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.
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We thank many individuals for assistance with species identification and field surveys, particularly A. Baird, S. Blake, M. Boyle, H. Cornell, E. Dinsdale, R. Karlson, M. Kaspartov, P. Osmond and J. Wolstenholme. Major funding for this analysis was provided by the Australian Research Council’s Centre of Excellence Program (CE140100020) and a Laureate Fellowship to T.P.H. (FL120100063).
The authors declare no competing interests.
Peer review information Nature Ecology & Evolution thanks Hans ter Steege, Robert Steneck and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Supplementary Tables 1–2 and Figs. 1–7.
Supplementary Data 1: a table listing the abundance of 318 Indo-Pacific coral species by region and habitat type measured as number of intercepts. Supplementary Data 2: a table listing the estimated population sizes of 318 Indo-Pacific coral species and their current IUCN conservation status. Supplementary Data 3: a table listing the locations and sources of 61 compiled reef habitat maps.
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Dietzel, A., Bode, M., Connolly, S.R. et al. The population sizes and global extinction risk of reef-building coral species at biogeographic scales. Nat Ecol Evol 5, 663–669 (2021). https://doi.org/10.1038/s41559-021-01393-4
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