Effects of Desiccation-Rewetting Cycles on the Carbon Sequestration Capacity of Ulva pertusa

Dissolved organic carbon (DOC) and particulate organic carbon (POC) play essential roles in the carbon sequestration, with macroalgae being major producers of DOC and POC. The intertidal zone is the transition area between the ocean and the land, the main habitat of macroalgae. However, few studies have focused on the regulation of tidally induced desiccation-rewetting cycles on carbon sequestration by intertidal macroalgae. Therefore, we simulated the intertidal environments to investigate the effects of desiccation-rewetting cycles on the growth, DOC and POC release mechanisms of Ulva pertusa. After 14 days of experiments, the DOC release capacities of U. pertusa (per gram fresh weight) were 1.08, 5.31, 9.74 and 7.47 mg/g in the subtidal, low, middle and high tide zones, respectively. The corresponding POC release capacities were 0.04, 1.00, 3.90 and 1.38 mg/g. Combined biological carbon sequestration, the total carbon sequestration capacities of U. pertusa in the subtidal, low, middle and high tide zones were 24.73, 32.84, 27.83 and 16.97 mg/g, respectively. The results indicated that the highest carbon sequestration capacity of U. pertusa occurred in low tide zones. In conclusion, the results will provide support for the application of seaweed negative emissions.