Microbial structural shifts and enhanced carbon metabolism following coral restoration on Wuzhizhou Island, China

Global climate change and human activities are accelerating coral reef degradation, prompting extensive coral restoration efforts. However, how coral restoration influences microbial community structure and function remains unclear. We examined the ecological impacts of coral restoration on Wuzhizhou Island, Hainan, China, by comparing the microbial community structures and metabolic functions in seawater and sediment from natural, degraded, and restored sites. Results showed that microbial communities in both seawater and sediment were dominated by specific bacterial groups. Fluviicola was abundant in natural seawater, while Owenweeksia and Desulfosarcina were prevalent in fragmented areas. Candidatus Pelagibacter and Hyphomonas were abundant in restored areas. Bacterial richness, diversity, and interrelationships varied significantly across these environments. Restoration efforts markedly enhanced microbial carbon metabolism in seawater and sediment, with clear recovery in the citric acid cycle and pentose phosphate pathways. However, linear discriminant analysis effect size suggested an enrichment of pathogen-associated pathways in restored sediment, indicating that human-induced ecological disturbances could affect microbial metabolic functions in sediment. While coral restoration notably enhanced microbial community structure and carbon metabolism in seawater, sediment functional recovery was slower, highlighting the environmental complexities and challenges of restoring microbial functions in both environments and provided key insights for improving coral restoration strategies.