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GLIN==> May 13 Seminar - Ann Arbor



NOAA GREAT LAKES SEMINAR SERIES
http://www.glerl.noaa.gov/news/seminars/

Title: "The Importance of the Microbial Food Web in C- and P- Transport 
through the Base of Great Lakes Food Webs"

Speaker: Dr. Robert Heath,
Kent State University

Date: Tuesday, May 13, 2003

Time: 10:30 a.m.

Where:
GLERL Main Conference Room
2205 Commonwealth Blvd.
Ann Arbor, MI 48105
For directions:
http://www.glerl.noaa.gov/facil/triptik.html

Abstract:
We examined factors that controlled bacterial cell P composition and 
rate of phosphate uptake in laboratory and field studies. Pseudomonas 
fluorescens (ATCC 13525) as a model of bacterium was cultured in M9 
minimal medium adjusted to have low phosphate concentrations similar to 
those found in the field (50  200 nM) and using glutamate as the sole 
C-source (100  400 ýM). Natural assemblages of bacterioplankton were 
examined along a trophic gradient in Lake Erie, ranging from the heavily 
eutrophic SanduskyBay to the mesotrophic central basin.Bacterially 
available phosphate concentrations ranged from 1 to 148 nM; labile 
dissolved organic carbon (LDOC) ranged from 15 to 170 ýM. As LDOC 
increased, bacterioplankton growth rate and biovolume increased, but 
cell P content and velocity of phosphate uptake decreased. Both in 
culture studies and in natural assemblages of bacterioplankton we found 
that LDOC was the major factor controlling phosphate uptake by 
bacterioplankton.We also measured rates of bacterivory in nearshore and 
offshore stations in the field using fluorescently labeled algae and 
bacteria. From these findings we conclude that the microbial food web is 
an important link in P-transport to zooplankton but it is seldom if ever 
an important link in C- transport.

For more information, contact: 

Rochelle Sturtevant
734-741-2287
Rochelle.Sturtevant@.noaa.gov



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Posted by:

David F. Reid, Ph.D.
U.S. Department of Commerce
National Oceanic and Atmospheric Administration
Great Lakes Environmental Research Laboratory
2205 Commonwealth Blvd.
Ann Arbor, MI  48105-2945
Voice:	734-741-2019
FAX:	743-741-2055
GLERL home page:
   http://www.glerl.noaa.gov



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