Production of calcium carbonate by marine calcifying organisms has been shown to decrease under increasing CO2. This effect appears to be driven by a decrease in [CO32-]. The modelling study here described aims at investigating whether the success of a marine calcifying phytoplankton species, the coccolithophore Emiliania huxleyi, may be tied to [CO32-]. The work highlights the complex interactions between the carbonate system variables and spring blooms, and the possibility of a link to the competition between calcifying vs. non-calcifying species on the Bering Sea shelf. We find that the strong seasonal cycle in [CO32-] is driven primarily by carbon drawdown during spring blooms. The interesting outcome of this work is the fact that E. huxleyi bloom timings always coincide with periods of high [CO32-], which is consistent with studies showing coccoliths malformations and a slowdown in calcification at low [CO32-]. Whether the condition of high [CO32-] can be considered a crucial ecological factor for the success of E. huxleyi, however, remains an open and important question needing further investigation. (c) 2005 Elsevier B.V. All rights reserved.