Laguna de Términos
Laguna de Términos is the largest tidal lagoon by volume located entirely on the Gulf of Mexico, as well as one of the most biodiverse. Exchanging water with several rivers and lagoons, the Laguna is part of the most important hydrographic river basin in Mexico. It is important commercially, as well as ecologically by serving as a refuge for an extensive number of flora and fauna; its mangroves provide an important role as a refuge for migratory birds. History. The Boca de Términos was discovered during Juan de Grijalva's expedition in 1518. Environment. Geography. Laguna de  Términos ("Lagoon of Ends", as it is the end of regional rivers) is made up of a series of rich, sediment-laden lagoons and tidal estuaries connected by two channels to the Bay of Campeche in the southern part of the Gulf of Mexico, in Carmen Municipality in the southwestern part of the Mexican state of Campeche. Its shores are swampy and support mangroves. It is fed by several freshwater rivers, including the Mezcapala, Grijalva and Usumacinta Rivers, and includes several lagoons such as Pom, Atasta, Puerto Rico, Este and Panlau. It is long, wide, and covers an area of  . Every nine days, approximately 50% of the lagoon's water volume is renewed, primarily through the effect of ocean tides. On the surrounding barrier islands, beach ridges, and mangrove coastline there are several Late Postclassic Maya sites. The city of Ciudad del Carmen is located on Isla del Carmen, between the lagoon and the Bay of Campeche. Flora and fauna. Twenty-nine percent of the lagoon is covered with seagrass. The lagoon was designated as a federally protected area for flora and fauna in 1994 by the Mexican government because of the importance of the biological ecosystems provided by its  estuaries. There have been 1,468 identified fauna species found within the protected area of Laguna de Términos; 30 species are endemic to Mexico and 89 are threatened; 132 species are considered to be commercially important. There are 279 bird, 74 insect (considered an incomplete listing), and 34 mammal species identified. At least 367 species of fish are listed. It is a known breeding and nursery area for the yellow stingray ("Urobatis jamaicensis"); seagrass is reported to be important for its parturition. Campeche and Tabasco hold wetlands consisting of mangrove zones, swamps, and lagoons serving as important habitats for aquatic reptiles  such as crocodiles (American, Morelet's, brown caiman). Nationally endangered hawksbill, green sea, and Kemp's ridley sea turtles come on sandy shores to lay eggs especially setting a special protection on Kemp's ridley turtles. Mangroves around the Lagoon of Términos provides a migratory collider for at least 33% of the Mississippi - migratory birds. Of about 134 mammalian species from 27 families present in the area, rare and endangered species include felines (jaguar, ocelot, margay), primates (Geoffroy's spider monkey), and marine mammals including cetaceans and the West Indian manatee. Bottlenose dolphins. Bottlenose dolphins ("Tursiops truncatus") are known to  visit the lagoon regularly, but their safety could be endangered due to several artificial factors. A conservation group called Instituto Via Delphi which is specially designed for protection of local dolphins along Mexican gulf regions were founded to focus understanding of biology of these dolphins and to strengthen their protection. Threats. The biggest influence on the area and a possible threat are the operations of state-owned oil company, Pemex operating within the protected area. The drilling of oil wells and the construction of pipelines can destroy habitat. Additionally, oil spills are a continual threat. Other possible threats include habitat  change through population growth in the surrounding area. Laguna de Términos Flora and Fauna Protection Area as a whole is considered to be critically threatened. Although Pemex is both the biggest influence and the biggest threat to the protected area and its biodiversity, it is also economically important to Mexico. Currently there is a petroleum boom which presents an opportunity for the management of the protected area to offer to cooperate with the industry and coordinate use of the resources. There are local residents and non-governmental organizations who are aware of the potential problems and who are a strong  voice, with public protests against Pemex plans that emphasize the destruction to ecosystems and quality of life at other Pemex locations. Pemex has acknowledged that they must take into account the opinions of the protected area's management and other voices when planning projects so as to minimize negative environment impacts. Local populations of crocodiles and sea turtles in the areas are in serious danger due to their value for commercial industries.