The Role of Live and Dead Corals in Shaping Fish Assemblages Across Life Stages

Coral reef fishes face unprecedented threats, as extensive habitat degradation compromises their ecological functions by modifying assemblage structure. It remains unknown how resistant reef fishes are to widespread losses in coral cover, and most studies tend to focus on adults, overlooking the important role of recruits. This study employed taxonomic and trait-based approaches to investigate how live and dead branching corals influence reef fish assemblages across life stages. Over 1 year, we monitored recruitment and the migration of post-recruits (juveniles and adults) on manually constructed 1 m² patches of live and dead branching corals in a degraded reef. Recruit assemblages, composed mainly of two trophic groups, exhibited similar abundance and richness in the complex structures of dead and live coral patches, compared to flat control patches. Conversely, post-recruit fishes were more abundant, species-rich, and functionally diverse in live coral patches, encompassing several trophic groups and displaying a dominance shift between mobile and sedentary species. Our findings reveal that while dead coral structures can serve as temporary shelters for mobile recruits, live corals are essential for supporting long-term biodiversity and diverse functional traits. This study underscores the complementary roles of both live and dead corals in promoting reef fish recovery and highlights the value of integrative strategies for reef ecosystem restoration.