Fisheries and Maritime Museum, DK-6710 Esbjerg V, Denmark.
J Fish Biol. 2011 Oct;79(4):969-79. doi: 10.1111/j.1095-8649.2011.03069.x. Epub 2011 Sep 2.
The objective of this study was to identify behavioural adjustments leading to avoidance of hypoxia. Using the oxygen-sensitive species rainbow trout Oncorhynchus mykiss as a model, individual fish were recorded while moving freely between two sides of a test arena: one with normoxia and one with stepwise progressive hypoxia [80-30% dissolved oxygen (DO) air saturation]. The results demonstrated a gradual decrease in the total time spent in hypoxia starting at 80% DO air saturation. At this DO level, the avoidance of hypoxia could not be attributed to changes in spontaneous swimming speed, neither in normoxia nor in hypoxia. Reducing the DO level to 60% air saturation resulted in decreased spontaneous swimming speed in normoxia, yet the number of trips to the hypoxic side of the test arena remained unchanged. Moreover, data revealed increased average residence time per trip in normoxia at DO levels ≤60% air saturation and decreased average residence time per trip in hypoxia at DO levels ≤50% air saturation. Finally, the spontaneous swimming speed in hypoxia increased at DO levels ≤40% air saturation and the number of trips to hypoxia decreased at the 30% DO air saturation level. Thus, avoidance of the deepest hypoxia was connected with a reduced number of trips to hypoxia as well as decreased and increased spontaneous swimming speed in normoxia and hypoxia, respectively. Collectively, the data support the conclusions that the mechanistic basis for avoidance of hypoxia may (1) not involve changes in swimming speed during mild hypoxia and (2) depend on the severity of hypoxia.
本研究的目的是确定导致避免缺氧的行为调整。使用对氧气敏感的物种虹鳟鱼 Oncorhynchus mykiss 作为模型，当鱼在测试区域的两侧自由移动时，对个体鱼进行记录：一侧是常氧，另一侧是逐步递增的缺氧[80-30%溶解氧（DO）空气饱和度]。结果表明，从 80% DO 空气饱和度开始，总在缺氧环境中停留的时间逐渐减少。在这个 DO 水平下，避免缺氧不能归因于自发游泳速度的变化，无论是在常氧还是在缺氧环境中。将 DO 水平降低到 60%空气饱和度会导致在常氧环境中自发游泳速度降低，但去测试区域缺氧侧的次数保持不变。此外，数据显示在 DO 水平≤60%空气饱和度时，每次去常氧的平均停留时间增加，而在 DO 水平≤50%空气饱和度时，每次去缺氧的平均停留时间减少。最后，在 DO 水平≤40%空气饱和度时，缺氧环境中的自发游泳速度增加，而在 30% DO 空气饱和度时，去缺氧的次数减少。因此，避免最深的缺氧与去缺氧的次数减少以及常氧和缺氧时自发游泳速度的减少和增加有关。总的来说，这些数据支持这样的结论，即避免缺氧的机制基础可能（1）不涉及轻度缺氧期间游泳速度的变化，和（2）取决于缺氧的严重程度。
