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Testing the competition-colonization trade-off with benthic
ciliates
Romana Limberger, Steve Wickham
University of Salzburg, Austria
Ecological theory postulates a trade-off between competition and
colonization ability. This hypothesis was tested with artificial benthic
communities in two microcosm experiments. Tiles covered by a biofilm
of a benthic diatom, bacteria and heterotrophic flagellates were
used as artificial substrates. Six benthic ciliate species served as test
organisms. For each species, colonization ability was measured by
connecting two microcosms and detecting the time necessary to reach
the initially uncolonized microcosm. For measurement of competitive
ability, species were added pair-wise to unconnected microcosms.
The species with the higher biomass at the end of the experiment was
regarded as the better competitor.
Species strongly differed in their colonization ability. Colonization
time ranged from 1.7 to 8.7 days. A clear winner and a clear loser
were found in the competition experiment, but also some species with
similar competitive abilities. The relationship between competitive
and colonization ability was positive rather than negative, contrary to
the competition-colonization trade-off hypothesis.
romana.limberger@sbg.ac.at
steve.wickham@sbg.ac.at
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