CO₂ emissions from human activities are increasing, resulting in greater rates of change in the oceans, exceeding any other event in geological and historical records over the past 300 million years. Oceans are warming and pH levels are decreasing. Marine organisms will need to respond to multiple stressors and the potential consequences of global change-related effects in fish needs to be investigated. Fish are affected by many biotic and abiotic environmental variables, including temperature and CO₂ fluctuations, and it is therefore critical to investigate how these variables may affect physiological and biochemical processes. We investigated the effects of elevated CO₂ levels (pH of 8.0, which served as a control, or 7.6, which is predicted for the year 2100) combined with exposure to different temperatures (5, 10, 12, 14, 16, and 18 °C) in the Atlantic halibut (Hippoglossus hippoglossus) during a three month experiment. Since regulation of reactive oxygen species (ROS) is crucial for physiological processes the focus was on the antioxidant defense system and we assessed the effects on catalytic activities of antioxidant enzymes (SOD, CAT, GR, GST, GPx). In addition we also analyzed effects on cholinesterase enzymes (AChE and BChE), and CYP1A enzyme activities (EROD). The treatments resulted in oxidative stress, and damage was evident in the form of protein carbonyls which were consistently higher in the elevated CO₂-treated fish at all temperatures. Analyses of antioxidant enzymes did not show the same results, suggesting that the exposure to elevated CO₂ increased ROS formation but not defences. The antioxidant defense system was insufficient, and the resulting oxidative damage could impact physiological function of the halibut on a cellular level.

人类活动产生的CO ₂排放量正在增加，导致海洋变化率更高，超过了过去3亿年的地质和历史记录中的任何其他事件。海洋正在变暖，pH值正在下降。海洋生物将需要应对多种压力，并且需要调查与鱼类有关的全球变化相关影响的潜在后果。鱼类受到许多生物和非生物环境变量的影响，包括温度和CO ₂波动，因此研究这些变量如何影响生理和生化过程至关重要。我们调查了CO ₂升高的影响大西洋大比目鱼的最高水平（pH值8.0，作为对照，而7.6则预测到2100年）与暴露在不同温度（5、10、12、14、16和18°C）下的温度相结合（在三个月的实验中，河马（Hippoglossus hippoglossus）。由于活性氧（ROS）的调节对于生理过程至关重要，因此重点是抗氧化剂防御系统，我们评估了抗氧化剂酶（SOD，CAT，GR，GST，GPx）对催化活性的影响。此外，我们还分析了对胆碱酯酶（AChE和BChE）和CYP1A酶活性（EROD）的影响。这些处理导致氧化应激，并且损害以蛋白质羰基形式明显，在升高的CO ₂中始终较高处理过的鱼在所有温度下。抗氧化剂酶的分析未显示出相同的结果，表明暴露于升高的CO _2会增加ROS的形成，但不能防御。抗氧化剂的防御系统不足，所产生的氧化损伤可能在细胞水平上影响大比目鱼的生理功能。