Dissolved oxygen (DO) saturation in the water is a crucial factor in fish performance and welfare. Exposure to low DO can affect a wide variety of functions such as metabolic rate and physiological adaptations including hematological, hormonal, biochemical and osmoregulatory alterations in blood and plasma. In the present study European sea bass, Dicentrarchus labrax and gilthead seabream, Sparus aurata were reared for approximately 3 months at different levels of DO saturation, namely 40–60%, 60–80% and 80–100% at a temperature of 26.5 °C. Both species showed reduced performance at the lowest DO regime compared to the highest, as well as a reduced aerobic capacity as indicated by the aerobic scope and the post-stress lactate concentrations. Blood samples were collected before and after exposure to an acute chasing and confinement stress. Hematocrit, hemoglobin and mean corpuscular hemoglobin concentration were affected by DO saturation in Dicentrarchus. labrax but not in parus aurata. Cortisol levels in fish plasma and scales were similar between different DO regimes in both species, while in plasma it was increased after exposure to acute stress. Moreover, in both species post-stress levels of osmolality and lactate were higher at the lowest DO examined, indicative of osmoregulatory imbalance. Based on multivariate analysis glucose and lactate were highly affected by acute stress in low oxygen saturation in D. labrax, while osmolality was mostly affected in S. aurata. Overall, this study provided a detailed insight in the effects of DO in the physiology of D. labrax and S. aurata.

水中溶解氧 (DO) 饱和度是影响鱼类性能和福利的关键因素。暴露于低 DO 会影响多种功能，例如代谢率和生理适应，包括血液和血浆中的血液、激素、生化和渗透压调节变化。在本研究中，欧洲鲈鱼、Dicentrarchus labrax和金头鲷、Sparus aurata在 26.5 °C 的温度下，在不同的 DO 饱和度（即 40-60%、60-80% 和 80-100%）下饲养约 3 个月。与最高溶解氧相比，两种物种在最低溶解氧状态下表现出降低的性能，以及有氧范围和应激后乳酸浓度表明的有氧能力降低。在暴露于急性追逐和限制压力之前和之后收集血样。红细胞比容、血红蛋白和平均红细胞血红蛋白浓度受Dicentrarchus 中溶解氧饱和度的影响。labrax但不在parus aurata. 两种物种的不同溶解氧状态下，鱼血浆和鳞片中的皮质醇水平相似，而血浆中的皮质醇水平在暴露于急性应激后增加。此外，在这两个物种中，在所检查的最低 DO 时，压力后渗透压和乳酸水平都较高，这表明渗透压调节失衡。多变量分析表明，低氧饱和度下急性应激对D. labrax的葡萄糖和乳酸影响较大，而S. aurata对渗透压的影响最大。总体而言，这项研究详细了解了 DO 对D. labrax和S. aurata生理学的影响。