Nilsson Göran E, Ostlund-Nilsson Sara, Penfold Rose, Grutter Alexandra S
Physiology Programme, Department of Molecular Biosciences, University of Oslo, PO Box 1041, 0316 Oslo, Norway.
Proc Biol Sci. 2007 Jan 7;274(1606):79-85. doi: 10.1098/rspb.2006.3706.
The fastest swimming fishes in relation to size are found among coral reef fish larvae on their way to settle on reefs. By testing two damselfishes, Chromis atripectoralis and Pomacentrus amboinensis, we show that the high swimming speeds of the pre-settlement larvae are accompanied by the highest rates of oxygen uptake ever recorded in ectothermic vertebrates. As expected, these high rates of oxygen uptake occur at the cost of poor hypoxia tolerance. However, hypoxia tolerance is needed when coral reef fishes seek nocturnal shelter from predators within coral colonies, which can become severely hypoxic microhabitats at night. When the larvae settle on the reef, we found that they go through a striking respiratory transformation, i.e. the capacity for rapid oxygen uptake falls, while the ability for high-affinity oxygen uptake at low oxygen levels is increased. This transition to hypoxia tolerance is needed when they settle on the reef; this was strengthened by our finding that small resident larvae of Acanthochromis polyacanthus, a damselfish lacking a planktonic larval stage, do not display such a transition, being well adapted to hypoxia and showing relatively low maximum rates of oxygen uptake that change little with age.
就体型而言，游动速度最快的鱼类存在于正前往珊瑚礁定居的珊瑚礁鱼类幼体之中。通过对两种雀鲷——黑鳍光鳃雀鲷和安汶雀鲷进行测试，我们发现，定居前幼体的高游动速度伴随着变温脊椎动物中记录到的最高耗氧率。不出所料，这些高耗氧率是以低耐缺氧能力为代价的。然而，当珊瑚礁鱼类在夜间寻找躲避珊瑚群体中捕食者的庇护所时，就需要耐缺氧能力，因为这些珊瑚群体在夜间可能会变成严重缺氧的微生境。当幼体在珊瑚礁上定居时，我们发现它们会经历显著的呼吸转变，即快速摄取氧气的能力下降，而在低氧水平下高亲和力摄取氧气的能力增强。当它们在珊瑚礁上定居时，这种向耐缺氧能力的转变是必要的；我们的研究结果进一步证实了这一点，即多棘刺尻鱼（一种没有浮游幼体阶段的雀鲷）的小型定居幼体不会表现出这种转变，它们非常适应缺氧环境，并且显示出相对较低的最大耗氧率，且随着年龄增长变化不大。
