Hypoxia has gradually become common in aquatic ecosystems and imposes a significant challenge for fish farming. The loss of equilibrium (LOE), 50% lethal time (LT50), plasma cortisol, glucose, red blood cells (RBC), hemoglobin (Hb), gill histological alteration, and related parameters (lamellar length [SLL] and width [SLW], interlamellar distance [ID], basal epithelial thickness [BET], lamellar surface area [LA], and gill surface area [GSA]); respiratory rate; the proportion of the secondary lamellae available for gas exchange (PAGE); and hypoxia-inducible factor (hif-1α, hif-2α) mRNA expression were determined during progressive hypoxia and reoxygenation (R-0, R-12, R-24 h) to illustrate the underlying physiological response mechanisms in black rockfish Sebastes schlegelii. Results showed that the DO concentration significantly decreased during progressive hypoxia, while DO at LOE and LT50 were 2.42 ± 0.10 mg L⁻¹ and 1.67 ± 0.38 mg L⁻¹, respectively. Cortisol and glucose were significantly increased at LOE and LT50, with the highest levels observed at LT50, and then gradually recovered to normal within reoxygenation 24 h. RBC number and Hb results were like those of glucose. Hypoxia stress resulted in lamellar clubbing, hypertrophy, and hyperplasia. Respiratory frequency significantly increased at LOE and decreased at LT50. Lamellar perimeters, SLL, ID, LA, GSA, and PAGE, significantly increased at LOE and LT50, with the highest values observed at LT50. However, SLW and BET significantly decreased at LOE, LT50, and R-0. These parameters recovered to nearly normal levels at R-24 h. hif-1α mRNAs in gill and liver were significantly upregulated at LOE and LT50, and recovery to normal after reoxygenation 24 h. hif-2α mRNAs in gill was similar to that of hif-1α, whereas hepatic hif-2α mRNAs remained unchanged during hypoxia-reoxygenation. These results indicated that progressive hypoxia stress elevated RBC number, Hb, cortisol, and glucose levels, induced the alteration of gill morphology, increased LA and GSA, stimulated respiratory frequency and PAGE, and upregulated the transcription of hif-1α and hif-2α in gill and liver. Reoxygenation treatment for 24 h alleviated the stress mentioned above effects. These findings expand current knowledge on hypoxia tolerance in black rockfish Sebastes schlegelii.

缺氧在水生生态系统中逐渐变得普遍，并对鱼类养殖提出了重大挑战。平衡丧失 (LOE)、50% 致死时间 (LT50)、血浆皮质醇、葡萄糖、红细胞 (RBC)、血红蛋白 (Hb)、鳃组织学改变和相关参数（板层长度 [SLL] 和宽度 [SLW] ]、层间距离 [ID]、基底上皮厚度 [BET]、层状表面积 [LA] 和鳃表面积 [GSA])；呼吸频率; 可用于气体交换 (PAGE) 的次级薄片的比例；和缺氧诱导因子 ( hif-1α , hif-2α ) mRNA 表达在进行性缺氧和复氧 (R-0, R-12, R-24 h) 期间测定，以说明黑石斑鱼的潜在生理反应机制Sebastes schlegelii。结果表明，在进行性缺氧期间，DO 浓度显着降低，而 LOE 和 LT50 下的 DO 分别为 2.42 ± 0.10 mg L ^-1和 1.67 ± 0.38 mg L ^-1， 分别。皮质醇和葡萄糖在 LOE 和 LT50 时显着增加，在 LT50 时观察到的水平最高，然后在复氧 24 小时内逐渐恢复到正常。RBC 数量和 Hb 结果与葡萄糖类似。缺氧应激导致层状杵状指、肥大和增生。呼吸频率在 LOE 时显着增加，在 LT50 时减少。层状周长、SLL、ID、LA、GSA 和 PAGE 在 LOE 和 LT50 处显着增加，在 LT50 处观察到的最高值。然而，SLW 和 BET 在 LOE、LT50 和 R-0 处显着降低。这些参数在 R-24 小时恢复到接近正常水平。鳃和肝脏中的hif-1α mRNA 在 LOE 和 LT50 时显着上调，并在复氧 24 h 后恢复正常。hif-2α鳃中的 mRNA 与hif-1α 的mRNA 相似，而肝hif-2α mRNA 在缺氧-复氧期间保持不变。这些结果表明，渐进缺氧应力升高RBC数目，血红蛋白，皮质醇，和葡萄糖水平，诱导鳃形态学的改变，增加的LA和GSA，刺激呼吸频率和PAGE，和上调的转录HIF-1α和HIF-2α在鳃和肝脏。复氧处理 24 h 缓解了上述应激效应。这些发现扩展了目前关于黑石斑鱼Sebastes schlegelii耐缺氧性的知识。