Simulating the effects of light intensity and carbonate system composition on particulate organic and inorganic carbon production in Emiliania huxleyi.
Coccolithophores play an important role in the marine carbon cycle. Variations in light intensity and external carbonate system composition alter intracellular carbon fluxes and therewith the production rates of particulate organic and inorganic carbon. Aiming to find a mechanistic explanation for the interrelation between dissolved inorganic carbon fluxes and particulate carbon production rates, we develop a numerical cell model for Emiliania huxleyi, one of the most abundant coccolithophore species. The model consists of four cellular compartments, for each of which the carbonate system is resolved dynamically. The compartments are connected to each other and to the external medium via substrate fluxes across the compartment-confining membranes. By means of the model we are able to explain several pattern observed in particulate organic and inorganic carbon production rates for different strains and under different acclimation conditions. Particulate organic and inorganic carbon production rates for instance decrease at very low external CO2 concentrations. Our model suggests that this effect is caused mainly by reduced HCO3(-) uptake rates, not by CO2 limitation. The often observed decrease in particulate inorganic carbon production rates under Ocean Acidification is explained by a downregulation of cellular HCO3(-) uptake.
Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Am Handelshafen 12, 27570 Bremerhaven, Germany. Electronic address: lena-maria.holtz@awi.de.
Lena-Maria
LM
Holtz
Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Am Handelshafen 12, 27570 Bremerhaven, Germany.
Dieter
D
Wolf-Gladrow
Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Am Handelshafen 12, 27570 Bremerhaven, Germany.
Silke
S
Thoms
D000064:Acclimatization; D002113:Calcification, Physiologic; D002244:Carbon / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism; D002254:Carbonates / Q000737:chemistry*; D002736:Chloroplasts / Q000502:physiology; D003600:Cytosol / Q000378:metabolism; D058087:Haptophyta / Q000502:physiology* / Q000528:radiation effects; D008027:Light; D008954:Models, Biological; D009792:Oceans and Seas; D010788:Photosynthesis; D010839:Phytoplankton / Q000502:physiology / Q000528:radiation effects; D012623:Seawater
D002254:Carbonates; D002245:Carbon Dioxide; D002244:Carbon
CO(2)/carbon uptake; Coccolithophores; Marine carbon cycle; Phytoplankton