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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 6985

John R. Beaver and Thomas L. Crisman; The trophic response of ciliated protozoans in freshwater lakes. Limnol.Oceanogr. 27(2):246-253, 1982

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The abundance, biomass, composition, and size distribution of planktonic ciliated protozoans were analyzed monthly during 1979 along a trophic gradient represented by 20 Florida lakes. Both the abundance and biomass of ciliates were positively related to trophic state. Eutrophic assemblages were codominated by members of the Scuticociliatida, Oligotrichida, and Haptorida; oligotrophic lakes were dominated principally by the Oligotrichida. In addition to a compositional shift, large-bodied ciliates (40-50 µm) were progressively replaced by small-bodied ciliates (20-30 µm) as trophic state increased. The response is attributed to changes in food availability. Small-bodied (<30 µm) bactivorous taxa are reduced in oligotrophic lakes where bacterial concentrations are limiting and replaced by those larger-bodied taxa (>30 µm) able to ingest nannoplanktonic algae in addition to bacteria.