Characteristics of microbial carbon pump in the sediment of kelp aquaculture zone and its contribution to recalcitrant dissolved organic carbon turnover: insights into metabolic patterns and ecological functions

Abstract

The study delves into the microbial carbon pump (MCP) within the sediments of kelp aquaculture zones, focusing on its influence on the turnover of recalcitrant dissolved organic carbon (RDOC). Following kelp harvest, significant alterations in the microbial community structure were noted, with a decrease in complexity and heterogeneity within co-occurrence networks potentially impacting RDOC production efficiency. Metabolic models constructed identified four key microbial lineages crucial for RDOC turnover, with their abundance observed to decrease post-harvest. Analysis of metabolic complementarity revealed that RDOC-degrading microorganisms exhibit broad substrate diversity and are engaged in specific resource exchange patterns, with cross-feeding interactions possibly enhancing the ecological efficiency of the MCP. Notably, the degradation of RDOC was found not to deplete the RDOC pool; as aromatic compounds break down, new ones are released into the environment, thus supporting the renewal of the RDOC pool. The research highlights the pivotal role of microbial communities in RDOC turnover and offers fresh insights into their cross-feeding behavior related to RDOC cycling, providing valuable data to support the future development and application of MCP theory.