Spatial-temporal variations and driving factors of coastal aquaculture ponds in China from 1985 to 2023.

As the world's largest marine aquaculture country, China accounts for over 60% of the global aquaculture total production. The development of coastal aquaculture is of great significance for ensuring food security in China and even globally. Meanwhile, it also affects the ecological environment of coastal wetlands. Based on remote sensing images and socio-economic data from 1985 to 2023, and in line with the scope of coastal wetlands defined by The Ramsar Convention, we adopted an object-oriented classification method to explore the spatiotemporal variations and driving factors of coastal aquaculture ponds in China (excluding Taiwan Province, the same below). The results showed that the area of coastal aquaculture ponds in China generally presented an increasing trend from 1985 to 2023. The growth rate was 68.3 km² per year from 1985 to 2010 and decreased to 17.1 km² per year from 2010 to 2023. From 1985 to 2023, aquaculture ponds in different typical coastal regions of China exhibited obvious spatial variations. Specifically, the areas of aquaculture ponds in Liaodong Bay, Bohai Bay and Beibu Gulf showed obvious expansion trends, while those in the Yellow River Delta, Pearl River Delta and Yangtze River Delta showed a trend of increasing first and then decreasing. The main sources of the expansion of aquaculture ponds were muddy beaches (38.8%), offshore waters (33.3%), and coastal wetland vegetation (14.1%). During the study period, there was a significant negative correlation between the area of mudflats and the expansion of aquaculture ponds, while built-up land, population size and GDP showed significant positive correlations with coastal aquaculture ponds. The expansion of coastal aquaculture ponds was mainly occupied coastal wetland, and it is necessary to coordinate the development and protection of coastal wetlands.