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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 7100

Matsuyama Michiro and Sang-Wook Moon; Feeding of a Hypotrichous Ciliate swimming in the H2S layer of Lake Kaiike on Chromatium sp. Jap.J.Limnol. 58:61-67, 1997

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A freely swimming hypotrichous ciliate was found in all samples from different depths of the H2S layer in Lake Kaiike on 24 May 1996 (<10 cells ml-1). Growth of these ciliates was tested by adding living cells of Chromatium sp., a phototrophic bacterium blooming at an upper boundary of the H2S layer (bacterial plate). The bacterium was found to be an effective food for the ciliates in the lake. If the ciliate growth rate, estimated as a maximum 0.6 day-1, was assumed to be determined solely by bacterial cell density, a single ciliate cell would soon grow to 2500 cells (a number sufficient to consume the entire bacterial population). However, results suggest that growth of the ciliates in the lake was greatly controlled by other environmental factors such as predation by larger zooplankton or by the occurrence of a high concentration of H2S at and around the bacterial plate. The ciliates found in the H2S layer appeared to be those expelled from their original habitat.