The influence of temperature and pH of water on the development of chosen species of algae and cyanophytes (Cyanobacteria, Cyanoprocaryotes) causing water blooms in two dam reservoirs, was studied. Their mass development was observed in various seasons of the year. Each species preferred different environmental conditions. The dominating species of phyto-plankton varied in both reservoirs, only dinoflagellate Ceratium hirundinella being the exception.
E. Wilk-Wozniak, Karol Starmach Institute of Freshwater Biology, Polish Academy of Sciences Slawkowska 17, 31-016 Krakow, Poland, e-mail: wilk@zbw.pan.krakow.pl