Coral reefs are in global decline and anomalously hot temperatures shoulder the blame. Foraminferal bioindicators are important because they record historical reef stress over periods of centuries to millennia, as compared to the few decades offered by diver surveys. For a region lacking systematic long-term reef monitoring programs, the use of bioindicators in the Red Sea is compelling. Whereas foraminfera-based indices exist to reconstruct histories of nutrient stress on reefs, there is a paucity of equivalent bioindicators that respond to temperature. Capitalizing on a portfolio of surficial sediment samples collected along the eastern margin of the N. Red Sea and Gulf of Aqaba, this study shows that the relative abundance of Amphisteginidae foraminifera—specifically Amphistegina lobifera—closely track heat stress, as has recently been reported for this family in the S. Pacific. This result is consequential for at least three reasons. First, the Red Sea hosts some of the most northerly coral reefs on Earth. Establishment of a thermal bioindicator here confirms the strategy can be deployed on high latitudes reefs, which are disproportionally afflicted with heat extremes. Second, the considered reefs, and the foraminifera they host, are famed for their thermal resilience. Foraminiferal bioindicators have not previously been trialed on reefs that have adapted in this way. Finally, as a restricted offshoot of the Indian Ocean, the level of endemism in the Red Sea is especially high. The bioindicator that we propose is apparently not compromised by endemism. Our findings advocate for an expanded deployment of Amphistegina-based reef bioindicators.

珊瑚礁在全球范围内衰退，异常高温是罪魁祸首。有孔虫生物指标很重要，因为与潜水员调查提供的几十年相比，它们记录了数百年至数千年的历史珊瑚礁压力。对于一个缺乏系统的长期珊瑚礁监测计划的地区来说，在红海使用生物指示剂是引人注目的。尽管存在基于有孔虫的指数来重建珊瑚礁营养压力的历史，但对温度作出反应的等效生物指标却很少。利用沿北红海和亚喀巴湾东缘收集的一系列地表沉积物样本，本研究表明，有孔虫科（特别是Amphistegina lobifera ）的相对丰度密切跟踪热应激，正如最近在南太平洋的这个家庭所报道的那样。这个结果是必然的，至少有三个原因。首先，红海拥有地球上一些最北端的珊瑚礁。在这里建立一个热生物指示物证实了该策略可以部署在高纬度珊瑚礁上，这些珊瑚礁不成比例地受到极端高温的影响。其次，所考虑的珊瑚礁以及它们所栖息的有孔虫，以其热弹性而闻名。以前没有在以这种方式适应的珊瑚礁上试验过有孔虫生物指示物。最后，作为印度洋的一个受限制的分支，红海的特有水平特别高。我们提出的生物指标显然没有受到地方性的影响。我们的研究结果主张扩大部署基于Amphistegina的珊瑚礁生物指标。