不同溶氧水平下锦鲫的运动和代谢适应对策

The Locomotive and Metabolic Strategies of Goldfish Under Different Dissolved Oxygen Level

为考查广氧性鱼类锦鲫(Carassius auratus)在不同水体溶氧(DO)水平下的运动和能量代谢适应对策,在25℃对水体DO分别为0.5、1、2、4 mg.L-1以及接近100%饱和溶氧浓度的8 mg.L-1水平下锦鲫幼鱼静止代谢率(RMR)、活跃代谢率(AMR)、临界游泳速度(Ucrit)及不同游泳速度下的单位位移能量消耗(COT)进行了测定。研究发现锦鲫的Ucrit和AMR均随着DO的下降而呈下降趋势,各处理组均有显著差异(p<0.05),两者在低DO端即4～1mg.L-1下降更为剧烈,且AMR下降速率明显大于Ucrit;RMR在DO从8～1 mg.L-1时没有显著变化,但1 mg.L-1以下随DO的下降线性下降(p<0.05);各实验处理组锦鲫随游泳速度的上升代谢率上升;低DO实验组(0.5、1和2mg.L-1实验组)各游泳速度下COT无显著差异,而高DO实验组(4和8 mg.L-1实验组)COT随游泳速度的上升而显著上升,消除RMR影响后各实验组单位位移净能量消耗(COTnet)随游泳速度上升均显著上升(p<0.05);在较低的游泳速度下,较低的DO实验组往往比同一游泳速度下的较高DO实验组锦鲫有更高的能量利用效率(低COT值,p<0.05),但随着游泳速度上升不再有该趋势。研究提示锦鲫在不同DO水平下采取不同的运动和能量代谢对策以适应不同环境溶氧条件。

To investigate the locomotive and metabolic adaptive strategy of euroxybiotic goldfish （ Carassius auratus） under different dissolved oxygen level （DO）, we measured the resting metabolic rate （RMR）, active metabolic rate （AMR）, critical swimming speed （ Ucrit ） and cost of transport （COT） at different swimming speed of juvenile experimental fish （ 6.75 - 13.70 g, n = 49 ） maintained at water temperature of （25.0±1.0） ℃ under DO of 0.5, 1, 2, 4 and 8 mg · L^- 1 （ close to 100% saturation）. The results are discovered in that both Ucrit and AMR decreased profoundly with DO and there are significant differences among all treatment groups （p 〈0.05）, but both variables decrease more profoundly within lower DO range and the values of AMR decrease more profoundly than those of Ucrit. However, RMR remain unchang with DO decreased from 8 to 1 mg · L^- 1 and linearly decreased with DO when it is below 1 mg · L^-1. The metabolic rate exponentially increases with swimming speed in all experimental groups. The COT does not vary with swimming speed in lower DO groups （0.5, 1 and 2mg · L^- 1 experimental groups） while it increases with swimming speed at higher DO groups （4 and 8 mg · L^- 1 experimental groups）. After removing the energy component of RMR from COT, the COT., increases with swimming speed in all experimental DO groups. As in the same swimming speed, COT of lower DO groups usually are lower than those of higher DO groups in lower swimming speed range. Moreover, such difference vanishes when swimming speed goes higher. The study shows that goldfish may adopt different locomotive and metabolic strategies under different ambient DO level.