Ecosystem Functioning and Sustainable Management in Coastal Systems With High Freshwater Input in the Southern Gulf of Mexico and Yucatan Peninsula

Abstract The southern Gulf of Mexico is characterized by coastal ecosystems with high freshwater input, extensive wetlands and coastal lagoons, productive fisheries, and human settlements whose economy is largely based on the rich natural resources of the area. The Grijalva-Usumacinta River and delta region has high riverine input and extensive wetlands. The CENTLA Biosphere Reserve was established to protect this important region. The management plan is based on the identification of natural environmental units that are grouped into two nucleus zones with high levels of protection and a number of buffer zones designed to allow some economic activities. Laguna de Terminos, the largest lagoon-mangrove system in Mesoamerica, has a long history of scientific study. The system has a high habitat diversity. Primary producers have peak production at different times of the year leading to overall sustained high productivity throughout the year. There is a high diversity migratory nekton community that uses the lagoon habitats at times when they are most productive ensuring overall high secondary production that supports a multistock fishery. The area has been designated as a natural protected area to ensure sustainable management. The coastal zone of the Yucatan Peninsula is fed by the extensive ground water system that supports a unique system of karstic freshwater lakes, brackish lagoons, estuarine coastal lagoons, and reef lagoons with extensive mangrove swamps and submerged aquatic vegetation. The main source of inorganic nutrients is ground water and in some parts of the coast elevated levels have the potential to cause eutrophication and harmful algal blooms. Along the northern and eastern coasts of the Yucatan, rapid development has led to extensive habitat degradation and water quality problems. Ecosystem-based management could lead to improved environmental quality and restoration. Some global climate models suggest that this region will experience strong decreases in precipitation and this may become the most serious problem for this region. Mexico has established 17 natural protected areas in the southern Gulf of Mexico and Yucatan to enhance sustainable management in the region. In this chapter we review the structure and functioning of this regional coastal system, describe human impacts, review sustainable management of the area, and discuss the potential impacts of climate change.