| Abstract: | In high-rate algal ponds, the grazing activity of rotifers such as Brachionus rubens or B. calyciflorus often leads to a replacement of Scenedesmus species by Micractinium pusillum. In contrast to many other green microalgae including Scenedesmus, Micractinium pusillum with fully developed spines (setae) cannot be eaten by Brachionus. Ecological conditions for population shifts between Scenedesmus and Micractinium are, therefore, interpreted as a response of the rotifers rather than being due to physiological properties of the algae. Another effect of rotifer grazing on the microbial flora of high-rate ponds is the development of large stable flocs consisting of bacteria and microalgae. |
