Multi-Trophic Interactions Drive the Coupling of Carbon, Nitrogen, and Sulfur Cycling During Mangrove Leaf Litter Decomposition
Mangrove ecosystems are hotspots for biogeochemical cycling. How multi-trophic benthos interactions drive coupled carbon, nitrogen, and sulfur cycling at the litter-sediment interface is unclear. We solved this problem via in-situ litter decomposition and multi-omics analyses of Kandelia obovata mangroves in the Jiulong River Estuary. We found that: (1) In litter layers, meiobenthos link macrobenthos with sulfur-cycling functional bacteria. In sediments, free-living sea nematodes mediate synergies between macrobenthos and anaerobic microbes. (2) In litter layers, functional gene networks present seasonal sulfur metabolism shifts: oxidation in summer and reduction in winter. Core genes (narG, dsrA, mcrA) drive coupled elemental cycling in sediment. (3) The interaction of benthos on the leaf litter drives the release of condensed tannins , altering sediment properties and suppressing C, N, and S cycling genes. These results offer new insights into coastal wetland carbon sink evolution under climate change.