Response of primary production and calcification to changes of pCO2 during experimental blooms of the coccolithophorid Emiliania huxleyi -: art. no. GB2023

[1] Primary production and calcification in response to different partial pressures of CO2 (PCO2) ("glacial,'' "present,'' and "year 2100'' atmospheric CO2 concentrations) were investigated during a mesocosm bloom dominated by the coccolithophorid Emiliania huxleyi. The day-to-day dynamics of net community production (NCP) and net community calcification (NCC) were assessed during the bloom development and decline by monitoring dissolved inorganic carbon (DIC) and total alkalinity ( TA), together with oxygen production and 14 C incorporation. When comparing year 2100 with glacial PCO2 conditions we observed: ( 1) no conspicuous change of net community productivity (NCPy); ( 2) a delay in the onset of calcification by 24 to 48 hours, reducing the duration of the calcifying phase in the course of the bloom; ( 3) a 40% decrease of NCC; and ( 4) enhanced loss of organic carbon from the water column. These results suggest a shift in the ratio of organic carbon to calcium carbonate production and vertical flux with rising atmospheric PCO2.