Booth David T
The University of Queensland, Physiological Ecology Group, School of Integrative Biology, Qld 4072, Australia.
J Exp Biol. 2009 Jan;212(Pt 1):50-5. doi: 10.1242/jeb.019778.
Swimming effort and oxygen consumption of newly emerged green turtle Chelonia mydas hatchlings was measured simultaneously and continuously for the first 18 h of swimming after hatchlings entered the water. Oxygen consumption was tightly correlated to swimming effort during the first 12 h of swimming indicating that swimming is powered predominantly by aerobic metabolism. The patterns of swimming effort and oxygen consumption could be divided into three distinct phases: (1) the rapid fatigue phase from 0 to 2 h when the mean swim thrust decreased from 45 to 30 mN and oxygen consumption decreased from 33 to 18 ml h(-1); (2) the slow fatigue phase from 2 to 12 h when the mean swim thrust decreased from 30 to 22 mN and oxygen consumption decreased from 18 to 10 ml h(-1); and (3) the sustained effort phase from 12 to 18 h when mean swim thrust averaged 22 mN and oxygen consumption averaged 10 ml h(-1). The decrease in mean swim thrust was caused by a combination of a decrease in front flipper stroke rate during a power stroking bout, a decrease in mean maximum thrust during a power stroking bout and a decrease in the proportion of time spent power stroking. Hence hatchlings maximise their swimming thrust as soon as they enter the water, a time when a fast swimming speed will maximise the chance of surviving the gauntlet of predators inhabiting the shallow fringing reef before reaching the relative safety of deeper water.
在新生绿海龟蠵龟幼体入水后的前18小时游泳过程中，同时持续测量了它们的游泳用力情况和耗氧量。在游泳的前12小时内，耗氧量与游泳用力情况紧密相关，这表明游泳主要由有氧代谢提供动力。游泳用力情况和耗氧量的模式可分为三个不同阶段：（1）快速疲劳阶段，从0至2小时，平均游泳推力从45毫牛降至30毫牛，耗氧量从33毫升/小时降至18毫升/小时；（2）缓慢疲劳阶段，从2至12小时，平均游泳推力从30毫牛降至22毫牛，耗氧量从18毫升/小时降至10毫升/小时；（3）持续用力阶段，从12至18小时，平均游泳推力平均为22毫牛，耗氧量平均为10毫升/小时。平均游泳推力的下降是由以下因素共同导致的：在动力划水回合中前鳍划水频率降低、动力划水回合中平均最大推力降低以及动力划水所用时间比例降低。因此，幼体一旦入水就会将游泳推力最大化，此时快速的游泳速度将最大程度提高其在抵达较深水域的相对安全区域之前，从栖息在浅海边缘礁的众多捕食者手中幸存的几率。
