Marine ranching seq

Artificial reefs (ARs) are widely employed in marine ranching to restore ecosystems and enhance primary productivity. These structures may influence the sediment microbial community that sustain the microbial carbon pump (MCP). Although the MCP serves as a critical mechanism for generating recalcitrant dissolved organic carbon (RDOC) and contributes significantly to global climate mitigation, the specific processes and efficiencies of the MCP within AR environments remain poorly understood. To address this knowledge gap, we conducted an integrated analysis using full-length 16S rRNA sequencing and metagenomics to compare sediment microbial communities, dissolved organic matter (DOM) composition, and MCP-related processes between AR areas and non-reef (NR) control sites. Results demonstrated that AR markedly altered microbial community structure and reconfigured the concentration and composition of DOM. Metagenomic analysis revealed that the reef environment enlarges intracellular acetyl-CoA pools and activates the mevalonate pathway, thereby promoting the synthesis of isoprenoid and CRAM-like RDOC precursors. We identified a substrate-driven mechanism whereby copiotrophic bacteria channel rapidly cycling organic carbon into more stable molecular forms, supported by strong correlations among polysaccharide degradation, central carbon metabolism, and mevalonate pathway completeness. Furthermore, metabolic complementarity and predicted cross-feeding interactions indicate that the MCP is a community-integrated process, reliant on cooperation between functional guilds with distinct carbon utilization capacities. In summary, this study demonstrates that AR create distinct biogeochemical niches that amplify MCP activity through coordinated shifts in microbial composition, metabolic fluxes, and ecological interactions, highlighting their potential as an effective ecological engineering pathway for enhancing coastal carbon sequestration.