Ref ID : 7230
Helga Muller and Thomas Weisse; Laboratory and field observations on the scuticociliate Histiobalantium from the pelagic zone of Lake Constance, FRG. J.Plankton Research 16(4):391-401, 1994
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Histiobalantium sp., was found regularly in the pelagic zone of Lake Constance, FRG, over five annual cycles. Maxima of up to 6400 cells l-1 were recorded in late summer, with similar numbers in the 0-8 and 8-20 m depth intervals. On an annual average, the population accounted for 10-17% of the total biomass of planktonic ciliates. In the laboratory, Histiobalantium grew well on a diet of the cryptophyte Rhodomonas sp. Maximum growth rates obtained in batch cultures were 0.21 and 0.33 day-1 at 9 and 18 degrees C, respectively. In situ experiments using diffusion chambers yielded positive growth rates in autumn and winter. The highest values recorded at the ambient temperatures 5, 14 and 17 degrees C were 0.17, 0.32 and 0.40 day-1, respectively. Comparing these results with the different seasonal distributions and higher measured growth rates of other ciliates from Lake Constance, we conclude that Histiobalantium is a superior competitor at relatively low algal food concentrations.