Predicting Coral Offspring Survival From Reef Thermal Histories in Ningaloo World Heritage Reef

Identifying coral populations with heritable thermal tolerance is critical for developing climate-resilient reef conservation practices. We quantified thermal tolerance in larvae from 51 selectively bred Acropora families using acute heat stress assays (35.5°C) then modelled larval survival against 20 satellite-derived SST predictors (1985-2022) using boosted regression trees (BRT) to predict the spatial distribution of thermally resilient coral offspring along Ningaloo World Heritage Reef (East Indian Ocean). BRT models had an AUC of 0.67 (±0.01 SE) and revealed that thermal anomaly frequency, cumulative heat stress and temperature variability, particularly diurnal temperature range, most strongly predicted larval survival (37.2%, 22.7% and 21.7%, respectively). Survival peaked at thermal stress of 1.14°C -weeks (Degree Heating Weeks) and variability of daily temperature range of ~1°C day^-1 highlighting potential ecological thresholds in larval survival in this area. Spatial outputs identified six reefs (17% of surveyed sites), all north of Point Cloates, as having the highest predicted larval survival (> 45%), contrasting with consistently lower survival probabilities across most southern sites. By linking experimental physiology with spatial modelling, this study delivers the first spatially explicit predictions of thermally resilient larval supply along Ningaloo Reef, providing a scalable framework for guiding marine spatial planning, broodstock selection and restoration prioritisation across a remote World Heritage coral reef.