Thirty-four years of Landsat monitoring reveal long-term effects of groundwater abstractions on a World Heritage Site wetland.

Wetlands are among the most biodiverse yet endangered ecosystems on Earth. Despite being the most important wetland in Europe, the Doñana National Park (southwestern Spain) is no exception, and the increase of nearby groundwater abstractions for intensive agriculture and human supply has raised international concerns about the conservation of this iconic wetland. It is thus needed to assess wetlands' long-term trends and responses to global and local factors to make informed management decisions. In this paper, we used 442 Landsat satellite images to analyze the historical trends and drivers of the date of desiccation and maximum flooded area in 316 ponds located in Doñana National Park during a 34-year period (1985-2018) and found that 59 % of the ponds studied are currently desiccated. The use of Generalized Additive Mixed Models (GAMMs) showed inter-annual variation in rainfall and temperature as the most important factors determining pond flooding. However, GAMMS also showed that intensive agriculture and the nearby tourist resort were related to the desiccation or shrinking of ponds all over Doñana, finding that the strongest negative flooding anomalies (i.e. ponds flooding less than explained by climate alone) were located in proximity to pumping areas. These results suggest that current levels of groundwater exploitation may be unsustainable and require urgent measures to control abstractions to ensure the integrity of the Doñana pond network, and the persistence of >600 wetland-dependent species.