Abstract
Statistically significant differences between phytoplankton of the pelagic area and littoral zone, overgrown with macrophytes, were observed in seven reservoirs and three natural lakes. Both total biomass and species diversity of the phytoplankton were higher in the macrophyte settlements than in the pelagic zone. Regarding biomass, the divisions of Pyrrhophyta and Cryptophyta were the main contributors to the similarity of the pelagic areas while the pennate Bacillariophyta were the main contributors to the similarity of macrophyte zones. The phytoplankton structure in the littoral zone differed also within the same water body but in sites with different macrophyte dominant species, as the differences concerned mainly the ratio between pennate diatoms and conjugatophyceans.