Abstract
The article is focused on zooplankton of four cut backwaters in the middle course of the Elbe River (Semín and Votoka in the north of Přelouč, Kluk near Poděbrady and Vrť at Lysá nad Labem). All cut backwaters were created by the river regulation.
The zooplankton samples were taken in years 2004 to 2007 quarterly (nine in total) with plankton net (mesh size 40 μm). The species composition was observed.
The data were analysed using multidimensional statistical methods. Eighty species of zooplankton in total were found in the lakes.
Rotifers were dominating in lakes Semín, Votoka and Vrť due the strong predation pressure of fish. Small species of Rotifera (Keratella, Polyarthra, Synchaeta and Asplanchna) were present in all samples.
Species composition of Copepoda was pure (Cyclops vicinus, C. strenuus, Thermocyclops crassus, T. oithonoides). Cladocera were represented by 19 species (the most abundant - Bosmina longirostris, Daphnia cucullata, D. ambigua).
Less common (Bosmina coregoni, Pleuroxus denticulatus, P. uncinatus) and rare species (Anchistropus emarginatus, Pseudochydorus globosus) were also found. The most similar zooplankton species composition during the year was observed in Kluk Lake.
Seasonal development of species representation in lakes is individual. Based on the relative presence of individual groups of zooplankton (Rotifera, Copepoda, Cladocera), the lakes were classified into the following two groups: (i) lakes with prevailing rotifers in zooplankton (Vrť, Votoka, Semín) and (ii) Kluk Lake with larger species of zooplankton.