Coral Reef Research Unit, School of Biological Sciences, University of Essex, Essex, UK.
Marine Biology Department, Faculty of Science, Al-Azhar University, Nasr City, Cairo, Egypt.
Glob Chang Biol. 2018 Feb;24(2):e474-e484. doi: 10.1111/gcb.13895. Epub 2017 Oct 17.
Tropical reefs have been impacted by thermal anomalies caused by global warming that induced coral bleaching and mortality events globally. However, there have only been very few recordings of bleaching within the Red Sea despite covering a latitudinal range of 15° and consequently it has been considered a region that is less sensitive to thermal anomalies. We therefore examined historical patterns of sea surface temperature (SST) and associated anomalies (1982-2012) and compared warming trends with a unique compilation of corresponding coral bleaching records from throughout the region. These data indicated that the northern Red Sea has not experienced mass bleaching despite intensive Degree Heating Weeks (DHW) of >15°C-weeks. Severe bleaching was restricted to the central and southern Red Sea where DHWs have been more frequent, but far less intense (DHWs <4°C-weeks). A similar pattern was observed during the 2015-2016 El Niño event during which time corals in the northern Red Sea did not bleach despite high thermal stress (i.e. DHWs >8°C-weeks), and bleaching was restricted to the central and southern Red Sea despite the lower thermal stress (DHWs < 8°C-weeks). Heat stress assays carried out in the northern (Hurghada) and central (Thuwal) Red Sea on four key reef-building species confirmed different regional thermal susceptibility, and that central Red Sea corals are more sensitive to thermal anomalies as compared to those from the north. Together, our data demonstrate that corals in the northern Red Sea have a much higher heat tolerance than their prevailing temperature regime would suggest. In contrast, corals from the central Red Sea are close to their thermal limits, which closely match the maximum annual water temperatures. The northern Red Sea harbours reef-building corals that live well below their bleaching thresholds and thus we propose that the region represents a thermal refuge of global importance.
热带珊瑚礁受到全球变暖引起的热异常的影响，导致全球范围内珊瑚白化和死亡事件。然而，红海虽然覆盖了 15°的纬度范围，但仅有极少数的白化记录，因此被认为是对热异常不太敏感的区域。我们因此检查了历史上海域表面温度（SST）和相关异常（1982-2012 年）的模式，并将变暖趋势与整个地区独特的珊瑚白化记录进行了比较。这些数据表明，尽管经历了密集的超过 15°C 周数的强烈加热周（DHW），但红海北部并未经历大规模白化现象。严重白化现象仅限于红海中部和南部，那里的 DHW 更为频繁，但强度要低得多（DHW <4°C 周数）。在 2015-2016 年厄尔尼诺事件期间也观察到了类似的模式，当时尽管红海北部的热应力很高（即 DHW >8°C 周数），但珊瑚并未白化，白化现象仅限于红海中部和南部，尽管热应力较低（DHW <8°C 周数）。在红海北部（胡尔格达）和中部（图瓦尔）进行的四项关键造礁物种的热应激试验证实了不同区域的热敏感性，并且红海中部的珊瑚对热异常的敏感性高于北部。总的来说，我们的数据表明，红海北部的珊瑚具有比其现有温度范围更高的耐热性。相比之下，红海中部的珊瑚接近其热极限，这与最高年平均水温非常接近。红海北部拥有生活在远低于其白化阈值的造礁珊瑚，因此我们认为该地区是一个具有全球重要性的热避难所。
