MEPS 129:307-312 (1995)  -  doi:10.3354/meps129307

A simple expression enables prediction of the effect of photosynthetic and calcifying systems on air-sea CO₂ exchange at all spatial scales (from organism to ecosystem). Input data are: gross primary production (P_g), respiration (R), net calcification (G) and the ratio of CO₂ released to CaCO₃ precipitated (Psi); the output is the amount of dissolved inorganic carbon (F_CO2) which needs to be exchanged with the atmosphere to balance biologically mediated changes in the concentration of dissolved inorganic carbon in an open sea water system: F_CO2 = -P_g + R + PsiG. Coral reef data were used in the model to illustrate the relative influence of organic and inorganic carbon metabolism on ocean-atmosphere CO₂ cycling. A coral reef comprised of calcareous and non-calcareous organisms can be shown to act as a sink for atmospheric CO₂ when excess (= net) production is high and CaCO₃ precipitation is low. These characteristics are not typical of actively developing reef systems which typically exhibit a nearly balanced organic carbon metabolism (P_g/R = ca 1) and relatively high rates of calcification. In these circumstances, reef communities can be expected to cause CO₂ evasion to the atmosphere. This prediction is confirmed by the only existing measurement of air-sea CO₂ flux in a coral reef system.

Community metabolism . Primary production . Respiration . Calcification . Air-sea CO₂ flux . Coral reefs