Mass coral bleaching has increased in intensity and frequency and has severely impacted shallow tropical reefs worldwide. Although extensive investigation has been conducted on the resistance and resilience of coral reefs in the Indo-Pacific and Caribbean, the unique reefs of the South Atlantic remain largely unassessed. Here we compiled primary and literature data for reefs from three biogeographical regions: Indo-Pacific, Caribbean and South Atlantic and performed comparative analyses to investigate whether the latter may be more resistant to bleaching. Our findings show that South Atlantic corals display critical features that make them less susceptible to mass coral bleaching: (i) deeper bathymetric distribution, as species have a mean maximum depth of occurrence of 70 m; (ii) higher tolerance to turbidity, as nearly 60% of species are found in turbid conditions; (iii) higher tolerance to nutrient enrichment, as nitrate concentration in the South Atlantic is naturally elevated; (iv) higher morphological resistance, as massive growth forms are dominant and comprise two thirds of species; and (v) more flexible symbiotic associations, as 75% of corals and 60% of symbiont phylotypes are generalists. Such features were associated with occurrence of fewer bleaching episodes with coral mortality in the South Atlantic, approximately 60% less than the Indo-Pacific and 50% less than the Caribbean. In addition, no mass coral mortality episodes associated with the three global mass bleaching events have been reported for the South Atlantic, which suffered considerably less bleaching. These results show that South Atlantic reefs display several remarkable features for withstanding thermal stress. Together with a historic experience of lower heat stress, our findings may explain why climate change impacts in this region have been less intense. Given the large extension and latitudinal distribution of South Atlantic coral reefs and communities, the region may be recognized as a major refugium and likely to resist climate change impacts more effectively than Indo-Pacific and Caribbean reefs.

中文翻译：

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南大西洋珊瑚礁是全球变暖的主要避难所，不易褪色

大规模珊瑚白化的强度和频率都在增加，并严重影响了全世界的浅层热带珊瑚礁。尽管对印度-太平洋和加勒比地区珊瑚礁的抵抗力和恢复力进行了广泛的调查，但南大西洋独特的珊瑚礁在很大程度上仍未得到评估。在这里，我们汇编了来自三个生物地理区域的珊瑚礁的原始和文献数据：印度洋-太平洋、加勒比海和南大西洋，并进行了比较分析，以调查后者是否更能抵抗白化。我们的研究结果表明，南大西洋珊瑚显示出关键特征，使它们不易受到大规模珊瑚白化的影响：(i) 更深的水深分布，因为物种的平均最大发生深度为 70 m；(ii) 更高的浊度耐受性，因为近 60% 的物种是在混浊环境中发现的；(iii) 对营养丰富的耐受性更高，因为南大西洋的硝酸盐浓度自然升高；(iv) 更高的形态抗性，因为大量生长形式占主导地位，占物种的三分之二；(v) 更灵活的共生关联，因为 75% 的珊瑚和 60% 的共生系统发育型是通才。这些特征与南大西洋珊瑚死亡率减少的白化事件的发生有关，比印度-太平洋少约 60%，比加勒比少约 50%。此外，南大西洋没有报告与三场全球大规模白化事件相关的大规模珊瑚死亡事件，南大西洋的白化程度要低得多。这些结果表明，南大西洋珊瑚礁在承受热应力方面表现出几个显着的特征。再加上热应激较低的历史经验，我们的研究结果可以解释为什么该地区的气候变化影响不那么强烈。鉴于南大西洋珊瑚礁和群落的大面积延伸和纬度分布，该地区可能被认为是一个主要的避难所，并且可能比印度-太平洋和加勒比珊瑚礁更有效地抵御气候变化的影响。