Bacteria-archaea metabolic complementarity as a driver of ecosystem functioning in Chinese coastal sediments

Multivariate statistics identified organic carbon, oxygen, and sulfur availability as key drivers of microbial community structure. Co-occurrence network and functional profiling uncovered distinct ecological divergence: bacteria dominate oxidative processes including nitrogen and sulfur cycling as well as organic matter degradation, while archaea, predominantly <i>Bathyarchaeia</i>, occupy modular anaerobic niches specialized in methanogenesis and reductive pathways. This functional complementarity sustains integrated biogeochemical cycling in dynamic marine sediments. Our study advances understanding of prokaryotic community responses to vertical environmental gradients and their ecological roles in coastal sediment biogeochemical cycling.