SS2.05 Phylogenetic and Physiologic Successions in Aquatic Bacterial Communities
Date: Monday, June 10, 2002
Time: 11:45:00 AM
Location: Carson C
 
BouvierTC, Université du Québec à Montréal, Montréal, Canada, Tbouvier@hpl.umces.edu
del Giorgio, P, A, Université du Québec à Montréal, Montréal, , del_giorgio.paul@uqam.ca
 
SHORT-TERM VARIABILITY IN BACTERIOPLANKTON PHYLOGENY AND METABOLISM IN A TEMPERATE SALT-MARSH OVER TIDAL CYCLES
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Tidal marshes are sites of dramatic short-term fluctuations of environmental factors, and it is now clear that bacterioplankton community metabolism responds to these environmental fluctuations. It is less clear, however, whether the response of bacterioplankton also involves substantial changes in the phylogenetic composition of the assemblage. We have followed the short-term changes in bacterioplankton phylogenetic composition within single tidal cycles in a salt-marsh tidal creek that flows into the Choptank River, a tributary of the Chesapeake estuary. We carried out intensive in situ time courses in spring, summer and fall. We have further attempted to link the changes in phylogenetic diversity to the variability of the in situ physiological state of the bacterioplankton cells and bulk metabolic activity during the tidal cycle. Phylogenetic composition was analyzed using Fluorescence In Situ Hybridization combined with several measures of single cell activity. Our results indicate that broad phylogenetic groups fluctuated differently during the tidal cycle, resulting in shifts in phylogenetic dominance. These transitions were accompanied with dramatic changes in the physiological state of the bacterioplankton, which were reflected in the metabolism of the community.