Studies were carried out in Lake Mutek (Mazurian Lakeland) on the effect of artificial aeration and destratification upon quantitative changes in the phytoplankton. These studies were carried out from 1977 until 1983. Two different methods of aeration were used. Low intensity mixing resulted initially i n a two-fold, and later on in a four-fold increase of the phytoplankton biomass. Increase of phytoplankton biomass during lake aeration was due t o the development of Ceratiutn hirudinella. Use of a highly effective air-compressor caused a n inhibition of algal development, so that biomass dropped to levels noted in the control year. It was found that the effect of aeration depended on the ratio between lake area and effectiveness of the aerator. Only intensive mixing of the water masses resulted in an inhibition of the development of algae. The effect of artificial destratification was also reflected in changes of the species structure, seasonal succession of the algae, and physiological state of the phytoplankton. Artificial circulation stimulated development of algae characterized by relatively high specific weight, i.e. most of all of P~~rrophj~ta, Bacillariophj~~eae and some species of Chlorophj-to. Various aspects were discussed of the use of direct aeration as a technical method of lake restoration.
Hydrobiologia 122, 89-96 (1985). O Dr W . Junk Publishers. Dordrecht.