The response of the coccolithophore Emiliania huxleyi to rising CO2 concentrations is well documented in acclimated cultures where cells are exposed to the CO2 treatments for several generations prior to the experiment. Extended acclimation times have generally been applied because of the lack of information about time required to reach a new physiological “equilibrium” (acclimation) in response to CO2-induced changes in seawater carbonate chemistry. Here we show that Emiliania huxleyi‘s short-term response (hours to 1 day) to increasing CO2 is similar to that obtained with acclimated cultures under comparable conditions in earlier studies. At CO2 concentrations ranging from glacial (190 μatm) to projected year 2100 (750 μatm) levels, calcification decreased and organic carbon fixation increased within 8 h after exposing the cultures to the changed CO2 conditions. This led to a decrease in the ratio of CaCO3 to organic carbon production. Our results show that Emiliania huxleyi rapidly alters the rates of various essential processes in response to changes in seawater carbonate chemistry, establishing a new physiological (acclimation) “state” within a matter of hours. If this relatively rapid response applies to other phytoplankton species, it may simplify interpretation of studies with natural communities (e.g. mesocosm studies and ship-board incubations), where often it is not feasible to allow for a pre-conditioning phase before starting experimental incubations.
Barcelos e Ramos, J., Müller, M. N. & Riebesell, U., 2009. Short-term response of the coccolithophore Emiliania huxleyi to abrupt changes in seawater carbon dioxide concentrations. Biogeosciences Discussions 6(3):4739-4763. Article.
