We examined hemolymph pH, total CO_2 content (Tco_2, mM/l), CO_2 partial pressure (Pco_2, mmHg) and bicarbonate concentration ([HCO_3^-], mM/l) in order to evaluate the acid-base balance of the noble scallop Mimachlamys nobilis in normoxic conditions. Hemolymph was collected anaerobically through a cannula after catheterization of the adductor muscle. The mean values of hemolymph pH and Tco_2 were 7.442 and 1.50 mM/l, respectively. Using the CO_2 solubility coefficient and apparent dissociation constant of carbonic acid determined in this study, Pco_2 and [HCO_3^-] were calculated as 1.55 mmHg and 1.44 mM/l, respectively. These values were in same range as those of the hemolymph of other marine bivalves of Mytiloida, Pterioida and Ostreoida.
Mimachlamys nobilis
cannulation
hemolymph
acid-base balance
Pco_2
dissociation constant of carbonic acid