Two decades of coral carbonate production within and across geomorphic zones

Abstract While reef resilience is widely studied, there is increasing recognition of the need to assess it through carbonate production estimates. This study investigated gross carbonate production on Heron Reef (southern Great Barrier Reef) over a 20-year period, examining responses to environmental disturbances and the role of key benthic taxa. Drawing on data from over 30 sites across four geomorphic zones, we identified branching Acropora , tabular Acropora , and plating/encrusting Acroporidae as the primary contributors to carbonate production due to their high abundance, fast growth rates, and elevated CaCO 3 output. Heron Reef’s average annual production rate of 18.45 kg CaCO 3 /m 2 /year places it among the more productive clear-water reefs in the Indo-Pacific. A strength of this study lies in its spatial and temporal scope, providing a refined understanding of how disturbances shape reef-building capacity across zones. Heron Reef showed strong resilience, with rapid carbonate production recovery following major events, although sharp declines were recorded during severe bleaching, such as in 2024. This analysis focused on carbonate production and does not incorporate direct bioerosion measurements, which are necessary to calculate full carbonate budgets and long-term reef accretion potential. Future work should address this gap by integrating erosion data to improve estimates of net production. Nonetheless, this study offers valuable insight into the ecological processes supporting reef resilience. It underscores the importance of high-resolution, long-term datasets for understanding carbonate dynamics and informing targeted conservation strategies in the face of accelerating climate change.