SECTION 12 



AGE SPECIFICS OF SENSITIVITY AND RESISTANCE OF FISH TO ORGANIC 



AND INORGANIC POISONS 



V.I. Lukyanenko^ 



The continually increasing interest of researchers in the age aspects of 

 toxicoresistance of fish (Mironov 1972; Kuhnbold 1972; Eisler 1972; Mitrovic 

 1972; Shmalgauzen 1973; Samylin 1974; Waldiehuk 1974; Danilchenko 1975; 

 Dethlefsen 1975; Patin 1977, etc.) results from many factors, two of which 

 are particularly interesting. 



1. The first is the need to understand the paths of direct toxic 

 influence of various substances entering the water on ichthyo- 

 fauna and, in the final analysis, on the productivity of the 

 reservoir. As we know, toxic substances affect all stages of 

 the life cycle of fish: from fertilization of eggs to sexually 

 mature individuals. However, from the ecologic standpoint, the 

 early stages of ontogenesis of fish (embryonal and immediate 

 postembryonal) are most vulnerable from the standpoint of the 

 toxic factor, since they cannot actively migrate and avoid pol- 

 luted water. It follows from this that the reaction of a popu- 

 lation of fish to chemical pollution will be determined by the 

 effect of the toxic factor on these early stages of ontogenesis 

 if they are less resistant than mature fish. 



2. The second factor determining the activation of research in the 

 area of the age factor in ichthyotoxicology is the search for 

 the most vulnerable stage in individual development of various 

 species of fish, which should be used as the test object in the 

 determination of the basic parameters of toxicity of various 

 groups of substances and subsequent determination of maximum per- 

 missible concentrations (MPC) for these substances. It is quite 

 understandable that the least resistant stages of ontogenesis 

 development of fish are of primary interest for those involved 



in development of the problem of biologic testing of the quality 

 of natural and waste waters. 



The possible influence of pollution on larvae and fry was first men- 

 tioned in the last century. For example, the great Russian ichthyologist. 



1 Institute of Biology of Inland Waters, Academy of Sciences, Borok, Nekouz, 

 Jaroslavl, 152742, USSR. 



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