Coral reef calcification: carbonate, bicarbonate and proton flux under conditions of increasing ocean acidification.

Data on calcification rate of coral and crustose coralline algae were used to test the proton flux model of calcification. There was a significant correlation between calcification (G) and the ratio of dissolved inorganic carbon (DIC) to proton concentration ([DIC] : [H(+)] ratio). The ratio is tightly correlated with [CO3(2-)] and with aragonite saturation state (Ωa). An argument is presented that correlation does not prove cause and effect, and that Ωa and [CO3(2-)] have no basic physiological meaning on coral reefs other than a correlation with [DIC] : [H(+)] ratio, which is the driver of G.