Fishpond trophic status assessment based on nutrients and bioindication I. Phytoplankton

Two-year-study of selected environmental variables, phytoplankton abundance, structure and species composition at 12 fishponds was used for the evaluation of their trophic state. Favourable conditions of Bouzov fishponds are probably influenced by their disposition in the landscape. On the contrary, fishponds near Hradec Kralove are strongly endangered by rapid eutrophication. The negative development of fishponds can be mitigated only by rigorous management excluding intensive fish or duck production, recreation, and agriculture in the surrounding fields. Prevention of external and internal loading and forestation of wide surroundings can be recommended.