Local habitat heterogeneity rivals regional differences in coral thermal tolerance
Local habitat heterogeneity rivals regional differences in coral thermal tolerance
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DOI：
10.1007/s00338-024-02484-x
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发表时间：
2024-04-03
期刊：
影响因子：
3.5
通讯作者：
Barott，Katie L.
中科院分区：
文献类型：
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作者：
Brown，Kristen T.;Martynek，Marcelina P.;Barott，Katie L.
使珊瑚暴露在亚致死热应激下的可变温度制度已被认为是增加珊瑚耐热性和减轻珊瑚白化的一种机制。然而，有必要更好地了解哪种热状态使珊瑚应力硬化最大化。本研究采用标准化热应力法测定了来自6个珊瑚礁遗址的3种不同属珊瑚（Acropora,Pocillopora,Porites）的相对耐热性，这些遗址的年平均日平均温度波动梯度为1 - 3°C。在23.0至36.3°C的5个温度处理下，对白化严重程度和暗驯化光化学产量（即Fv/Fm）进行了量化。在平均温度变化中等（2.2°C day - 1）的部位发现了最大的热耐受性（即Fv/ f有效剂量50），表明存在导致最大热耐受性的最佳起始暴露。有趣的是，来自最小热变化区（< 1.3°C day - 1）的acropora&pocillopora&acropora&pocillopora&acropora&pocillopora&acropora&pocillopora&acropora&pocillopora&acropora&pocillopora&acropora&pocillopora&acropora&pocpoa&poc)的耐热性低于来自最热变化区（< 2.8°C day - 1）的珊瑚，而porites则相反，这表明不同分类群的响应存在差异。值得注意的是，与全球研究的比较表明，本研究中发现的珊瑚在单个珊瑚礁（< 5公里）上的热耐受性范围与在巨大的纬度梯度（300-900公里）上观察到的差异一样大。这一发现表明，局部基因流动可以提高不同生境间的热耐受性。然而，随着气候变化的持续，暴露在日益加剧的海洋热浪中，已经损害了热启动作为增强珊瑚耐热性和抗白化性的机制。
Variable temperature regimes that expose corals to sublethal heat stress have been recognized as a mechanism to increase coral thermal tolerance and lessen coral bleaching. However, there is a need to better understand which thermal regimes maximize coral stress hardening. Here, standardized thermal stress assays were used to determine the relative thermal tolerance of three divergent genera of corals (Acropora,Pocillopora,Porites) originating from six reef sites representing an increasing gradient of annual mean diel temperature fluctuations of 1–3 °C day−1. Bleaching severity and dark-acclimated photochemical yield (i.e.,Fv/Fm) were quantified following exposure to five temperature treatments ranging from 23.0 to 36.3 °C. The greatest thermal tolerance (i.e.,Fv/Fmeffective dose 50) was found at the site with intermediate mean diel temperature variability (2.2 °C day−1), suggesting there is an optimal priming exposure that leads to maximal thermal tolerance. Interestingly,AcroporaandPocilloporaoriginating from the least thermally variable regimes (< 1.3 °C day−1) had lower thermal tolerance than corals from the most variable sites (> 2.8 °C day−1), whereas the opposite was true forPorites, suggesting divergent responses across taxa. Remarkably, comparisons across global studies revealed that the range in coral thermal tolerance uncovered in this study across a single reef (< 5 km) were as large as differences observed across vast latitudinal gradients (300–900 km). This finding indicates that local gene flow could improve thermal tolerance between habitats. However, as climate change continues, exposure to intensifying marine heatwaves is already compromising thermal priming as a mechanism to enhance coral thermal tolerance and bleaching resistance.