SS2.04 Microbial Stoichiometry and Impacts on Biogeochemistry: From Genes to the Biosphere
Date: Friday, June 14, 2002
Time: 10:45:00 AM
Location: Carson C
 
Van MooyB, University of Washington, Seattle, USA, bvm@ocean.washington.edu
Grocock, J, L, University of Washington, Seattle, USA, jgrocock@u.washington.edu
Devol, A, H, University of Washington, Seattle, USA, devol@u.washington.edu
Keil, R, G, University of Washington, Seattle, USA, rickkeil@u.washington.edu
 
BACTERIOPLANKTON COMMUNITY STUCTURE AFFECTS RESPONSE TO BIOAVAILABLE DOC IN THE EASTERN SUBARCTIC PACIFIC
image
Bacterioplankton were filtered from the coastal and offshore waters of the eastern subarctic North Pacific for community analysis by t-RFLP. Samples were obtained at stations and depths that spanned two orders of magnitude in thymidine uptake and chl-a concentration. Separate thymidine incorporation experiments were amended with 50 uM of biochemicals with C/N ratios of 3.7 (amino acids or protein) or C/N ratios of 8 (N-acetylglucosamine or mildly-hydrolyzed chitin). The amendments had varying effects on thymidine incorporation, but neither, chl-a, nutrients, depth nor distance from shore correlated with the magnitude or sign of the community response to these amendments. The bacterial communities could be designated as belonging to one of two distinct groups using t-RFLP of 16S rRNA genes. When the thymidine incorporation rates of amended experiments were examined in this context, clear differences in the response of the community groups to the different amendments were revealed. Thus it appeared that bacterial community composition, not chemical conditions as determined by our measurements, most strongly affected the capacity of bacteria to utilize dissolved biochemicals.