Epizoic rotifers on Dreissena polymorpha in relation to biotic factors

Abstract

Mollusks represent one of the most important components of freshwater zoobenthos and their shells provide a substrate for many organisms creating epibiotic communities of predominantly facultative nature. We determined rotifer species that colonize shells of Dreissena polymorpha (Pallas, 1771) without and with presence of large Cladocera and fish, alone and together. The experiment was conducted in 12 mesocosms filled with water from the littoral zone of a eutrophic lake. The experiment involved four treatments (three replicates each): (1) control of D. polymorpha in lake water; (2) D. polymorpha in lake water with the addition of large Cladocera; (3) D. polymorpha in lake water with the addition of fish; and (4) D. polymorpha in lake water with the addition of large Cladocera plus fish. The study revealed that epizoic rotifer fauna found on D. polymorpha is relatively abundant and rich in species, different from plankton communities in the same mesocosms, and specific, that is, include species that prefer this habitat. It may also suggest that communities of epizoic rotifers are impacted by the presences of benthic predators, as well as by small fish and large crustaceans inhabiting littoral waters.