The examined Lake Lubaskie Duze covering the area of 41.5 ha is a dimictic lake a mean depth of 12 m (max. depth 16 m). The systematic observations of phyto- and zooplankton changes together with the selected physico-chemical parameters of water which were carried out for this lake during 1991-1996 showed its mesotrophic character declining towards eutrophy . In 1996, the research was expanded to the analyses of the plankton dynamics in the zones of rushes and submerged vegetation. The purpose of this research was to examine qualitative and quantitative changes of plankton inhabiting various habitats. The samples were collected along the transect starting from rushes to the area of open water (pelagic zone). The sampling was performe at four stations: station 1 - zone of rushes, community of reed and cattail; station 2 - zone of open water area between stations 1 and 3; station 3 - zone of submerged vegetation, community of hornwort; station 4 - open water (pelagic zone). Taking into consideration the spatial distribution of plankton, the differences in the taxonomic groups inhabiting the zones along the transect were noted. In the zone of submerged vegetation, the higher species diversity and greater numbers of specimens were observed than in the zone of rushes.