ARC Centre of Excellence for Coral Reef Studies, School of Biological Sciences, The University of Queensland, St Lucia, Qld, Australia.
The Global Change Institute, The University of Queensland, St Lucia, Qld, Australia.
Glob Chang Biol. 2020 May;26(5):2785-2797. doi: 10.1111/gcb.15059. Epub 2020 Mar 25.
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 (HC) community structure already evident across broad spatial scales. While several underlying relationships between HC 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 HC mortality. This unprecedented sequence of disturbances was used to estimate the effects of discrete versus interacting disturbances on the compositional structure of HC, soft corals (SC) and algae. Discrete disturbances increased the prevalence of algae relative to HC while the interaction between cyclones and heat stress was the main driver of the increase in SC relative to algae and HC. Predictions from disturbance scenarios included relative increases in algae versus SC that varied by the frequency and types of disturbance interactions. However, high uncertainty of compositional changes in the presence of several disturbances shows that responses of algae and SC to the decline in HC needs further research. Better understanding of 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.
预测生态系统动态的未来变化需要了解其关键群落如何应对当前的环境格局。大堡礁（GBR）正受到威胁，其造礁硬珊瑚（HC）群落结构已经在广泛的空间尺度上发生了迅速变化。虽然已经记录了 HC 与多种干扰之间的一些潜在关系，但其他底栖群落对干扰的反应还不是很清楚。在这里，我们使用统计建模来探索与气候相关的广泛规模干扰对底栖群落的影响，以预测在干扰频率增加的情况下它们的结构。我们使用 2012 年至 2017 年间在大堡礁北部进行的 14.5 万次观测估计的底栖群落组成来参数化一个多元模型。在此期间，调查的珊瑚礁受到两次热带气旋和两次热应激事件的不同程度影响，导致广泛的 HC 死亡。这种前所未有的干扰序列用于估计离散干扰与相互作用干扰对 HC、软珊瑚（SC）和藻类组成结构的影响。离散干扰增加了藻类相对于 HC 的流行度，而气旋和热应激之间的相互作用是 SC 相对于藻类和 HC 增加的主要驱动因素。干扰情景的预测包括藻类相对于 SC 的相对增加，这因干扰相互作用的频率和类型而异。然而，在存在多种干扰的情况下，组成变化的高度不确定性表明，藻类和 SC 对 HC 减少的反应需要进一步研究。更好地了解多种干扰对整个底栖群落的影响对于预测珊瑚礁的未来状况以及根据新的环境状况进行管理至关重要。我们在这里开发的方法为实现这一目标开辟了新的机会。
