PDF(Pubmed)
Abstract：
Coral reefs face an uncertain future punctuated by recurring climate-induced disturbances. Understanding how reefs can recover from and reassemble after mass bleaching events is therefore important to predict their responses and persistence in a rapidly changing ocean. On naturally extreme reefs characterized by strong daily temperature variability, coral heat tolerance can vary significantly over small spatial gradients but it remains poorly understood how this impacts bleaching resilience and recovery dynamics, despite their importance as resilience hotspots and potential refugia. In the macrotidal Kimberley region in NW Australia, the 2016 global mass bleaching event had a strong habitat-specific impact on intertidal and subtidal coral communities at our study site: corals in the thermally variable intertidal bleached less severely and recovered within six months, while 68% of corals in the moderately variable subtidal died. We therefore conducted benthic surveys 3.5 years after the bleaching event to determine potential changes in benthic cover and coral community composition. In the subtidal, we documented substantial increases in algal cover and live coral cover had not fully recovered to pre-bleaching levels. Furthermore, the subtidal coral community shifted from being dominated by branching Acropora corals with a competitive life history strategy to opportunistic, weedy Pocillopora corals which likely has implications for the functioning and stress resilience of this novel coral community. In contrast, no shifts in algal and live coral cover or coral community composition occurred in the intertidal. These findings demonstrate that differences in coral heat tolerance across small spatial scales can have large consequences for bleaching resilience and that spatial patchiness in recovery trajectories and community reassembly after bleaching might be a common feature on thermally variable reefs. Our findings further confirm that reefs adapted to high daily temperature variability play a key role as resilience hotspots under current climate conditions, but their ability to do so may be limited under intensifying ocean warming.
摘要：
珊瑚礁面临着不确定的未来，气候引起的干扰不断出现。因此，了解珊瑚礁如何在大规模漂白事件后恢复和重组，对于预测它们在快速变化的海洋中的反应和持久性非常重要。在以强烈的每日温度变化为特征的自然极端珊瑚礁上，珊瑚的耐热性可以在小的空间梯度显著变化，但它仍然知之甚少，这如何影响漂白弹性和恢复动态，尽管它们作为复原力热点和潜在避难所的重要性。在澳大利亚西北部的大潮金伯利地区，2016年全球大规模漂白事件对我们研究地点的潮间带和潮下珊瑚群落产生了强烈的栖息地特定影响:潮间带热变珊瑚漂白程度较低，并在六个月内恢复，而中度变潮下的珊瑚中有68％死亡。因此，我们在漂白事件发生3.5年后进行了底栖调查，以确定底栖覆盖和珊瑚群落组成的潜在变化。在潮下，我们记录了藻类覆盖率的大幅增加，活珊瑚覆盖率尚未完全恢复到漂白前的水平。此外，潮下珊瑚群落从具有竞争性生活史策略的分支Acropora珊瑚为主转变为机会主义，杂草的Pocillopora珊瑚可能对这种新型珊瑚群落的功能和抗逆性产生影响。相比之下,潮间带的藻类和活珊瑚覆盖或珊瑚群落组成没有变化。这些发现表明，在小空间尺度上珊瑚耐热性的差异可能会对漂白恢复能力产生重大影响，并且漂白后恢复轨迹和群落重组的空间斑块可能是热变珊瑚礁的共同特征。我们的研究结果进一步证实，适应每日高温变化的珊瑚礁在当前气候条件下作为恢复力热点发挥着关键作用。但是在海洋变暖加剧的情况下，他们这样做的能力可能会受到限制。
