Propagation method and species drive survival patterns across reef zones in coral seeding on the Great Barrier Reef

Abstract Introduction Coral reef restoration increasingly relies on scalable methods, yet outcomes vary across species, propagation techniques, and habitats. Coral seeding, where coral propagules are settled on deployment units before outplanting, provides a flexible approach that accommodates both asexual (e.g. microfragments) and sexual (e.g. spat) propagation. Objectives To improve predictability and efficiency of coral seeding, this study tested how propagation method, species, and habitat shape early survival. Methods A multi‐species coral‐seeding experiment was conducted at Davies Reef (central Great Barrier Reef), deploying microfragments and spat on seeding devices across 10 sites spanning lagoon, back, flank, and front reef zones. Survival was monitored for approximately 10 months. Analyses included time‐to‐mortality, growth, and generalized mixed models testing the effects of reef zone, water flow, benthic composition, and spat density. Results Microfragments outperformed spat in survival and reached approximately 10× larger mean size, relative to initial size. Species effects were zone‐specific. Spat survival declined at exposed flank and front sites, whereas microfragment survival was largely unchanged across zones. Reef zone improved model fit relative to flow alone, while site‐level benthic composition did not predict survival. Microhabitat effects accounted for approximately 30% of variance, with higher survival on substrates dominated by crustose coralline algae. Positive density dependence was detected for Galaxea fascicularis and Montipora turtlensis , but not for Acropora loripes . Conclusions Propagation method, species, and reef zone jointly shape coral survival, but centimeter‐scale microhabitat factors are key. Microfragmentation provides more reliable early survival and growth, whereas spat contribute genetic diversity.