Coral degradation alters community diversity and stability of fish and invertebrate assemblages following recruitment

Habitat degradation is one of the most pervasive threats to coral reef ecosystems, and the intensification of global and local disturbances is expected to further exacerbate its impacts. While many studies have investigated the effects of coral degradation on fish and invertebrates separately, its impact on the settlement and recruitment of entire coral-associated communities remains poorly understood. To fill this gap, we experimentally quantified how coral status (live versus dead) and ecological process (settlement: after 7 d, and recruitment: after 28-30 d) shape the abundance, diversity and community composition of coral-dwelling organisms in the back reef of Mo’orea, French Polynesia. Live corals supported significantly higher abundance, species richness and Shannon diversity at the recruitment stage, whereas no differences were detected during settlement. Similarly, recruits on live coral exhibited lower compositional variability, fostering a more ecologically stable community over time. Both coral status and ecological process significantly influenced taxonomic and feeding guilds, although their effects were independent. Overall, our findings demonstrate that live corals provide structurally complex, resource-rich habitats that enhance biodiversity and promote the establishment of more stable and functionally diverse communities. Coral degradation, in contrast, disrupts these dynamics, affecting not only fish communities but the entire benthic assemblage associated with corals, altering key ecological functions and potentially reducing reef resilience. Understanding how coral degradation affects settlement and recruitment across taxa is essential for preserving healthy coral structures, which should be prioritized to sustain the ecological integrity and trophic functioning of reef ecosystems.