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          Institute: MPI für Evolutionsbiologie     Collection: Ecophysiology     Display Documents

ID: 3932.0, MPI für Evolutionsbiologie / Ecophysiology
Rapid Daphnia-mediated changes in microbial community structure: an experimental study
Authors:Degans, Hanne; Zöllner, Eckart; Van der Gucht, Kathleen; De Meester, Luc; Jürgens, Klaus
Date of Publication (YYYY-MM-DD):2002-10
Title of Journal:FEMS Microbiology Ecology
Journal Abbrev.:FEMS Microbiol. Ecol.
Issue / Number:1
Start Page:137
End Page:149
Review Status:Peer-review
Audience:Not Specified
Abstract / Description: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.
Free Keywords:Daphnia grazing; bacterioplankton; morphotype; DGGE
External Publication Status:published
Document Type:Article
Affiliations:MPI für Evolutionsbiologie/Abt. Ökophysiologie
External Affiliations:Katholieke Univ Leuven, Aquat Ecol Lab, De Beriotstr 32, B-3000
Louvain, Belgium
RU Gent, Lab Aquat Ecol & Protistol, B-9000 Ghent, Belgium
Identifiers:ISI:000178607900014 [ID-No:1]
ISSN:0168-6496 [ID-No:2]
LOCALID:2099/S 37811 [Listen-Nummer/S-Nummer]
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