溶氧水平对瓦氏黄颡鱼幼鱼静止耗氧率和临界游泳运动能力的影响

摘要

为了研究瓦氏黄颡鱼(Peltebagrus vachelli)在不同溶氧水平(DO)下的游泳运动能力、限制性机制及能量适应对策,在25℃分别对不同溶氧水平(125％、100％、75％、50％和25％空气饱和度)条件下瓦氏黄颡鱼幼鱼静止耗氧率、临界游泳速度(Ucrit)、活跃耗氧率进行了测定.研究发现瓦氏黄颡鱼的静止耗氧率随溶氧水平下降而显著下降(P＜0.05),其临界氧浓度点([O2]crit)为14.52％空气饱和度(1.16 mg/L).当溶氧水平从100％下降到25％空气饱和度时,其活跃耗氧率随溶氧的下降而显著下降(P＜0.05)；当溶氧从75％下降到25％空气饱和度时,其临界游泳速度随溶氧的下降而显著下降(P＜0.05)；但是在超饱和氧(125％空气饱和度)条件下,其临界游泳速度与活跃耗氧率均没有显著提升；在25％空气饱和度条件下的游泳转化效率显著低于其余溶氧组条件下的游泳转化效率(P＜0.05).研究结果提示:在低氧条件下,瓦氏黄颡鱼的临界游泳速度受中心的心鳃系统的限制,而在常氧条件下,受外周的运动系统(肌肉组织)的限制.%To test the swimming performance,locomotive limiting factors and metabolic adaptive strategy of darkbarbel catfish Peltebagrus vachelli under different dissolved oxygen levels (DO),the effects of DO (125％,100％,75％,50％ and 25％ air saturation) on resting oxygen consumption rate (MO2),critical swimming speed (Ucrit) and MO2 at different swimming speeds up to Ucrit were investigated in juvenile darkbarbel catfish at 25℃.Resting MO2 decreased significantly with DO (P＜0.05),and the critical DO point ([O2]crit) for resting MO2 was 14.52％ air saturation (1.16 mg/L).The active MO2 decreased significantly with the decrease of DO from 100％ to 25％ air saturation (P＜0.05); the Ucrit decreased significantly when DO fell below 75％ air saturation (P＜0.05); neither Ucrit nor active MO2 showed any elevation under hyperoxic conditions (125％ air saturation); and the cost of transport (COT) was significantly lower under 25％ air saturation than that of other groups at corresponding swimming speeds (P＜0.05).These results suggested that the swimming performance of darkbarbel catfish was limited by the cardio-respiratory system under hypoxia,while it was limited by the peripheral locomotory organs and musculature under normoxia.