摄食和饥饿对大口黑鲈游泳运动能力和低氧耐受的影响

为了研究摄食和饥饿对鱼类游泳运动能力和低氧耐受的影响; 以大口黑鲈(Micropterus salmoides)为对象, 在25℃下, 测定对照组(禁食2d)、摄食组(摄食后3h)和饥饿组(禁食16d)实验鱼的日常代谢率(RMR)、活跃代谢率(AMR)、代谢范围(MS)、临界游泳速度(U_crit)、临界氧压(P_crit)和失去平衡点(LOE)。研究显示摄食后实验鱼RMR显著提升, AMR没有显著变化, 而MS和U_crit显著下降(P<0.05); 饥饿后实验鱼RMR、AMR和MS均没有显著变化, 而U_crit显著下降(P<0.05); 摄食后实验鱼P_crit显著上升, 溶解氧(DO)高于P_crit时的代谢率(MR)与DO之间的关系的斜率显著大于对照组所对应的斜率, 而LOE没有变化(P<0.05); 饥饿后实验鱼P_crit和LOE均没有显著变化, 而DO 低于P_crit时的MR与DO之间的关系的斜率显著小于对照组所对应的斜率(P<0.05)。结果表明, 摄食削弱大口黑鲈游泳运动能力是因为“心鳃”系统对其有氧代谢能力的限制; 饥饿后大口黑鲈游泳运动能力下降可能与其无氧代谢能力下降相关; 摄食削弱大口黑鲈的低氧耐受, 而饥饿后其低氧耐受有所增强, 但大口黑鲈低氧耐受总体趋于保守。

FEEDING AND FASTING ON SWIMMING PERFORMENCE AND HYPOXIA TOLERANCE OF MICROPTERUS SALMOIDES

To evaluate the effects of feeding and fasting on swimming performance and hypoxia tolerance of fish, we tested the routine metabolic rate (RMR), active metabolic rate (AMR), metabolic scope (MS), critical swimming speed (U_crit), critical oxygen pressure (P_crit) and the point of loss of equilibrium (LOE) of largemouth bass (Micropterus salmoides) at 25℃. The fish were divided into 3 groups which include control group (fasting for 2d), feeding group (3h after feeding) and fasting group (fasting for 16d). The results showed that the RMR increased, but the MS and U_crit decreased after feeding (P<0.05). There was no change in AMR between feeding group and control group (P>0.05). There was no change in RMR, AMR and MS between fasting group and control group (P>0.05). The U_crit of fish was decreased after fasting (P<0.05). The P_crit was higher in feeding group than that in control group (P<0.05). When the dissolved oxygen level was higher than the P_crit, the slope of the metabolic rate (MR) and dissolved oxygen (DO) in feeding group was higher than that in control group (P<0.05). There was no difference in LOE between feeding group and control group (P<0.05); There was no difference in P_crit and LOE between fasting group and control group (P<0.05). However, when the dissolved oxygen level was below the P_crit, the slope of the MR and DO in fasting group was lower than that in control group (P<0.05). The results showed that the weakening of swimming performance of largemouth bass in feeding group was caused by the limitation of its cardiobranchial system on its aerobic metabolism ability. After fasting, the weakening of swimming performance of largemouth bass may be related to the decline of anaerobic metabolism ability; Feeding weakens the hypoxic tolerance of largemouth bass, while fasting enhances its hypoxic tolerance. However, the hypoxic tolerance of largemouth bass is conservative.