Long term state of coastal lagoons in Veracruz, Mexico: Effects of land use changes in watersheds on seagrasses habitats

• Over the past 50 years, the health condition of coastal ecosystems in Central Veracruz, Mexico, has declined.
• The accelerated increase in population and economic activities, lead to eutrophic conditions that persist until present.
• Wetlands and seagrasses have reduced their cover and biomass, being far more severe for seagrasses.
• Seagrass species adapted to eutrophic conditions are the only ones present, such as Halodule wrightii and Ruppia maritima.
• Management regulations need to be established, considering all activities at the watershed level.

An increase in population over the last 50 years along the central coast of Veracruz on the Gulf of Mexico has led to a corresponding intensification of agriculture, urbanization, and other economic activities. Most significantly, this has resulted in rapid changes of land use and an increase in the area dedicated to agriculture and livestock. Native coastal wetland vegetation has declined significantly, and coastal lagoons systems are altered as they receive excess nutrients and sediments from agricultural and economic activities. The aim of this study was to evaluate the influence of productive activities on four coastal lagoons and one estuary at the watershed level and to establish reference points or ecological indicators upon which future changes in coastal wetlands may be measured. For this purpose we analyzed the physico-chemical characteristics of the water column, assessed the abundance and biomass of seagrasses, and determined the historical and current trophic status of these coastal water bodies. Our results indicate that over time the lagoons have remained in a eutrophic state, and only one has become mesotrophic. The biomass of the seagrass Halodule wrightii decreased by 28% from 1991 to 2001 in La Mancha Lagoon. Our results provide a baseline to assess future changes in the water quality of the selected study sites and the seagrasses populations they contain.