SS2.06 Microbial Diversity in Time and Space
Date: Tuesday, June 11, 2002
Time: 2:45:00 PM
Location: Lecture Theatre
 
WeisseT, Institute for Limnology of the Austrian Academy of Sciences, Mondsee, Austria, thomas.weisse@oeaw.ac.at
 
SPATIAL AND TEMPORAL INTRASPECIFIC VARIATION IN PLANKTONIC CILIATES
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Small heterotrophic flagellates, dinoflagellates and ciliates are the dominant bacterivores and, in oligo- to mesotrophic lakes, may be even the most important herbivores in planktonic food webs. Recent evidence suggests that variation in the ecophysiology of these protists is considerably larger than hitherto assumed. This presentation demonstrates surprisingly large intraspecific variation of several morphological (cell size) and ecophysiological (ingestion, growth and production rates) features of planktonic ciliates. New results, illustrating differences at the population level, will be presented from ongoing laboratory investigations with prostomatid and oligotrich ciliates. Ingestion rate of, e.g. Balanion planctonicum, may differ by a factor of three between populations obtained from the same lake (L. Constance, Germany) but at different times. Five clones of Coleps spetai isolated from Lake Mondsee, Austria, within six weeks differed twofold in their maximum growth rates, and growth of the various clones peaked at temperatures ranging from 12 to 21 C. Clonal differences in volume, growth and production rates were also found for several small Urotricha species and for Rimostrombidium lacustris.