Chabot D, Claireaux G
Direction des sciences halieutiques et aquaculture, Ministère des Pêches et des Océans, Institut Maurice-Lamontagne, C.P. 1000, Mont-Joli, QC, Canada G5H 3Z4.
Mar Pollut Bull. 2008;57(6-12):287-94. doi: 10.1016/j.marpolbul.2008.04.001. Epub 2008 May 27.
Hypoxia is known to provoke a wide range of effects on aquatic animals. Here we use laboratory and field data on Atlantic cod, Gadus morhua, to illustrate that many of these responses can be explained within the metabolic scope (MS) framework, i.e. taking into account the directive and limiting effects of dissolved oxygen (DO) on the ability of animals to acquire energy for growth and activity. A MS model for cod shows that scope for activity (swimming, feeding, etc.) is proportional to DO and becomes nil, jeopardising survival, when DO is < approximately 20% air saturation. Laboratory studies have confirmed this lethal threshold and demonstrated that growth and food ingestion were significantly reduced below 70% sat. This loss of appetite has been linked to a reduction of the peak value and an increase in duration of postprandial metabolism, in agreement with the MS model. Dwindling MS during hypoxia imposes an upper limit to swimming performance. Cod may also opt to reduce spontaneous swimming activity to spare oxygen for other activities such as digestion. In the Kattegat, the Baltic Sea, and the Gulf of St. Lawrence, eastern Canada, cod completely avoid waters where their MS is near zero. Furthermore, cod density increases exponentially with DO up to approximately 70% sat in the Gulf of St. Lawrence. Although hypoxia results in other direct and indirect effects as well, the MS framework allows modelling of many of the responses to hypoxia for individual cod that ought to be reflected at the population and community levels. The MS framework is also useful to compare species responses. We show that the impact of hypoxia on MS is similar, when expressed as a proportion of MS in normoxia, in cod, European sea bass (Dicentrarchus labrax), the common sole (Solea solea) and turbot (Psetta maxima). Data are required for other species to evaluate how general these findings are.
众所周知，缺氧会对水生动物产生广泛影响。在此，我们利用关于大西洋鳕鱼（Gadus morhua）的实验室和野外数据，来说明这些反应中的许多都可以在代谢范围（MS）框架内得到解释，即考虑到溶解氧（DO）对动物获取生长和活动所需能量能力的指导和限制作用。鳕鱼的MS模型表明，活动范围（游泳、进食等）与DO成正比，当DO低于约20%空气饱和度时，活动范围变为零，危及生存。实验室研究已证实这一致死阈值，并表明当饱和度低于70%时，生长和食物摄取会显著减少。这种食欲下降与餐后代谢峰值降低和持续时间增加有关，这与MS模型一致。缺氧期间MS的减少对游泳性能设定了上限。鳕鱼也可能选择减少自发游泳活动，以便为消化等其他活动节省氧气。在卡特加特海峡、波罗的海以及加拿大东部的圣劳伦斯湾，鳕鱼完全避开其MS接近零的水域。此外，在圣劳伦斯湾，鳕鱼密度随DO呈指数增加，直至约70%饱和度。尽管缺氧还会导致其他直接和间接影响，但MS框架允许对个体鳕鱼对缺氧的许多反应进行建模，而这些反应应该在种群和群落水平上得到体现。MS框架对于比较物种反应也很有用。我们表明，当以常氧下MS的比例表示时，缺氧对MS的影响在鳕鱼、欧洲海鲈（Dicentrarchus labrax）、欧洲鳎（Solea solea）和大菱鲆（Psetta maxima）中是相似的。需要其他物种的数据来评估这些发现的普遍性如何。
