Patterns in Coral Fecundity Across the Indo-Pacific

Coral reproductive potential is a fundamental component of reef resistance and recovery, yet large-scale estimates of reproductive potential remain limited. This study generated the first large-scale approximation of coral reproductive potential across the Indo-Pacific by integrating coral fecundity, trait-based imputation, and coral cover data. Reproductive potential was estimated for 277 coral species from 55 genera, including key genera such as Acropora, Isopora, Montipora, and Porites, for a single, hypothetical spawning period. We combined empirical coral fecundity datasets with trait-based imputation approaches to estimate reproductive potential at three levels: fecundity per cm², colony fecundity, and total fecundity across the Indo-Pacific. These fecundity estimates were then integrated with regional coral cover to derive a first-order approximation of reproductive potential. The estimated total reproductive potential of Indo-Pacific corals was approximately three quintillion eggs (3.46 × 10¹⁸) for one hypothetical spawning period. Fecundity varied significantly across genera and growth forms, with Isopora, Acropora, and Montipora contributing disproportionately to total egg production (mean totals of 3.9 × 10¹⁶, 4.2 × 10¹⁵, and 3.49 × 10¹⁵ eggs, respectively). Branching and massive growth forms collectively accounted for roughly 50% of total fecundity across all levels. Species-level fecundity was not consistently aligned with genus-level trends, with some species exhibiting exceptionally high fecundity at the species level despite relatively low average fecundity at the level of genus. Concordance across the three fecundity levels was low, highlighting substantial variation within genera and potential gaps in our current understanding of coral reproductive potential, likely both. This study provides the first quantitative approximation of Indo-Pacific coral reproductive potential, demonstrating high variation across species, genera, and growth forms. These findings underscore the importance of multi-scale reproductive assessments and offer a data-driven foundation for identifying key taxa for conservation or restoration efforts based on their disproportionately high contribution to reef recovery.