Zooplankton succession and thermal stratification in the polymictic shallow Muggelsee (Berlin, Germany): a case for the intermediate disturbance hypothesis?

From the end of May to November 1995 the succession of rotifers and cladoce rans was investigated in Muggelsee with samples taken twice a week. Keratel la cochlearis was the only rotifer which was found on every sampling day an d this species also showed the highest abundances. During summer, when freq uencies of strong wind events were low and water was strongly stratified, t hree small cladocerans were dominant (Daphnia cucullata, Chydorus sphaericu s, Eubosmina coregoni). Food supply was the main limiting factor for Kerate lla spp. and Synchaeta spp. In autumn, however, when the intervals between strong winds were shorter, rotifers with shorter periods for population dev elopment prospered. Zooplankton diversity first increased and subsequently decreased after disturbances. The results do not support the intermediate d isturbance hypothesis in its present formulation.