Sediment resuspension events—caused by storms, waves, currents, dredging, or bottom trawling—move previously buried material back into the water column, altering the balance between carbon burial and carbon release. When sediments are disturbed, particulate organic carbon (POC) and associated reduced compounds are exposed to oxygen and microbial degraders, accelerating remineralization to dissolved inorganic carbon and, in many cases, respired CO2. Work by John J. Middelburg at Utrecht University emphasizes how physical disturbance controls the exposure and microbial processing of organic matter in coastal sediments, linking sediment dynamics directly to carbon turnover rates.
Mechanisms altering fluxes
Resuspension changes both the chemical environment and physical transport. Oxidative exposure increases microbial respiration of labile organic matter, converting solid-phase carbon into dissolved forms and gaseous CO2 that can evasion to the atmosphere. Finer particles rich in organic matter remain suspended longer and can be transported laterally, exporting carbon offshore or to deeper depositional areas where burial may or may not occur. The balance between enhanced remineralization and lateral export determines whether an event acts as a net source or sink for atmospheric CO2.
Ecological and human-context consequences
Carlos M. Duarte at King Abdullah University of Science and Technology has documented how disturbance of coastal vegetated habitats such as seagrass beds and mangroves reduces their role in long-term carbon storage, because resuspension increases turbidity, reduces light for photosynthesis, and undermines vegetation that stabilizes sediments. For coastal communities, this translates into risks for fisheries, water quality, and livelihoods where turbidity and habitat loss affect nursery grounds. Culturally and territorially, small island and low-lying coastal regions face amplified consequences because loss of blue carbon reservoirs undermines both local subsistence and nationally reported carbon budgets.
Management implications follow directly: minimizing anthropogenic resuspension from dredging and trawling, protecting vegetated shorelines, and restoring depositional environments can reduce CO2 release and enhance long-term sequestration. Accurate coastal carbon accounting must therefore include episodic resuspension dynamics and their cascading effects on microbial processing, lateral transport, and habitat integrity to assess whether coastal zones act as sources or sinks under changing climatic and human pressures.