Is there any relationship between phytoplankton seasonal dynamics and the carbonate system?

Abstract

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.