不同溶氧水平对褐牙鲆幼鱼呼吸行为和血液指标的影响

通过控制每个水族箱的水流供应,将溶解氧(DO,Mean±SE)分别控制在(2.24±0.24) mg/L、(3.14±0.24) mg/L、(4.27±0.18)mg/L、(5.38±0.25)mg/L、(6.94±0.14) mg/L,研究其对养殖40d的褐牙鲆(Paralichth ys olivaceus)幼鱼呼吸行为和血液指标的影响.实验结束时,幼鱼的鳃重和体重比值未出现明显差异,只在最高溶解氧含量处理组略微低于其余处理组.平均呼吸频率随溶解氧含量的下降明显提高,每次呼吸鳃盖的伸展幅度随溶解氧含量的下降明显加大,头部上抬的鱼的比例随溶解氧含量的降低而增加.血液中血红细胞含量、血红蛋白含量、单个红细胞血红蛋白含量均呈现与溶解氧含量负相关趋势.单个红细胞体积未表现出与溶解氧的明显关系,只有溶解氧为3.14 mg/L的处理体积明显大于其他处理.4 mg/L左右的溶解氧含量对褐牙鲆幼鱼而言可能是溶解氧正常水平与缺氧的临界范围,而呼吸频率、鳃盖伸展幅度和抬头比例的大幅提高可以作为水体缺氧的行为判断依据.褐牙鲆幼鱼为适应溶解氧含量下降,血液摄取和携带氧气的能力提高.

Effects of Dissolved Oxygen Content on Respiratory Behavior and Blood Parameters of Juvenile Paralichthys olivaceus

Dissolved oxygen content (DO, Mean±SE) of the aquarium was controlled at (2.24±0.24) mg/L, (3.14±0.24) mg/L, (4.27±0.18) mg/L, (5.38±0.25) mg/L, and (6.94±0.14) mg/L, respectively, by limiting the seawater supply to the aquarium.The effects of dissolved oxygen content on respiratory behavior and blood parameters of juvenile Paralichthys olivaceus were investigated.The ratio of gill weight to body weight did not appeared significant difference at the end of the experiment and it was slightly lower in P.olivaceus supplied with the highest DO than other treatment.The average ventilation frequency (VF) and the opercular stretching grade (OSG) increased as DO declined. The proportion of head raising (PHR) of fish was negatively correlated to DO.Red blood cell amount (RBC), haemoglobin concentration (Hb), and red blood cell hemoglobin (MRBCH) were negatively correlated to DO.No significant correlation between red blood cell volume (RBCV) and DO was observed, but RBCV in treatment with (3.14±0.24) mg/L DO was significantly greater than other treatment.It could be concluded that the critical DO for juvenile P.olivaceus may be about 4 mg/L.A great elevation of VF, OSG, and PHR could be used as a criterion for hypoxia.The juvenile P.olivaceus could adapt the descending of DO by enhancing the capacity of oxygen taking and carrying.