Habitat conditions may shape the abundance and community structure of planktonic fauna. In this study, we investigated whether reservoirs with different locations and drainage basins also differed in the structure and abundance of zooplankton. The studies were conducted in 2010-2011 between June and October in the Vistula Lagoon and Lake Lebsko. The zooplankton was dominated mainly by small eurytopic organisms belonging to Rotifera. Plankton crustaceans showed a limited diversity of species. Copepods were predominant, while Cladocera were observed sporadically in more freshwater habitats. In the first experimental season (2010), the Vistula Lagoon and Lake Lebsko showed a comparable taxonomic structure and an abundance of investigated zooplankton; a substantially higher density was recorded in Lake Lebsko in 2011, although the taxonomic diversity was higher in the Vistula Lagoon. Zooplankton biomass in a given season differed between these 2 water bodies, but not statistically significantly. The differences in location in the investigated water bodies impacted zooplankton assemblage structure and abundance. The drainage basin type (urbanized areas, forested areas, waterlogged areas) appeared to influence zooplankton species richness significantly.

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