Anticipating future changes of an ecosystem's dynamics requires knowledge of how its key communities respond to current environmental regimes. The Great Barrier Reef (GBR) is under threat, with rapid changes of its reef-building hard coral community structure already evident across broad spatial scales. While many of the underlying relationships between hard corals and multiple disturbances have been documented, responses of other benthic communities to disturbances are not well understood. Here, we used statistical modelling to explore the effects of broad-scale climate-related disturbances on benthic communities to predict their structure under scenarios of increasing disturbance frequency. We parameterized a multivariate model using the composition of benthic communities estimated by 145,000 observations from the northern GBR between 2012 and 2017. During this time, surveyed reefs were variously impacted by two tropical cyclones and two heat stress events that resulted in extensive hard coral mortality. This unprecedented sequence of disturbances was used to estimate the effects of discrete versus interacting disturbances on the compositional structure of hard corals, soft corals, and algae. Discrete disturbances increased the prevalence of algae relative to hard corals while the interaction between cyclones and heat stress was the main driver of the increase in soft corals relative to algae and hard corals. Predictions from disturbance scenarios included relative increases in algae versus soft corals that varied by the frequency and types of disturbance interactions. However, high un-certainty of compositional changes in the presence of several disturbances shows that responses of algae and soft corals to the decline in hard corals needs further research. Better understanding the effects of multiple disturbances on benthic communities as a whole is essential for predicting the future status of coral reefs and managing them in the light of new environmental regimes. The approach we develop here opens new opportunities for reaching this goal.

中文翻译：

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预测对珊瑚礁的干扰作用正在加剧。

预测生态系统动力学的未来变化，需要了解其关键社区如何响应当前环境状况。大堡礁（GBR）受到威胁，其珊瑚礁建设硬珊瑚群落结构的迅速变化在广泛的空间尺度上已经显而易见。虽然已记录了硬珊瑚与多重干扰之间的许多潜在关系，但其他底栖生物群落对干扰的反应仍未充分了解。在这里，我们使用统计模型来探讨大规模气候相关干扰对底栖生物的影响，以预测在干扰频率增加的情况下底栖生物的结构。我们使用145个估计的底栖动物群落组成参数化了一个多元模型，2012年至2017年间，GBR北部地区进行了000次观测。在此期间，两次热带气旋和两次热应激事件对受调查的礁石造成了不同程度的影响，导致广泛的硬珊瑚死亡。这种前所未有的干扰序列被用来估计离散干扰与相互作用干扰对硬珊瑚，软珊瑚和藻类组成结构的影响。离散的干扰增加了藻类相对于硬珊瑚的流行，而旋风分离器和热应力之间的相互作用是软珊瑚相对于藻类和硬珊瑚增加的主要驱动力。对干扰情景的预测包括藻类与软珊瑚的相对增加，其随干扰相互作用的频率和类型而变化。然而，在存在多种干扰的情况下，成分变化的不确定性很高，这表明藻类和软珊瑚对硬珊瑚下降的反应需要进一步研究。更好地了解多种干扰对整个底栖生物的影响，对于预测珊瑚礁的未来状况并根据新的环境制度进行管理至关重要。我们在这里开发的方法为实现该目标提供了新的机会。