HR: 0800h
AN: OS51C-1307    [Abstracts]
TI: Calcification and Growth of the Marine Coccolithophorid Emiliania huxleyi in Response to Elevated Partial Pressure of Carbon Dioxide and Low Phosphate Conditions
AU: * Faber, D N
EM: dfaber@csusm.edu
AF: California State University San Marcos, Department of Biological Sciences, San Marcos, CA 92096-0001 United States
AU: Fabry, V J
EM: fabry@csusm.edu
AF: California State University San Marcos, Department of Biological Sciences, San Marcos, CA 92096-0001 United States
AU: Dickson, A G
EM: adickson@ucsd.edu
AF: University of California San Diego Scripps Inst. of Oceanography, 9500 Gilman Drive, La Jolla, CA 92093 United States
AB: Atmospheric carbon dioxide (CO2) is expected to reach about 780 ppm by the year 2100, under the IS92a business-as-usual scenario. This expected increase will give rise to more than a threefold increase in surface ocean CO2 concentration, cause a drop in surface seawater pH of 0.4 units, and decrease the carbonate ion concentration by 55%, relative to pre-industrial values. Previous work demonstrated that the coccolithophorid Emiliania huxleyi shows a marked decrease in calcification rates in response to elevated CO2 under nutrient-replete and nitrogen-limited conditions. Here we investigate the response of E. huxleyi to increased pCO2 under phosphate limitation. Results from laboratory and mesocosm experiments indicate that E. huxleyi can outcompete other phytoplankton in communities that are under phosphate control. Moreover, E. huxleyi has higher calcification rates under phosphate limitation, and model studies suggest that low phosphate levels are necessary for E. huxleyi to form dense blooms in the NE Atlantic. We grew E. huxleyi cells in 8-L closed systems under low phosphate conditions at present day and elevated pCO2 concentrations. Cell growth, particulate inorganic carbon, particulate organic carbon, total alkalinity and total dissolved inorganic carbon were measured over time. Results will be discussed in relation to predicted changes in the oceanic CO2/carbonate system.
DE: 4805 Biogeochemical cycles (1615)
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting