Title: Rapid Daphnia-mediated changes in microbial community structure: an experimental study
Authors: Degans, Hannelore ×
Zollner, E
Van der Gucht, K
De Meester, Luc
Jurgens, K #
Issue Date: Oct-2002
Publisher: Published by Elsevier Science Publishers on behalf of the Federation of European Microbiological Societies
Series Title: FEMS Microbiology Ecology vol:42 issue:1 pages:137-149
Abstract: Shifts in morphological and taxonomical composition of bacterioplankton communities in response to protist and metazoan grazing were studied in bottle experiments, exposing bacterioplankton from a eutrophic clear-water pond, dominated by a large population of Daphnia magna, to a Daphnia gradient, ranging from 0 to 60 individuals per liter. Prior to the first experiment, the bacterioplankton community was shaped by protist grazing, while for the second experiment, bacterioplankton was pre-adapted to Daphnia grazing. In both experiments, rapid shifts in biomass and structure of the bacterioplankton community upon exposure to Daphnia grazing were observed. High Daphnia densities suppressed protozoa, resulting in a dominance of free-living bacteria. Under low Daphnia densities, heterotrophic nanollagellates (HNF) developed as the dominant grazers and complex morphotypes (filaments, aggregates) were abundant in the bacterial community. Denaturing gradient gel electrophoresis analysis showed that taxonomical changes accompanied the morphological differences between bacterial communities shaped by HNF or Daphnia grazing. However, comparing ciliate- and Daphnia-dominated bacterial communities, we observed a discrepancy between morphological and taxonomical shifts, indicating that other traits than mere morphological ones determine vulnerability of bacterioplankton to specific grazers. Our results illustrate the rapid, pronounced and reversible impact of grazing on the morphology and taxon composition of bacterioplankton. Our results also stress that Daphnia may, already at moderate densities, have a pronounced impact on the lake bacterioplankton, both through direct grazing on the bacteria and through grazing on protozoan bacterivores. (C) 2002 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.
ISSN: 0168-6496
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Ecology, Evolution and Biodiversity Conservation Section
× corresponding author
# (joint) last author

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