Differential Regulation of Hydrodynamics and Anthropogenic Mariculture Activities on the Fate of Sedimentary Organic Carbon

Abstract The spatial evolution of sedimentary organic carbon (OC) along transport pathways reflects burial and remineralization processes, traditionally attributed to hydrodynamic transport. However, direct evidence verifying the mechanism or examining whether the evolution pattern can be disrupted particularly by the input of marine OC from anthropogenic sources remains limited. This study integrates sediment resuspension experiment with sediment and OC characteristics analyses to elucidate hydrodynamic regulation on OC and additional mariculture‐induced variability. Hydrodynamic resuspension regulates OC content through grain‐size and mineral sorting but does not directly alter its thermochemical properties, regardless of hydrodynamic intensity. In comparison, mariculture directly modulates OC content and properties by the input of labile OC. We address a previously overlooked aspect of the thermochemical properties of mariculture‐derived OC and underscore the importance of comprehensively evaluating the impacts of mariculture activities on OC, particularly regarding their long‐term biogeochemical consequences.