SS2.04 Microbial Stoichiometry and Impacts on Biogeochemistry: From Genes to the Biosphere
Date: Friday, June 14, 2002
Time: 9:15:00 AM
Location: Carson C
 
Baines, S, B,  Marine Sciences Research Center, Stony Brook University, Stony Brook, NY, USA, sbaines@ms.cc.sunysb.edu
TwiningBS,  Marine Sciences Research Center, Stony Brook University, Stony Brook, USA, btwining@ic.sunysb.edu
Fisher, N, S,  Marine Sciences Research Center, Stony Brook University, Stony Brook, NY, USA, nfisher@notes.cc.sunysb.edu
Maser, J, M, Advanced Photon Source, Argonne National Laboratory, Argonne, IL, USA, maser@aps.anl.gov
Jacobsen, C, , Department of Physics, Stony Brook University, Stony Brook, NY, USA, jacobsen@xray1.physics.sunysb.edu
 
TRACE ELEMENT CONCENTRATIONS AND STOICHIOMETRIES IN PLANKTONIC PROTISTS MEASURED WITH AN X-RAY FLUORESCENCE MICROPROBE.
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Despite the importance of understanding trace element concentrations in planktonic protists, reliable measurements of metal concentrations in marine plankton are rare, in part because present analytical approaches cannot differentiate between abiotic or biotic particles, or between functionally different organisms of the same size. In this study, we present measurements of trace element concentrations in individual protistan cells using a fluorescence x-ray microprobe associated with the synchrotron at Argonne National Laboratory. The microprobe yields credible estimates of Fe, Zn and Cu contents of algal and protozoan cells >2 μm. Observed differences in Fe:C, Zn:C and Cu:C ratios of diatoms, ciliates, and heterotrophic nanoflagellates from the coastal Atlantic indicate that heterotrophic protists are efficient at recycling trace elements from prey, and that flagellates are more efficient than ciliates in this regard. More data from Lake Erie and from the SOFeX iron addition experiment in the Southern Ocean will be used to test the generality of this conclusion. The x-ray microprobe is a high-sensitivity high-spatial resolution technique for measuring trace elements that will enable study of biogeochemical and ecological interactions at the microbial scale.