We examined hemolymph O2 partial pressure (Po2), pH, total CO2 concentration (Tco2), CO2 partial pressure (Pco2), and bicarbonate concentration (HCO3–) to evaluate the acid–base balance of the winged pearl oyster Pteria penguin under normoxic condition. Hemolymph was collected anaerobically from the adductor muscle. Mean values for hemolymph Po2, pH and Tco2 were 73.4 torr, 7.598 and 2.40 mM/L, respectively. Hemolymph Pco2was calculated using the rearranged Henderson–Hasselbalch equation, yielding 1.83 torr and a HCO3– of 2.33 mM/L. The non-bicarbonate buffer value (hemolymph pH–HCO3– relational expression slope) was 1.99 slykes, higher than that of other marine bivalves. Thus, the winged pearl oyster hemolymph has a comparatively greater nonbicarbonate buffering capacity
Handa et al. (Fri,) studied this question.