Investigation into the Evolution Characteristics and Driving Factors of Seagrass Beds in Sanggou Bay (1985–2022)

Seagrass beds are crucial coastal ecosystems, functioning as vital blue carbon sinks and natural ecological barriers. However, these ecosystems are increasingly threatened by global climate events, coastal development, and water eutrophication, making them some of the most endangered ecosystems worldwide. In the Yellow Sea and Bohai Sea regions, seagrass bed assessment and monitoring have been largely overlooked. Thus, strengthening research efforts is necessary to identify current distribution patterns and long-term changes in seagrass bed resources. This study focused on a seagrass bed in Sanggou Bay, Rongcheng, using remote sensing (RS) and geographic information system technologies to analyze multisource satellite data from the US Landsat and Chinese resource satellite series. By combining RS indexes with historical survey data, large-scale temporal and geographic distribution data for seagrass beds were obtained in the study area from 1985 to 2022. The spatial distribution and evolution trends of the seagrass bed were analyzed using a water depth inversion model, and the factors driving its degradation were identified. Results indicated that the seagrass bed area in Sanggou Bay fluctuated between 100 and 140 km² from 1985 to 2010. During 2010–2013, dynamic changes in the seagrass bed area increased, with a considerable decrease in its overall size. After 2014, changes were minimal, indicating a notably stable state. Seagrass bed degradation in Sanggou Bay is influenced by high-intensity human activities, pollution from coastal land sources, raft cultures, underwater terrain conditions, and sedimentary environmental factors. The findings offer essential insights for developing seagrass restoration and protection strategies in Sanggou Bay and contribute to the broader scientific efforts for coastal ecosystem conservation and rehabilitation.