Strain-specific responses of Emiliania huxleyi to changing seawater carbonate chemistry

Abstract. Four strains of the coccolithophore E. huxleyi (RCC1212, RCC1216, RCC1238, RCC1256) were grown in dilute batch culture at four CO₂ levels ranging from ~200 μatm to ~1200 μatm. Growth rate, particulate organic carbon content, and particulate inorganic carbon content were measured, and organic and inorganic carbon production calculated. The four strains did not show a uniform response to carbonate chemistry changes in any of the analysed parameters and none of the four strains displayed a response pattern previously described for this species. We conclude that the sensitivity of different strains of E. huxleyi to acidification differs substantially and that this likely has a genetic basis. We propose that this can explain apparently contradictory results reported in the literature.