Department of Biology, University of Victoria, PO Box 1700 Station CSC, Victoria, BC, V8W 2Y2, Canada.
School of Aquatic and Fishery Sciences, University of Washington, 1122 NE Boat St, Seattle, WA, 98105, USA.
Nat Commun. 2020 Dec 8;11(1):6097. doi: 10.1038/s41467-020-19169-y.
Prospects for coral persistence through increasingly frequent and extended heatwaves seem bleak. Coral recovery from bleaching is only known to occur after temperatures return to normal, and mitigation of local stressors does not appear to augment coral survival. Capitalizing on a natural experiment in the equatorial Pacific, we track individual coral colonies at sites spanning a gradient of local anthropogenic disturbance through a tropical heatwave of unprecedented duration. Unexpectedly, some corals survived the event by recovering from bleaching while still at elevated temperatures. These corals initially had heat-sensitive algal symbiont communities, endured bleaching, and then recovered through proliferation of heat-tolerant symbionts. This pathway to survival only occurred in the absence of strong local stressors. In contrast, corals in highly disturbed areas were already dominated by heat-tolerant symbionts, and despite initially resisting bleaching, these corals had no survival advantage in one species and 3.3 times lower survival in the other. These unanticipated connections between disturbance, coral symbioses and heat stress resilience reveal multiple pathways to coral survival through future prolonged heatwaves.
珊瑚在越来越频繁和长时间的热浪中得以幸存的前景似乎黯淡。人们只知道珊瑚在水温恢复正常后才能从白化中恢复，而减轻局部压力似乎并不能提高珊瑚的存活率。利用赤道太平洋的一个自然实验，我们在跨越热带热浪的不同地点追踪个体珊瑚群体，这些地点的局部人为干扰程度不同。出乎意料的是，一些珊瑚在高温下从白化中恢复过来，从而在这次事件中幸存下来。这些珊瑚最初具有对热敏感的藻类共生体群落，经历了白化，然后通过耐热共生体的增殖而恢复。这种生存途径仅在没有强烈局部压力的情况下发生。相比之下，在受干扰严重的地区，珊瑚已经被耐热共生体所主导，尽管最初能够抵抗白化，但这些珊瑚在一个物种中没有生存优势，而在另一个物种中则降低了 3.3 倍的存活率。这些关于干扰、珊瑚共生体和耐热压力恢复能力之间意想不到的联系，揭示了珊瑚在未来长时间热浪中生存的多种途径。
