Zooplankton community structure in the Gopło lake, zooplankton hitch-hikers infiltrated into beakers through plankton nets and their fates after ten days of the incubation in filtered lake water from the Kierskie lake without and with resident T. obliquus (Resident(–), Resident(+); respectively). Abbreviations: ROTIF – Rotifera, COPEP – Copepoda, CLADO – Cladocera.