We examined hemolymph O_2 partial pressure (Po_2), pH, total CO_2 content (Tco_2), CO_2 partial pressure (Pco_2) and bicarbonate concentration ([HCO_3^-]) in order to evaluate the acid–base balance of the densely lamellated oyster Ostrea denselamellosa in normoxic conditions. Hemolymph was collected anaerobically through a cannula inserted into the adductor muscle of O. denselamellosa. The mean values of hemolymph Po_2, pH, and Tco_2 were 64.7 torr, 7.576 and 1.22 mM/l, respectively. Using αco_2 and pKapp determined in this study, the hemolymph Pco_2 and [HCO_3^–] were calculated as 1.10 torr and 1.17 mM/l, respectively. These hemolymph properties were compared with those of other marine bivalves. Ostrea denselamellosa seemed to efficiently discharge CO_2 and maintain high hemolymph pH in normoxic conditions.
Ostrea denselamellosa
hemolymph acid-base balance
normoxia
apparent dissociation constant of carbonic acid
CO_2 partial pressure
bicarbonate ion