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AME 34:181-192 (2004)
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Abstract
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Effect of suspended clay on the feeding and growth of bacterivorous flagellates and ciliates
Jens Boenigk1,2,*, Gianfranco Novarino2
1Institute of Limnology, Austrian Academy of Sciences, Mondseestr. 9, 5310 Mondsee, Austria
2The Natural History Museum, Department of Zoology, Protista & Mathematics Division, Cromwell Road, London SW7 5BD, UK
*Email: jens.boenigk@oeaw.ac.at
ABSTRACT: The effect of suspended fine sediment on protist growth and behaviour was investigated using kaolinite-dominated clay with a mean grain size of 0.9 µm. Suspended sediment particles about the same size as potential food items of picovorous
organisms, i.e. bacteria, were expected to interfere with feeding. Growth rates of Halteria sp. and Tetrahymena pyriformis were 0.056 and 0.15 h-1 irrespective of the clay concentration, Cyclidium sp. showed slightly higher
but significant growth rates in the presence of clay, as did most flagellates. The largest difference in growth was found for Spumella sp., which showed rates of 0.19 and 0.14 h-1 with and without clay, respectively. An exception was
the gliding flagellate Entosiphon sulcatum, which was covered by clay particles and therefore hardly came in contact with food particles. Flagellates discriminated strongly against sediment particles prior to food uptake. With decreasing particle
concentration this selection mechanism became less important compared to differential digestion especially in Spumella sp. and an unidentified groundwater flagellate. Both Bodo saltans and Monosiga ovata showed differential digestion
as well, but their importance in overall selectivity was low even at a low particle concentration. In contrast to flagellates, the ciliates collected many particles, including clay particles and bacteria, and incorporated them into 1 food vacuole.
Discrimination against clay was of minor importance in ciliates, but a high feeding capacity seems to compensate for this low selectivity. In contrast to many zooplankton species, it can be concluded that protists are generally well adapted to
environmental situations of high sediment load.
KEY WORDS: Microbial food web · Suspended matter · Feeding strategy · Bacterivory · HNF · Plankton · Runoff · Resuspension
Full text in pdf format
Published in AME Vol.
34, No. 2
(2004) on February 4
Print ISSN: 0948-3055; Online ISSN: 1616-1564.
Copyright © Inter-Research, Oldendorf/Luhe, 2004
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