Ref ID : 1660
Carolyn W. Burns and John J. Gilbert; Predation on ciliates by freshwater calanoid copepods: rates of predation and relative vulnerabilities of prey. Freshwater Biology 30:377-393, 1993
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1. The susceptibility of ciliates in a mesotrophic lake to predation by Epischura lacustris, Diaptomus minutus and D. pygmaeus was assessed during summer. Oligotrichs, particularly Strobilidium velox (ca. 43 um), were removed efficiently by adult copepods and contributed substantially to the diet of female D. minutus. The presence of approximately 1.6 adult Epishchura l-1, or sixteen adult female Diaptomus l-1, could halt the growth of S. verox populations in summer. 2. Factors affecting the rate at which copepods prey on ciliates were examined in experiments with D. pygmaeus and cultured ciliates. Rate of predation on S. velox, the preferred species, become saturated at 5 S. velox ml-1 (45 ngC ml-1) and did not change with a 10-fold increase in alternative algal food. 3. Behavioural differences among ciliates, and the presence of other ciliates, contributed to differences in ciliate susceptibility to predation and suggest reasons why rates of removal of ciliates are not related to ciliate size. 4. By feeding selectively, at high rates, calanoids may suppress populations of some ciliates and thereby influence microzooplankton community structure.