The Crustcea and Rotifera in the pond near «Piramida» shopping mall (Samara) in 2013

The composition and population sizez of the Crustacea and Rorifera species were studied in an urban pond after its melioration. 30 Rotifera species (52 species before melioration) and 20 Crustacea species (33 species before melioration) were found in 2013. Brachionidae, Synchaetidae и Asplanchnidae remain dominant in the Rotifera community. Cyclopoidae were dominant in the Crustacea community (Daphniidae dominated before melioration). The quantity of Bosminidae и Chydoridae considerably increased. On the whole the quantity of animal plankton decreased by 15% in 2013. In 2010 rises of the quantity were observed twice, in June and in August; in 2013 there was only one rise of the quantity of the plankton in July. The number of female individuals with eggs increased. The pond refers to the β-mesosaprobic zone, the level of contamination in terms of saprobity indicators decreased. The Shannon index of species diversity was calculated. Removal of macrophytes caused decrease of littoral species and growth of plankton invertebrates. The hydrochemical analysis revealed the excess of the maximum permissible concentration of BOC₅, АSАS, Cu, Fe and Zn.