CO₂ mediation of adverse effects of seawater acidification in <i>Calcidiscus leptoporus</i>

Abstract

The coccolithophore Calcidiscus leptoporus (strain RCC1135) was grown in dilute batch culture at CO 2 levels ranging from ∼200 to ∼1600 μ atm. Increasing CO 2 concentration led to an increased percentage of malformed coccoliths and eventually (at ∼1500 μ atm CO 2 ) to aggregation of cells. Carbonate chemistry of natural seawater was manipulated in three ways: first, addition of acid; second, addition of a HCO 3 − /CO 3 2− solution; and third, addition of both acid and HCO 3 − /CO 3 2− solution. The data set allowed the disentangling of putative effects of the different parameters of the carbonate system. It is concluded that CO 2 is the parameter of the carbonate system which causes both aberrant coccolithogenesis and aggregation of cells.