Determinants of the PIC:POC response in the coccolithophore Emiliania huxleyi under future ocean acidification scenarios

We use a meta-analysis to quantify the response of Emiliania huxleyi particulate inorganic carbon (PIC) to particulate organic carbon (POC) ratio under different laboratory conditions and changes in carbonate chemistry. There is an overarching trend of decreasing PIC : POC across all ecotypes irrespective of the strain, isolation date, isolation location, and method of acidification. The variability about this overall trend is explained by the different nutrient and light regimes used in each experiment, but there is no evidence for a strain-specific response that might be expected if strains had adapted to the average environmental conditions at the locations from which the strain was isolated; indeed, each strain shows a comparably broad physiological window. We propose that E. huxleyi PIC : POC exhibits a plastic response to carbonate conditions that can be predicted by the seawater concentrations of aqueous CO2, total alkalinity, and phosphate conditions. This relationship now requires field validation as well as longer-term studies of E. huxleyi response to variable environmental conditions.