Global mapping of human-transformed dike-pond systems

Human-transformed agricultural and aquacultural ponds, collectively referred to as "dike-pond systems", play a crucial role in ensuring food security but also contribute to the widespread loss of natural wetlands. However, spatially and temporally explicit patterns of dike-pond systems have not been thoroughly documented globally. Here, we map the distribution of dike-pond systems over both global inland and coastal regions during three periods (1984 to 2000, 2001 to 2010, 2011 to 2020) using 30-m resolution satellite observations. Results show that the total area of dike-pond systems was 132,886 km² globally, with about 2/3 contributed from inland wetlands. From 1984 to 2020, the net gain of inland dike-pond systems (26,385 km² or 92.7%) was 1.6 times that of coastal wetlands (16,371 km² or 83.3%), due primarily to reduced coastal dike-pond systems in the last decade. We identified significant contributions of dike-pond systems to fishery production, and further revealed occurrences of dike-pond systems within protected areas. Our study highlights the importance of prioritizing the conservation and management of more intensively inland dike-pond systems, and our global synthesis provides a critical benchmark for assessing potential consequences of dike-pond system and for future restoration efforts.