Delille B, Harlay J, Zondervan I, Jacquet S, Chou L, Wollast R, Bellerby RGJ, Frankignoulle M, Borges AV, Riebesell U, Gattuso JP
calcification, co2, acidification, coccolithophores, Emiliania huxleyi, mesocosm, Raunefjorden, Espegrend, Bergen, Norway, 11 m3
Primary production and calcification in response to different partial pressures of CO2(PCO2) (‘‘glacial,’’ ‘‘present,’’ and ‘‘year 2100’’ atmospheric CO2 concentrations) wereinvestigated during a mesocosm bloom dominated by the coccolithophorid Emilianiahuxleyi. The day-to-day dynamics of net community production (NCP) and netcommunity calcification (NCC) were assessed during the bloom development and declineby monitoring dissolved inorganic carbon (DIC) and total alkalinity (TA), togetherwith oxygen production and 14C incorporation. When comparing year 2100 with glacialPCO2 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 theduration 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 ashift in the ratio of organic carbon to calcium carbonate production and vertical fluxwith rising atmospheric PCO2.