Knowledge of a species’ abundance is critically important for assessing its risk of extinction, but for the vast majority of wild animal and plant species such data are scarce at biogeographic scales. Here, we estimate the total number of reef-building corals and the population sizes of more than 300 individual species on reefs spanning the Pacific Ocean biodiversity gradient, from Indonesia to French Polynesia. Our analysis suggests that approximately half a trillion corals (0.3 × 10¹²–0.8 × 10¹²) inhabit these coral reefs, similar to the number of trees in the Amazon. Two-thirds of the examined species have population sizes exceeding 100 million colonies, and one-fifth of the species even have population sizes greater than 1 billion colonies. Our findings suggest that, while local depletions pose imminent threats that can have ecologically devastating impacts to coral reefs, the global extinction risk of most coral species is lower than previously estimated.

了解一个物种的丰度对于评估其灭绝风险至关重要，但对于绝大多数野生动植物物种而言，此类数据在生物地理尺度上是稀缺的。在这里，我们估计了从印度尼西亚到法属波利尼西亚横跨太平洋生物多样性梯度的珊瑚礁上造礁珊瑚的总数和 300 多个个体物种的种群规模。我们的分析表明，大约五万亿珊瑚（0.3 × 10 ¹² –0.8 × 10 ¹²) 栖息在这些珊瑚礁中，与亚马逊河中的树木数量相似。三分之二的受检物种种群规模超过 1 亿个，五分之一的物种甚至超过 10 亿个。我们的研究结果表明，虽然局部枯竭构成迫在眉睫的威胁，可能对珊瑚礁造成生态破坏性影响，但大多数珊瑚物种的全球灭绝风险低于之前的估计。