Shellfish CO2 excretion is modulated by seawater carbonate chemistry but largely independent of pCO2

Four species of shellfish, blue mussel ( Mytilus galloprovincialis ), Pacific abalone ( Haliotis discus hannai ), zhikong scallops ( Chlamys farreri ), and Pacific oyster ( Crassostrea gigas ), were exposed to decoupled carbonate system variables to investigate the impacts of different seawater carbonate parameters on the CO 2 excretion process of mariculture shellfish. Six experimental groups with two levels of seawater pH (pH 8.1 and pH 7.7) and three levels of total alkalinity (TA = 1000, 2300, and 3600 μmol/kg, respectively) were established, while pH 8.1 and TA = 2300 μmol/kg was taken as control. Results showed that the CO 2 excretion rates of these tested shellfish were significantly affected by the change in carbonate chemistry ( P 0.05) was found; however, a significant correlation ( P