International Journal of Marine Science, 2025, Vol.15, No.4, 220-232 http://www.aquapublisher.com/index.php/ijms 228 mangroves not only bury carbon itself, but also transport some organic debris and dissolve organic carbon to nearshore water bodies through tides. A considerable portion of these organic matter settles in adjacent seagrass beds and tidal flats, and continues to be buried (Yuan et al., 2022). Therefore, protecting mangroves helps maintain an organic carbon supply to downstream seagrass beds and mudflats. In addition, different wetlands are also complementary in the time scale of carbon sequestration: mangroves fast carbon sequestration rates and soil carbon turnover are relatively fast, seagrass bed carbon sequestration rates are slightly lower, but the carbon reservoir formed is more stable. The combination of the two can improve the stability of carbon sinks throughout the region (Wang and Liu, 2024). Therefore, in practice, linkage recovery has become an important strategy. Seagrass bed restoration is mostly carried out in appropriate water depths outside the mangrove forest. By transplanting seagrass algae clusters, conditions are created for mangrove forests to filter water quality and accumulate sedimentation. During the pilot projects in Florida, the United States and Guangdong, China, after mangroves, salt marshes and seaweeds in the same bay were restored at the same time, the carbon sink effect of the overall ecosystem was significantly improved. In addition to carbon sinks, this measure also brings synergistic gains in ecosystem services: the connected wetland network provides a "life corridor" throughout mangrove-seagrass-coral reefs for wild animals such as fish and shrimp, which is conducive to biodiversity; at the same time, the existence of multiple ecological barriers also enhances the protection function of coastline against storms and erosion (Saavedra-Hortua et al., 2023). 6.3 Case analysis: construction of the mangrove ecological corridor in Beihai, Guangxi, China In Beihai City, Guangxi, China, an ecological restoration practice combining mangroves with other wetland systems provides an example for comprehensively improving carbon sink capacity. The Beihai is located along the Beibu Gulf coast and has a variety of wetland ecosystems such as mangroves, seagrass beds and coastal tidal flats. In the past, due to urban development and pollution, mangroves in some shore sections of the North Sea fell and deteriorated, the Yintan shoreline was broken and not connected, and the ecological function of wetlands was significantly reduced. To reverse the situation, Beihai City has implemented a large-scale "land-sea coordination" ecological restoration project since 2017. One of the core measures is to build a mangrove ecological corridor and connect urban rivers, wetland parks and coastal mangroves into one (Sun et al., 2025). At the same time, the restoration project also carried out the restoration of Yintan beach shoreline and the protection of seagrass beds, ultimately realizing ecological connectivity between rivers and forests and beaches (Figure 3). After several years of hard work, Beihai City has restored about 370 mu of mangrove forests and artificially replanted 270 mu of mangrove seedlings, connecting the once broken mangrove areas into a nearly 4.5-kilometer-long coastal shelterbelt (Wu et al., 2022). After the ecological corridor is opened, the carbon sink function of the system is significantly enhanced. On the one hand, the overall health of continuous mangroves has improved: due to the reduction of freshwater runoff pollution and clearer water quality, mangrove growth has become more vigorous, and the survival rate of artificially planted mangroves in some areas has increased from less than 20% to more than 50%. The forest soil gradually returned to its silt state, and the newly deposited peat layer steadily increased the soil carbon content per unit area. On the other hand, biodiversity has increased significantly and mangrove ecosystems have become stable. Monitoring shows that the number of bird species recorded in the project area increased from 136 in 2017 to 171 in 2020. Most of the new species were wadering birds and shorebirds, including critically endangered spoon-billed sandpipers and other migratory birds. The success of the construction of Beihai mangrove ecological corridor lies in the fact that it coordinates urban pollution control, mangrove restoration and coastline improvement. Through the coordinated restoration of multiple ecosystems, it has achieved the goal of "clear water, rich forests and beautiful beaches". 7 Construction of Monitoring and Evaluation System 7.1 Application of satellite remote sensing and drone monitoring technology To effectively enhance and maintain the carbon sink function of mangroves, a complete monitoring and evaluation system must be established to track the scope changes, growth status and carbon reserves of mangrove ecosystems for a long time. The development of modern remote sensing technology provides a powerful tool for large-scale and high-frequency mangrove monitoring. Among them, satellite remote sensing has been widely used in
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