不同溶解氧水平下厚壳贻贝的贝壳开放行为和呼吸代谢

为了探讨溶解氧浓度变化对厚壳贻贝(Mytilus coruscus)摄食和代谢的影响, 分析贝壳开放行为和呼吸代谢的相关关系, 观察测定了 8 mg/L、6 mg/L、4 mg/L、2 mg/L 和 1 mg/L 溶解氧水平下厚壳贻贝贝壳开放程度、滤水率、耗氧率和排氨率, 并计算了氧氮比值。结果显示, 溶解氧浓度在 4 mg/L 及以上水平时, 厚壳贻贝的贝壳持较大程度开放, 而当溶解氧浓度降至 2 mg/L 及以下后, 贝壳逐渐关闭; 溶解氧浓度降至 4 mg/L 后, 贻贝滤水率显著下降; 溶解氧浓度在 2~8 mg/L 间, 贻贝耗氧率无显著变化, 降至 1 mg/L 后, 耗氧率显著下降; 排氨率与滤水率和耗氧率呈相反趋势, 溶解氧浓度降至 2 mg/L 后, 贻贝排氨率显著上升; 降至 4 mg/L 后, 氧氮比值显著下降; 贝壳开放程度与滤水率、耗氧率之间呈正相关关系。研究表明, 厚壳贻贝可以适应一定范围内溶解氧浓度的波动, 保持机体代谢水平相对稳定; 当环境溶解氧降至 1 mg/L 以下, 机体无法再维持正常的代谢, 厚壳贻贝部分关闭贝壳, 以降低能量消耗, 应对低氧胁迫。本研究可为厚壳贻贝低氧适应机制研究和养殖提供参考。

Shell valve opening behavior and metabolism of Mytilus coruscus un-der different oxygen concentrations

To explore the effects of variations in dissolved oxygen concentrations on the feeding and metabolism of the mussel Mytilus coruscus and analyze the relationship between shell opening behavior and respiratory metabolism, we observed and measured the shell valve opening degree and rates of filtration, oxygen consumption, and ammonia excretion of M. coruscus exposed to 8, 6, 4, 2, and 1 mg/L dissolved oxygen and calculated the O:N ratio. The results revealed the following: at oxygen concentrations greater than 4 mg/L, the shell valve of M. coruscus mainly remained opened but gradually closed when the oxygen concentration decreased to below 2 mg/L; when the oxygen concentration decreased to 4 mg/L, the filtration rate decreased significantly; and the oxygen consumption remained stable when the oxygen concentration was between 2 and 8 mg/L but declined significantly when the concentration decreased to 1 mg/L. The ammonia excretion rate showed an opposite tendency, increasing significantly when the oxygen concentration decreased to 2 mg/L, and the O:N ratio significantly decreased when the oxygen concentration decreased to 4 mg/L. Furthermore, a positive relationship was found between the shell valve opening degree and the rates of filtration and oxygen consumption. The findings of this study indicate that M. coruscus can adapt to fluctuations in dissolved oxygen concentrations within a certain range and maintain a relatively stable metabolic level. However, in environments where dissolved oxygen concentrations decrease to below 1 mg/L, these mussels are unable to maintain normal metabolism and respond to hypoxic stress by closing the shell valve to reduce energy consumption. These observations can provide a reference for investigating the hypoxia adaptive mechanism and farming of M. coruscus.