Highly variable thermal environments, such as coral reef flats, are challenging for marine ectotherms, and are thought to invoke the use of behavioural strategies to avoid extreme temperatures and seek out thermal environments close to their preferred temperatures. Common to coral reef flats, the epaulette shark (Hemiscyllium ocellatum) possesses physiological adaptations to hypoxic and hypercapnic conditions, such as those experienced on reef flats; however, little is known regarding the thermal strategies used by these sharks. We investigated whether H. ocellatum uses behavioural thermoregulation (i.e., movement to occupy thermally favourable microhabitats) or tolerates the broad range of temperatures experienced on the reef flat. Using an automated shuttlebox system, we determined the preferred temperature of H. ocellatum under controlled laboratory conditions and then compared this preferred temperature to 6-months of in situ environmental and body temperatures of individual H. ocellatum across the Heron Island reef flat. The preferred temperatures of H. ocellatum under controlled conditions was 20.7±1.5°C, however body temperatures of individual H. ocellatum on the Heron Island reef flat mirrored that of environmental temperatures regardless of season or month. Despite substantial temporal variation in temperature on the Heron Island reef flat (15-34°C during 2017), there was a lack of spatial variation in temperature across the reef flat, between sites or microhabitats. This limited spatial variation in temperature creates a low-quality thermal habitat limiting the ability of H. ocellatum to behaviourally thermoregulate. Behavioural thermoregulation is assumed in many shark species, but it appears that H. ocellatum may utilize other physiological strategies to cope with extreme temperature fluctuations on coral reef flats. While H. ocellatum appears to be able to tolerate acute exposure to temperatures well outside of their preferred temperature, it is unclear how this, and other, species will cope as temperatures continue to rise and approach their critical thermal limits. Understanding how species will respond to continued warming and the strategies they may use will be key to predicting future populations and assemblages. This article is protected by copyright. All rights reserved.

中文翻译：

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调节或容忍：珊瑚礁平原居民的热策略，肩章鲨 Hemiscyllium ocellatum

高度可变的热环境，例如珊瑚礁滩，对海洋变温动物来说具有挑战性，并且被认为需要使用行为策略来避免极端温度并寻找接近其首选温度的热环境。肩章鲨（Hemiscyllium ocellatum）在珊瑚礁滩很常见，对缺氧和高碳酸血症条件具有生理适应性，例如在礁滩上遇到的情况；然而，人们对这些鲨鱼使用的热量策略知之甚少。我们调查了 H. ocellatum 是否使用行为体温调节（即，移动以占据对热有利的微生境）或容忍礁滩上经历的广泛温度范围。使用自动梭箱系统，我们确定了 H 的首选温度。ocellatum 在受控的实验室条件下进行，然后将该首选温度与整个 Heron Island 礁滩的单个 H. ocellatum 6 个月的原位环境温度和体温进行比较。H. ocellatum 在受控条件下的首选温度为 20.7±1.5°C，但无论季节或月份如何，Heron Island 礁滩上的单个 H. ocellatum 的体温都反映了环境温度。尽管苍鹭岛礁坪的温度在时间上有很大变化（2017 年为 15-34°C），但整个礁坪、地点或微生境之间的温度没有空间变化。这种有限的温度空间变化创造了一个低质量的热栖息地，限制了 H. ocellatum 行为体温调节的能力。许多鲨鱼物种都假设有行为体温调节，但似乎 H. ocellatum 可能利用其他生理策略来应对珊瑚礁平面上的极端温度波动。虽然 H. ocellatum 似乎能够耐受远超出其首选温度的剧烈温度，但尚不清楚随着温度继续升高并接近其临界热极限，这种和其他物种将如何应对。了解物种将如何应对持续变暖以及它们可能使用的策略将是预测未来种群和组合的关键。本文受版权保护。版权所有。ocellatum 似乎能够耐受远远超出其首选温度的急性温度，目前尚不清楚随着温度继续升高并接近其临界热极限，该物种和其他物种将如何应对。了解物种将如何应对持续变暖以及它们可能使用的策略将是预测未来种群和组合的关键。本文受版权保护。版权所有。ocellatum 似乎能够耐受远远超出其首选温度的急性温度，目前尚不清楚随着温度继续升高并接近其临界热极限，该物种和其他物种将如何应对。了解物种将如何应对持续变暖以及它们可能使用的策略将是预测未来种群和组合的关键。本文受版权保护。版权所有。了解物种将如何应对持续变暖以及它们可能使用的策略将是预测未来种群和组合的关键。本文受版权保护。版权所有。了解物种将如何应对持续变暖以及它们可能使用的策略将是预测未来种群和组合的关键。本文受版权保护。版权所有。