Dynamic patterns of constraints, drivers and impacts of land-based aquaculture areas and their implications: A case of Guangdong, China from 1990 to 2020

The expansion of land-based aquaculture areas (LAA) provide high-protein, nutritious food but also pose a threat to ecosystems. Understanding internal constraints, external drivers, and its impacts on land use is crucial for effective management policies of LAA. However, systematic research incorporating the aforementioned aspects remains lacking, which hinders us to present a comprehensive implication for the sustainability of LAA. To bridge this gap, leveraging the Google Earth Engine big data platform and geographic information technology, this study extracted long-term LAA distribution data, and quantified the dynamic patterns of natural constraints, socioeconomic drivers, and impacts for the first time. Guangdong, with a rich history in Chinese aquaculture, is the chosen study area. We find that: (1) Guangdong's LAA underwent rapid expansion (1990 −2000), steady expansion (2000 −2010), and slow shrinkage (2010 −2020). (2) During rapid expansion, precipitation and distance from lake are major constraints, the primary industry is main driver. The constraint of distance from lake gradually surpasses distance from the sea, resulting in the highest percentage of inland waters encroached at 72.27 %. In this period, LAA with high precipitation and near lake are easier to achieve rapid growth, demanding attention to water protection at the same time, particularly eutrophication of water bodies. (3) During steady expansion, constraints remained stable, and the major driver shifted from the primary to the secondary industry, resulting in a higher percentage of cropland encroached at 59.01 % compared to water. Increasingly, the focus is on the necessity of high-quality LAA development and cropland protection, especially the problem of soil salinization. (4) During slow shrinkage, constraints of distance from river and temperature became apparent, with the major driver shifting from the secondary to the tertiary industry, further increasing the percentage of cropland encroached to 62.78 %. In this stage, sustainable development relies on extending industry chain and innovative technology, and with continued emphasis on cropland and soil protection. These findings and implications provide a valuable reference for sustainable aquaculture development and resource and environmental management in global coastal regions.