PDF(Pubmed)
Abstract：
Climate change is transforming coral reefs by increasing the frequency and intensity of marine heatwaves, often leading to coral bleaching and mortality. Coral communities have demonstrated modest increases in thermal tolerance following repeated exposure to moderate heat stress, but it is unclear whether these shifts represent acclimatization of individual colonies or mortality of thermally susceptible individuals. For corals that survive repeated bleaching events, it is important to understand how past bleaching responses impact future growth potential. Here, we track the bleaching responses of 1,832 corals in leeward Maui through multiple marine heatwaves and document patterns of coral growth and survivorship over a seven-year period. While we find limited evidence of acclimatization at population scales, we document reduced bleaching over time in specific individuals that is indicative of acclimatization, primarily in the stress-tolerant taxa Porites lobata. For corals that survived both bleaching events, we find no relationship between bleaching response and coral growth in three of four taxa studied. This decoupling suggests that coral survivorship is a better indicator of future growth than is a coral\'s bleaching history. Based on these results, we recommend restoration practitioners in Hawai\'i focus on colonies of Porites and Montipora with a proven track-record of growth and survivorship, rather than devote resources toward identifying and cultivating bleaching-resistant phenotypes in the lab. Survivorship followed a latitudinal thermal stress gradient, but because this gradient was small, it is likely that local environmental factors also drove differences in coral performance between sites. Efforts to reduce human impacts at low performing sites would likely improve coral survivorship in the future.
摘要：
气候变化通过增加海洋热浪的频率和强度来改变珊瑚礁，经常导致珊瑚白化和死亡。珊瑚群落在反复暴露于中度热应激后，表现出耐热性的适度增加，但尚不清楚这些变化是否代表单个菌落的适应或热敏感个体的死亡。对于在反复漂白事件中幸存下来的珊瑚，重要的是要了解过去的漂白反应如何影响未来的增长潜力。这里,我们通过多次海洋热浪跟踪了背风毛伊岛1,832颗珊瑚的漂白反应，并记录了七年来珊瑚生长和生存的模式。虽然我们发现在人口规模上适应的证据有限，我们记录了随着时间的推移，特定个体的漂白减少，这表明适应环境，主要在胁迫耐受类群中。对于在两次漂白事件中幸存下来的珊瑚来说，在研究的四个分类群中，我们发现漂白反应与珊瑚生长之间没有关系。这种脱钩表明，与珊瑚的漂白历史相比，珊瑚的存活率是未来生长的更好指标。基于这些结果,我们建议夏威夷的修复从业者专注于Porites和Montipora的殖民地，这些殖民地具有成熟的生长和生存记录，而不是投入资源在实验室中鉴定和培养抗漂白表型。幸存者遵循纬度热应力梯度，但是因为这个梯度很小，当地的环境因素也可能导致地点之间珊瑚表现的差异。在低表现的地点减少人类影响的努力可能会在未来提高珊瑚的存活率。
