Aerobic performance of two tropical cephalopod species unaltered by prolonged exposure to projected future carbon dioxide levels

Abstract [Related Publication]: Squid and many other cephalopods live continuously on the threshold of their environmental oxygen limitations. If the abilities of squid to effectively take up oxygen are negatively affected by projected future carbon dioxide (CO₂) levels in ways similar to those demonstrated in some fish and crustaceans, it could affect the success of squid in future oceans. While there is evidence that acute exposure to elevated CO₂ has adverse effects on cephalopod respiratory performance, no studies have investigated this in an adult cephalopod after relatively prolonged exposure to elevated CO₂ or determined any effects on aerobic scope. Here, we tested the effects of prolonged exposure (≥20% of lifespan) to elevated CO₂ levels (~1000µatm) on the routine and maximal oxygen uptake rates, aerobic scope, and recovery time of two tropical cephalopod species, the two-toned pygmy squid, Idiosepius pygmaeus and the bigfin reef squid, Sepioteuthis lessoniana. Neither species exhibited evidence of altered aerobic performance after exposure to elevated CO₂ when compared to individuals held at control conditions. The recovery time of I. pygmaeus under both control and elevated CO₂ conditions was less than one hour; whereas, S. lessoniana required approximately eight hours to recover fully following maximal aerobic performance. This difference in recovery time may be due to the more sedentary behaviours of I. pygmaeus. The ability of these two cephalopod species to cope with prolonged exposure to elevated CO₂ without detriment to their aerobic performance suggests they may be resilient to an increasingly high CO₂ world.The full methodology is available in the Open Access publication from the Related Publications link below.

摘要【相关文献】：枪乌贼与多数其他头足类动物始终生存于其环境氧耐受阈值的临界状态。若枪乌贼的有效摄氧能力如部分鱼类和甲壳类动物中已证实的那样，会受到预测的未来二氧化碳（CO₂）水平的负面影响，则可能影响其在未来海洋中的生存适应性。尽管已有证据表明，急性暴露于高浓度CO₂环境会对头足类动物的呼吸机能产生不利影响，但目前尚无研究针对成年头足类动物开展相对长期的高CO₂暴露实验，亦未探明其对有氧代谢范围（aerobic scope）的影响。本研究针对两种热带头足类动物——双斑矮鱿鱼（Idiosepius pygmaeus）与大鳍礁鱿鱼（Sepioteuthis lessoniana），探究了长期暴露（≥其寿命的20%）于约1000微大气压（µatm）高CO₂水平环境下，其常规摄氧率、最大摄氧率、有氧代谢范围以及恢复时长的变化情况。与对照组养殖个体相比，两种受试动物均未表现出高CO₂暴露后有氧代谢机能发生改变的迹象。双斑矮鱿鱼在对照组与高CO₂暴露组中的恢复时长均不足1小时；而大鳍礁鱿鱼在达到最大有氧代谢状态后，完全恢复约需8小时。二者恢复时长的差异，可能源于双斑矮鱿鱼更为静息的生活习性。这两种头足类动物能够在长期暴露于高CO₂环境的情况下未出现有氧代谢机能受损的情况，表明它们或可在CO₂水平不断升高的未来海洋中保持生存韧性。完整实验方法可通过下方相关文献链接指向的开源出版物获取。