Identifying variable changes in wetlands and their anthropogenic threats bordering the Yellow Sea for water bird conservation

Abstract

As critical habitats for migratory birds in the East Asia-Australasia Flyway, coastal wetlands bordering the Yellow Sea have experienced prominent losses and threats triggered by human activities. In this study, the spatially and temporally variable changes in wetland extent and anthropogenic threats bordering the Yellow Sea from 1978 to 2018 were examined by utilizing Landsat observations. A fishnet and an anthropogenic threat index (ATI) were applied to document the patterns of wetland changes and anthropogenic threats and further to reveal their interactions. The results indicated that natural wetlands bordering the Yellow Sea have undergone consistent losses during the past four decades, with a net decline rate of 17.2% (7361.2 km2). The ATI pattern suggested that direct anthropogenic threats from agriculture and urbanization distributed like a new Great Wall affecting the natural wetlands along the coastline, while built-up land consistently expanded on each side of the three countries (China, North Korea, and South Korea). The spatial distribution of bird number, night light data, and major ports, as well as the Landsat images, demonstrated that notable anthropogenic threats have affected coastal wetlands and biodiversity. Given these comparative findings, the study is expected to support policy optimization and international corporations in coastal wetland management to achieve the twin goals of biodiversity conservation and socioeconomic development.