Understanding why some corals resist bleaching during marine heatwaves remains a central challenge for predicting reef resilience. Here, we leverage a large-scale field experiment comprising 60 artificial patch reefs on the northern Great Barrier Reef to test whether pre-disturbance ecological conditions influence coral responses to thermal stress. Patch reefs were established in November 2022 and monitored through time, with coral growth and fish community structure quantified prior to a region-wide bleaching event during the austral summer of 2023–2024.
The bleaching event provided an unplanned opportunity to assess coral resistance and survival within a spatially replicated experimental framework in which key ecological predictors were measured before thermal stress occurred. Coral fragments (Acropora millepora) were tracked across four timepoints spanning pre-bleaching, peak bleaching, and recovery phases. Fish biomass, colony size, and environmental covariates were quantified at the patch reef scale.
Substantial variation in bleaching severity and survival was observed among reefs, despite exposure to a shared regional heat stress event. Here, I present results of analyses testing whether this variation is explained by differences in pre-disturbance fish communities, coral condition, host genetics, symbiont community composition, and local environmental context. These findings provide rare experimental insight into the role of biotic interactions in mediating coral responses to climate-driven disturbance and highlight the potential for local ecological processes to influence reef resilience under global change.