Beyond peak summer temperatures, branching corals in the Gulf of Aqaba are resilient to thermal stress but sensitive to high light
Beyond peak summer temperatures, branching corals in the Gulf of Aqaba are resilient to thermal stress but sensitive to high light
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DOI：
10.1007/s00338-017-1598-1
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发表时间：
2017-12-01
期刊：
影响因子：
3.5
通讯作者：
Fine, Maoz
中科院分区：
文献类型：
--
作者：
Bellworthy, Jessica;Fine, Maoz
尽管海面温度迅速上升，经常出现正温度异常，但亚喀巴湾（果阿）的珊瑚很少经历热漂白。在其他地方，当水温比当地最高月平均温度高出1-2摄氏度时，珊瑚就会出现大规模的珊瑚白化现象。这一阈值或“白化规则”已被用于根据卫星海洋表面温度观测建立白化预测模型，即“周升温度”指数。本研究旨在描述果阿主要造礁珊瑚在温度和光照应力梯度下的生理变化。在MMM以上连续14天的野外采集和实验开始。Stylophora pistillata共生体和宿主生理参数的变化可以忽略不计，积累了9.4度加热周在夏季温度高峰期，该指数预测广泛的漂白和一些死亡率。这一结果表明，急性热耐受性在S。pistillata从果阿和偏离漂白规则。在第二个实验中，在比夏季最高温度高出4摄氏度的环境中呆了4周后，S。pistillata和Acroporaeurystoma在高光处理明显苍白，并遭受更大的中午和下午的光抑制相比，珊瑚在低光条件下（35%的高光处理）。然而，光，而不是温度（单独或与光协同），是导致苍白的主导因素，珊瑚在高于环境温度4 A摄氏度的有效量子产率与环境控制中的珊瑚没有区别。这一结果突出了占主导地位的果阿分支珊瑚的特殊，非典型的耐热性。与此同时，如果要使果阿的珊瑚礁在全球海水温度上升的情况下成为珊瑚礁的避难所，这也证明了保护这些珊瑚礁不受当地压力的影响是有效的。
Despite rapidly rising sea surface temperatures and recurrent positive temperature anomalies, corals in the Gulf of Aqaba (GoA) rarely experience thermal bleaching. Elsewhere, mass coral bleaching has been observed in corals when the water temperature exceeds 1-2 A degrees C above the local maximum monthly mean (MMM). This threshold value or "bleaching rule" has been used to create predictive models of bleaching from satellite sea surface temperature observations, namely the "degree heating week" index. This study aimed to characterize the physiological changes of dominant reef building corals from the GoA in response to a temperature and light stress gradient. Coral collection and experiments began after a period of 14 consecutive days above MMM in the field. Stylophora pistillata showed negligible changes in symbiont and host physiology parameters after accumulating up to 9.4 degree heating weeks during peak summer temperatures, for which the index predicts widespread bleaching and some mortality. This result demonstrates acute thermal tolerance in S. pistillata from the GoA and deviation from the bleaching rule. In a second experiment after 4 weeks at 4 A degrees C above peak summer temperatures, S. pistillata and Acropora eurystoma in the high-light treatment visibly paled and suffered greater midday and afternoon photoinhibition compared to corals under low-light conditions (35% of high-light treatment). However, light, not temperature (alone or in synergy with light), was the dominant factor in causing paling and the effective quantum yield of corals at 4 A degrees C above ambient was indistinguishable from those in the ambient control. This result highlights the exceptional, atypical thermal tolerance of dominant GoA branching corals. Concomitantly, it validates the efficacy of protecting GoA reefs from local stressors if they are to serve as a coral refuge in the face of global sea temperature rise.