Coccolithophores and the biological pump: responses to environmental changes

Coccolithophores, which are considered to be the most productive calcifying or-ganisms on earth, play an important role in the marine carbon cycle. The forma-tion of calcite skeletons in the surface layer and their subsequent sinking to depth modifies upper-ocean alkalinity and directly affects air/sea CO2 exchange. Recent work indicates that the productivity and distribution of coccolithophores are sen-sitive to CO2-related changes in environmental conditions, both directly through acidification of surface seawater and indirectly through increasing upper-ocean thermal stratification. To assess possible responses of this group we examine the physiology and ecology of coccolithophores with regard to expected environ-mental changes. Potential feedbacks to atmospheric CO2 increase, as could arise from changes in photosynthesis and calcification as well as from a shift in the dominance of coccolithophores, may be crucial when trying to forecast future cli-mate change