RESUMO

The influence of the increase in the content of phosphorus and nitrogen in the water of the Dnieper reservoirs on the quantitative indices of development of phytoplankton with a predominance of Cyanophyta and Bacillariophyta, and also on the processes of its production and decomposition, was studied in summertime. It has been found that the increase in the content of inorganic phosphorus dissolved in water up to more than 0.2 mg P/L resulted for the most part in phytoplankton growth inhibition and in the decrease in the intensity of its photosynthesis. Its influence increased with increasing pH value. The increase in the content of nitrate stimulated the development of phytoplankton. The response of algae to the introduction of ammonium depended on its concentration.