. 



Sirenko, L.A. 1972. Physiological bases for reproduction of blue-green 

 algae in water reservoirs. "Nauka Dumka" Kiev. 



Stroganov, N.C. 1972. Scientific bases for establishing the MPC for toxic 

 substances in open water bodies. Biolog. Aspec. Scientific Bases for 

 Establishing MPC in the Water Environment and Self-Purification of Sur- 

 face Waters. 



114 



