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The population sizes and global extinction risk of reef-building coral species at biogeographic scales

An Author Correction to this article was published on 16 March 2021

This article has been updated


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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Fig. 1: The Indo-Pacific biodiversity gradient and the locations where coral abundance and reef habitat data were collected.
Fig. 2: Taxonomic and morphological composition of the Pacific coral fauna.
Fig. 3: The population sizes of Indo-Pacific coral species and their conservation status.
Fig. 4: Correlation between numerical abundance and the area occupied by each species.

Data availability

Data files for statistical analyses are available from the Tropical Data Hub ( at

Code availability

Computer code for statistical analyses is available from the Tropical Data Hub ( at

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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).

Author information




T.P.H. led the fieldwork and taxonomic training to collect the species abundance data. A.D., M.B. and T.P.H. developed the study concept and analytical framework. S.R.C. contributed to statistical analyses. A.D. led the writing with contributions from all authors.

Corresponding author

Correspondence to Andreas Dietzel.

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The authors declare no competing interests.

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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 information

Supplementary Information

Supplementary Tables 1–2 and Figs. 1–7.

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Supplementary Data

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 (2021).

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