Landscape Changes in a Critical Subtropical Coastal Wetland in Northwestern Mexico: Is Shrimp Farming a Driver of Concern?

Abstract Coastal wetlands are critical ecosystems that are under intense pressure due to anthropogenic activities. In addition to urban growth and agriculture, shrimp farming has become one of the main drivers behind the loss of tropical and subtropical coastal wetlands. Despite its socio-economic importance, shrimp farming has high environmental costs worldwide. Consequently, it is essential to monitor shrimp farming at regional and local scales to determine if the resulting pressure on coastal wetlands is increasing. We analyzed land use/land cover (LULC) in the Bahía Santa Maria-La Reforma (BSMR) lagoon system in northwestern Mexico using remote sensing data to determine landscape and surface cover changes. We also projected future scenarios based on stochastic models and evaluated landscape metrics considering the effects of shrimp farming. Four LULC thematic maps (1985, 1994, 2002, and 2017) with overall accuracy values > 80% and two projected maps (2027 and 2037) were produced. Agriculture was the dominant LULC class in the BSMR coastal lagoon system, although saltmarshes appear as the most critical wetland type in the area. Shrimp farming, which was nonexistent in 1985, represented 4% of the total landscape in 2017. By 2037, this value is expected to increase to 5%. Saltmarshes showed negative trends due to the expansion of shrimp farming. Considering the importance of wetlands given their ecosystem services, this study highlights LULC changes due to economic activities and the need to improve management strategies to protect the wetlands of the BSMR coastal lagoon system.