Reef-building coral assemblages are typically species-rich, yet the processes maintaining coral biodiversity remain poorly understood. Disturbance has long been believed to promote coral species coexistence by reducing the strength of competition. However, such disturbance-induced effects have since been shown to be insufficient on their own to prevent competitive exclusion. Nevertheless, Modern Coexistence Theory has revealed other mechanisms by which disturbance and, more generally, environmental variation can favour coexistence. Here, we formulate, calibrate, and analyze a size-structured, stochastic coral competition model using field data from two common colony morphologies. These two coral morphologies, tabular and digitate, differ in their size-dependent vulnerability to dislodgement caused by wave action. We confirm that fluctuations in wave action can promote coral species coexistence. However, using a recently proposed partitioning framework, we show that, contrast to previous expectations, temporal variability in strength of competition did not promote coexistence. Instead, coexistence was enabled by differential fluctuations in size-dependent mortality among competitors. Frequent and intense disturbances resulted in monocultures of digitate corals, which are more robust to wave action than tabular corals. In contrast, infrequent or weak disturbances resulted in monocultures of tabular corals. Coexistence was only possible under intermediate levels of disturbance frequency and intensity. Given the sensitivity of coexistence to disturbance frequency and intensity, anthropogenic changes in disturbance regimes are likely to affect biodiversity in coral assemblages in ways that are not predictable from single population models.

中文翻译：

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扰动引起的大小结构变化促进珊瑚生物多样性

建立礁石的珊瑚群落通常物种丰富，但是维持珊瑚生物多样性的过程仍然知之甚少。长期以来，人们一直认为干扰会通过降低竞争强度来促进珊瑚物种共存。但是，这种干扰引起的影响自此被证明不足以防止竞争排斥。然而，现代共存理论揭示了其他机制，干扰和更广泛的环境变化可以通过这些机制促进共存。在这里，我们使用来自两种常见菌落形态的实地数据来制定，校准和分析一种大小结构的随机珊瑚竞争模型。这两种珊瑚形态，板状和指状，在大小相关的易受波浪作用引起的脱位脆弱性方面有所不同。我们确认波浪作用的波动可以促进珊瑚物种的共存。但是，使用最近提出的分区框架，我们发现，与以前的预期相反，竞争强度的时间变化不会促进共存。取而代之的是，竞争者之间大小相关死亡率的差异波动实现了共存。频繁而强烈的干扰导致了指状珊瑚的单一养殖，与板状珊瑚相比，它们对波浪作用的抵抗力更强。相反，很少或很少的干扰导致平板珊瑚的单一养殖。仅在干扰频率和强度处于中等水平时才可能共存。考虑到共存对干扰频率和强度的敏感性，