Aquatic Sciences Meeting, Albuquerque 2001

SS14 Microbial Diversity (Disciplinary Connections)

Date: Monday, February 12, 2001, Time: 11:30:00 AM

Location: Brazos

Bouvier, T, C, University of Maryland Center for Environmental Science, Horn Point Laboratory, Cambridge, MD 21613, USA, tbouvier@hpl.umces.edu

del Giorgio, P, A, University of Maryland Center for Environmental Science, Horn Point Laboratory, Cambridge, MD 21613, USA, delgior@hpl.umces.edu

BACTERIOPLANKTON PHYLOGENETIC AND PHYSIOLOGIC SUCCESSION ALONG A SALINITY GRADIENT IN THE CHESAPEAKE BAY ESTUARY

The application of molecular approaches to assess in situ bacterioplankton composition has yielded broad across system patterns. However, little is known about the nature of the transitional succession from one type of system to another. We have explored the bacterioplankton phylogenetic succession along a salinity gradient in the Choptank River, a partially mixed estuarine tributary of the Chesapeake Bay. We have further attempted to link the changes in composition to shifts in the in situ physiological state of the bacterioplankton cells along this gradient. Phylogenetic composition was analyzed using Fluorescence In Situ Hybridization combined with several measures of single cell activity. Our results indicate that phylogenetic succession along a salinity gradient is not gradual, but rather occurs with sharp replacements of communities in and around the turbidity maximum. β-proteobacteria, Cytophaga-Flavobacterium group and α-proteobacteria are the most important groups detected in the freshwaters, the turbidity maxima, and in the marine waters, respectively. This rapid phylogenetic transition occurred with dramatic changes in the physiological state of the bacterioplankton, with clear evidence of cell stress and mortality.

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Aquatic Sciences Meeting, Albuquerque 2001

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