Environmental changes are important factors related to shifts in species compositions and abundances of aquatic communities. This study presents the responses of cladoceran communities to realistic scenarios of an increase in temperature and phosphorus concentration. This study was conducted under laboratory conditions, and the outcomes of this study explain the causes of seasonal shifts in both abundance and species composition and allow us to predict their responses to climatic changes in aquatic ecosystems. The results showed that temperature increase was the more important trigger of shifts than phosphorus increase. Moreover, the simultaneous influence of increases in temperature and phosphorus concentration had a significantly higher impact than single factors. Under all the scenarios, the increased contributions of species that were dominant before the changes and the extinction of rare species were observed. Ultimately, cladoceran communities displayed functional overcompensation and loss of species in comparison to prechanged communities.