Canadian Journal of Fisheries and Aquatic Sciences, Ahead of Print.
For freshwater fishes, elevated water temperatures associated with climate warming and hypoxia can co-occur and are likely to interact as both affect oxidative metabolism. We quantified the effects of acclimation to elevated temperature and hypoxia on the thermal tolerance of pugnose shiner (Notropis anogenus), a cyprinid fish threatened in its Canadian range. In one experiment, pugnose shiner underwent two-week sequential acclimations to six increasing temperatures. Fish acclimated to warmer waters increased their critical thermal maximum (CTmax), while the agitation temperature (Tag) was 3.4 °C lower than the CTmax. In another experiment, fish were acclimated to three dissolved oxygen treatments (>95%, ∼56%, or ∼40% air saturation) for two weeks and tested under >95% and 40% conditions. CTmax was lower when measured under 40% for normoxia-acclimated fish but not for hypoxia-acclimated fish. Hypoxia-acclimated fish had higher Tag and smaller agitation windows than normoxia-acclimated fish, suggesting that hypoxia acclimation improves aspects of thermal tolerance. We examine the plasticity of thermal tolerance of pugnose shiner, showing that they may be more vulnerable to high temperatures compared with other non-imperiled Notropis species.

中文翻译：

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适应升高的水温和缺氧对受威胁的美洲虎（Notropis anogenus）热耐受性的影响

加拿大渔业和水产科学杂志，提前印刷。
对于淡水鱼，与气候变暖和缺氧相关的水温升高可以同时发生，并且可能相互作用，因为两者都会影响氧化代谢。我们量化了适应升高的温度和缺氧对 pugnose silverer (Notropis anogenus) 热耐受性的影响，这是一种在其加拿大范围内受到威胁的鲤科鱼类。在一项实验中，pugnose Shiner 经历了为期两周的连续适应六次升高的温度。适应温暖水域的鱼增加了它们的临界热最大值 (CTmax)，而搅拌温度 (Tag) 比 CTmax 低 3.4 °C。在另一个实验中，鱼适应三种溶解氧处理（>95%、~56% 或~40% 空气饱和度）两周，并在 >95% 和 40% 的条件下进行测试。当测量低于 40% 时，常氧适应鱼的 CTmax 较低，而缺氧适应鱼则不然。与常氧驯化的鱼相比，缺氧驯化的鱼具有更高的 Tag 和更小的搅拌窗口，这表明缺氧驯化提高了热耐受性。我们检查了美洲虎的耐热性的可塑性，表明与其他未受危害的 Notropis 物种相比，它们可能更容易受到高温的影响。