Paramecium - Deutsche Gesellschaft für Protozoologie / German ...

Size dependent interaction of flagellates with microcurrents
around obstacles
Annette Schlüssel, Hartmut Arndt
Department of General Ecology and Limnology, University of Cologne
Boundary layers serve as an environment for heterotrophic nanoflagellates
in running waters. Although the influence of surface topography
on hydrodynamics for macrofauna was studied several times,
investigations in the layer between 2 and 5 µm are rare. Former studies
showed that even low flow velocities can cause the detachment
of nanoflagellates. The present study analysed, if the detachment of
morphologically similar cercomonads in currents behind micro-topographies
(Ancylus fluviatilis shells) varies with their cell sizes. Three
different cercomonads with sizes from 5 to 27 µm and one bodonid of
5 µm size were analysed. At a flow velocity of 0.3 m s -1 small flagellates
were not affected, but large cercomonads showed high detachment
rates. These data indicated a size dependent effect of microcurrents
on nanofauna. In addition, the influence of a complex surface
topography like an artificially modelled biofilm was studied for the
current-sensible flagellate Cercomonas crassicauda. The results conveyed
that only flagellates in sheltered regions stayed attached. Individuals
at exposed areas were washed away by the current and were
not capable of actively moving into the sheltered areas.
annette.schluessel@uni-koeln.de
hartmut.arndt@uni-koeln.de
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