Ecological Systems and Devices Annotation << Back Effect of potassium dichromate on the development and the population structure of the unicellular algae monoraphidium arcuatum (korsh.) Hind. (Chlorococcales) Spirkina N.E. DmitrievaA.G. Filenko O.F. Ipatova V.I. Experiments were conducted to identify the effect of potassium dichromate on the culture of microalgae Monoraphidium arcuatum (Chlorococcales) using standard ecotoxicological techniques and the author’s method of microcultures. The data on the toxicity of this substance to M. arcuatum is consistent with the results of foreign researchers for phylogenetically related species of algae. Toxic effects of potassium dichromate were manifested in slowing down the processes of cell division in a concentration of 1 mg/L–1 and its total inhibition at a concentration of 10 mg/L–1. In populations exposed to both of toxic concentrations structural changes were taking place. Established for 96 hours EC50 was in the range of sensitivity, recommended for Sc. quadricauda, which is widespread in a practice of bioassay. This suggests a rather high sensitivity of M. arcuatum laboratory cultures and opportunities to use it as a test-object in the toxicological assays to evaluate water quality. Key words: green microalgae; Monoraphidium arcuatum; potassium dichromate; the structure of the population. Contacts: E-mail: viipatova@hotmail.com Pp. 36-42.