HR: 11:45h
AN: OS52A-06    [Abstracts]
TI: Ocean Biogeochemistry and Phytoplankton Ecology in a Global Simulation
AU: * Moore, J K
EM: jkmoore@uci.edu
AF: University of California, Irvine, Department of Earth System Science, Irvine, CA 92697 United States
AU: Doney, S C
EM: sdoney@whoi.edu
AF: Woods Hole Oceanographic Institution, Dept. Marine Chemistry and Geochemistry MS #25, Woods Hole, MA 02543 United States
AU: Lindsay, K
EM: klindsay@ucar.edu
AF: National Center for Atmospheric Research, Oceanography Section P.O. Box 3000, Boulder, CO 80307 United States
AB: A coupled Biogeochemistry/Ecosystem/Circulation (BEC) model is used to examine ocean biogeochemistry and phytoplankton ecology at the global scale. Phytoplankton groups represented in the model include diatoms, diazotrophs, coccolithophores and picoplankton. The groups experience differential grazing pressure and compete for light and the potentially growth-limiting nutrients iron, nitrate, ammonium, phosphate, and silicate. The model includes several key aspects of the global nitrogen cycle including nitrogen fixation (by the diazotrophs), water column denitrification under low oxygen conditions, and atmospheric nitrogen deposition to the oceans. We examine how these nitrogen fluxes influence ecosystem structure and also how light and nutrient availability restrict phytoplankton growth rates over seasonal timescales. Atmospheric deposition of mineral dust also inputs dissolved iron to the ocean model. These iron additions modify phytoplankton community composition, and rates of production and export in the iron-limited High Nitrate, Low Chlorophyll regions, and indirectly modify ecosystem dynamics by altering rates of nitrogen fixation in nitrogen-depleted, tropical and subtropical regions. We will examine the links between dust/iron deposition and nitrogen cycling in the oceans.
DE: 1615 Biogeochemical processes (4805)
DE: 4805 Biogeochemical cycles (1615)
DE: 4815 Ecosystems, structure and dynamics
DE: 4842 Modeling
SC: Ocean Sciences [OS]
MN: 2005 Joint Assembly