アコヤガイPinctada fucata martensii, マガキ Crassostrea gigas，ヒオウギ Mimachlamys nobilis から採取したヘモリンパ液を用いて二酸化炭素溶解度係数 (αco_2，µM/L/torr) に及ぼす温度 (T，°C) の影響について調べ，αco_2 とT の関係を明らかにした。アコヤガイで得た関係式は，αco_2 = 76.88145 − 2.62637 · T + 0.036203 · T^2 であった。同様にマガキとヒオウギはαco_2 = 94.2109 – 3.6252 · T + 0.0554 · T^2 (マガキ)，αco_2 = 70.4591 – 1.5253 · T + 0.0103 · T^2 (ヒオウギ) だった。これら３種のαco_2 の分布を比較すると統計的有意差は認められなかったことから，３種のαco_2 と温度の全ての結果に対して多項式回帰を適用し，以下の関係式を得た。　αco_2 = 182.3717 – 24.3932 · T + 1.6396 · T^2 – 0.0492 · T^3 + 0.000536 · T^4。この式により，種が異なっても，任意の温度で海産二枚貝のαco_2 を容易に得られ，酸塩基平衡，二酸化炭素動態および呼吸生理の評価に有効と考えられる。

We investigated the oxygen and acid–base status of the noble scallop Mimachlamys nobilis during air exposure for 24 h. The hemolymph of noble scallop was collected from the adductor muscle, and O_2 partial pressure (Po_2), pH, CO_2 partial pressure (Pco_2), and bicarbonate ion concentration ([HCO_3^–]) were examined during air exposure. Hemolymph Po_2 decreased from 69.5 torr (mean value) to 46.3 torr during air exposure for 6 h, and reached to 19.0 torr after 24 h. The hemolymph Po_2 of air-exposed noble scallops decreased gradually and caused progressive hypoxemia by hypoventilation of the ctenidium. Air-exposed noble scallops showed a reduction in pH and elevation of Pco_2 and [HCO_3^–] of the hemolymph. In air-exposed noble scallops, the hemolymph pH decreased from 7.460 to 7.045 at 6 h and to 6.348 at 24 h. The hemolymph Pco_2 increased from 1.30 torr to 5.05 torr at 6 h and to 56.6 torr at 24 h during air exposure. The [HCO_3^–] increased from 1.26 mM/L to 1.88 mM/L at 6 h and to 4.19 mM/L at 24 h. N32From these results, in the first 6 h of air exposure, noble scallops mainly underwent respiratory acidosis by excess accumulation of CO_2 due to hypoventilation. Meanwhile, after 24 h of air exposure, noble scallops showed mainly metabolic acidosis partially compensated by mobilized [HCO_3^–] from the shell.