Warm‐season marine heatwaves (MHWs) have greatly increased in frequency, severity, and extent over the last few decades, driving more frequent and severe coral bleaching episodes. Given the grave near‐term threat to coral reefs imposed by MHWs, it is important to assess the mechanisms by which corals may acquire higher thermal tolerance. Recent field and laboratory studies have demonstrated that exposure to sublethal heat stress, known as “priming,” can reduce bleaching susceptibility during a subsequent MHW. Little is known, however, about how often priming conditions occur, and how effective those conditions may be at protecting coral reefs. We employed a global historical coral bleaching database and a high‐resolution sea surface temperature dataset to assess the frequency of priming and examine its effect on coral bleaching sensitivity on a global scale. The analysis showed that coral reefs in parts of the western to central tropical Pacific experienced priming on average over twice a decade and had a higher likelihood of priming protection. Mixed‐effects regression models indicated that priming conditions could mitigate coral bleaching response by up to 12% in advance of a moderate MHW. However, the protective effect of priming decreased, and even became harmful, with more severe MHWs. We detected spatial variations in priming frequency that could provide insight for conservation planning and explain some variations in bleaching sensitivity to MHWs. Even so, our findings suggest that thermal priming will not be sufficient to protect most coral reefs from MHWs in the future, without substantial efforts to mitigate climate change.

中文翻译：

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全球珊瑚礁上有益的热启动物的丧失


在过去的几十年里，暖季海洋热浪 （MHW） 的频率、严重程度和范围大大增加，导致珊瑚白化事件更加频繁和严重。鉴于 MHW 对珊瑚礁构成的近期严重威胁，评估珊瑚获得更高耐热性的机制非常重要。最近的现场和实验室研究表明，暴露于亚致死性热应激（称为“引发”）可以降低后续 MHW 期间的白化敏感性。然而，关于引发条件发生的频率以及这些条件在保护珊瑚礁方面的有效性，我们知之甚少。我们利用全球历史珊瑚白化数据库和高分辨率海面温度数据集来评估启动频率并检查其对全球珊瑚白化敏感性的影响。分析表明，热带太平洋西部至中部部分地区的珊瑚礁平均每十年经历两次引发，并且受到引发保护的可能性更高。混合效应回归模型表明，在中度 MHW 之前，启动条件可以将珊瑚白化反应减轻高达 12%。然而，启动的保护作用降低，甚至变得有害，MHW 更严重。我们检测到了引发频率的空间变化，这可以为保护计划提供见解，并解释对 MHW 的漂白敏感性的一些变化。即便如此，我们的研究结果表明，如果不做出实质性努力来缓解气候变化，热启动将不足以保护未来大多数珊瑚礁免受 MHW 的侵害。