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Abstract

The population dynamics of the ciliated Protozoa in Marion Lake sediment are examined. Densities of ciliates range from 10-100/cm², with the yearly mean being 51/cm². Ciliate density is not correlated with rainfall, but is correlated with temperature. However, when the data is detrended, no correlations appear. The number of individuals and the number of species present in a sample are correlated, A negative correlation is found between ciliate density and the populations intrinsic rate of increase at both 1 and 4 meters depth. It is concluded that the ciliate population cannot be controlled by food limitation as the ciliates cannot influence the size of the bacterial population, and the predation rate is not large enough to have a regulatory influence on the ciliate population. The ciliates make an energetic contribution to higher trophic levels, but it probably unimportant when compared to that of the bacteria and microalgae. For deposit feeders, the ciliates are energetically unimportant. However, benthic meiofaunal predators such, as cyclopoid copepods and their nauplii may- be supplied with a considerable amount of their daily energy needs by the ciliates.