The method of low level luminiscence developed by a group of Moscow bio- 

 physicists enables an evaluation of the toxicity of the minimum concentra- 

 tions of toxic agents. 



In addition to the luminiscence method, differentiation of living and 

 dead algal cells may be performed with a help of dyes (0.1 percent 

 neutral red), reagents (TTX) and fluorochromes. 



Occasionally, dead and living algae may be discerned even when using 

 vital microscopy, or the dark field technique. These techniques reveal 

 tological disturbances (plasmolysis, disintegration of the chromatophore 

 and cell walls) under the action of toxicants in large filamentous algae 

 Cladophofia, Rkizoclovuum and others (Braginski, 1972; Anon., 1959). The 

 Institute of Biology of the Ukranian Academy of Sciences has proposed a 

 number of cytochemical tests which enable observation of disturbances of 

 the living activity of blue-green algae in a toxic medium. These methods 

 involve determination of permeability of cell membranes when staining 

 with nitrosine, determination of ascorbic acid content, sulphur hydryl 

 group determination, measurement of enzymatic activity of cells, and ob- 

 servation of the redox potential of test cultures (Osterov, 1968). 



Advances in understanding of the physiology of algae allow the use of 

 a whole complex of experimental methods including the celloscopic counting 

 of cells in test cultures, the determination of the chlorophylls, caro- 

 tenoids and other pigments (Anon., 1975). All these tests are important 

 since they take into account the possible harmful effect of toxicants, 

 not only upon animals, but also upon the components of primary production 

 of waters. To date, insufficient attention has been given to the primary 

 producers when ascertaining the ecological threat of chemical pollutants. 

 In this regard, of substantial interest are the investigations for direct 

 determination of inhibition of photosynthesis (Knepp, 1969). 



The authors proposed a number of modifications of the Knepp test, 

 including the use of Sccntdumui acuminatum, 5. bjugatiiA, and the diatom 

 StzphanodAAcuA hantzah-ii (Bereza, 1972, 1973) instead of S. quacUvtcauduA 

 as test species, and a modification of the oxygen method for determina- 

 tion of primary production and destruction of phytoplankton in the pre- 

 sence of toxicants. These modifications differ from the traditional 

 method in that a toxic component of required concentration is added to 

 the bottles as a control. The experiment then determines primary pro- 

 duction and destruction by the generally accepted method (Winberg, 

 1960). Investigations have shown that this test is not universal and 

 may have an indicative value when dealing primarily with ions of heavy 

 metals. 



Under the action of heavy metals, the correlation of primary produc- 

 tion and destruction is vastly altered. Copper, for example, influences 

 both processes, while zinc increases destruction (Table 2). 



In investigations of pollution of water by stable pesticides capable 

 of inhibiting phytoplankton photosynthesis, the test in which the inten- 



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