Table 1.

Hemolymph parameters of oyster, C. gigas after long-term incubation at control (normocapnia, seawater Pco₂ ~ 0.054 kPa) and elevated CO₂-concentrations (hypercapnia, seawater Pco₂ ~ 0.15 kPa, 26 to 55 days) at 15 ^°C.

Parameter/Group	Control	CO2-incubation
pHe	7.60 ± 0.10	7.09 ± 0.18*
PeCO2 (kPa)	0.15 ± 0.04	0.54 ± 0.19*
PeO2 (kPa)	11.44 ± 3.67	9.43 ± 2.29°
CeCO2 (mM)	1.67 ± 0.11	2.15 ± 0.30*
HCO−3 (mM)	1.28 ± 0.11	1.78 ± 0.29*
Ca2+ (mM)	7.2 ± 0.6	6.2 ± 0.1°
Na+ (mM)	445.4 ± 16.0	422.3 ± 7.4*
K+ (mM)	11.9 ± 0.8	13.0 ± 0.9*

(pH_e: extracellular pH; C_eCO₂: total dissolved inorganic carbon content). Data are means ± SD with N = 7–16 (control) and N = 6–23 (CO₂-incubation).

^*indicates significant differences between control and CO₂-incubated oysters (unpaired t-test, P < 0.05).

^°indicates marginally significant differences between control and CO₂-incubated oysters (unpaired t-test, P = 0.07).