Wetlands along the Mexican side of the Gulf Coast of Mexico (Region 29*) encompass 2,970 km of littoral wetland habitat. They consist of numerous large complexes of fresh, brackish and salt marshes and mangrove swamps. These areas are negatively impacted by several major human-induced factors (oil drilling, dredging, shipping, agriculture and urban development) and natural events (hurricanes, flooding, etc).
There are five wetland areas that make up the most important habitats for wintering and resident waterfowl: Laguna Madre in Tamaulipas (including the Rio Grande Delta), Tamiahua and Alvarado Lagoons in Veracruz, Centla Wetlands in Tabasco and the complex of wetlands in Campeche-Yucatan.
This hypersaline coastal lagoon encompasses over 200,000 ha of shallow water, flats and shoalgrass beds that provide excellent habitat for several waterfowl species, particularly the redhead. There are 41,975 ha of sea grasses and algae, of which 33,776 ha are monotypic beds of shoalgrass (Carrera and de la Fuente 1994). During the 1970s, the mean biomass of shoalgrass in the Laguna Madre was estimated to be 413.7 g/m2 (Cornelius 1975). Due to lowered salinity caused by construction of permanent channels along the barrier island and other dredging activities, shoalgrass has been reduced by about two-thirds (Mora 1994), with the subsequent reduction of carrying capacity for wintering waterfowl. There are also 36,330 ha of freshwater wetlands that are important to wintering waterfowl along the Laguna Madre (Carrera and de la Fuente 1994).
DU has worked to provide information to support the designation of the Laguna as a Federally Protected Area, but economic interests and development prospects have prevailed with the government of Tamaulipas and the area remains unprotected.
Tamiahua and Alvarado Lagoons
These areas are located in the state of Veracruz and measure 100,000 and 251,661 ha, respectively. Depending on local topography, they are a mosaic of mangroves, tropical flooded deciduous forest, and rain forest. In the Alvarado lagoon, the human population is mainly engaged in fishing activities. Nevertheless, cattle and other agricultural activities have caused the loss of almost all-natural vegetation. The lagoon system still contains vast mangrove communities and shallow lagoons with submerged and floating vegetation. The major threats are pollution from urban developments, sugar cane factories, paper, cellulose and other textile industries, beer factories and tanneries.
Twelve percent of the state of Tabasco is protected as a Biosphere Reserve, which represent the most important freshwater resources in Mexico. The reserve is 302,706 ha; of which 1/3rd is considered to be the nucleus and 2/3rd is a buffer zone. Of the total area, 20% is permanently flooded freshwater delta wetlands formed at the confluence of the Grijalva and Usumacinta Rivers.
Campeche and Yucatan Lagoons
Within these two states, three protected areas have been established. Two are state reserves: the Petenes in Campeche and El Palmar in Yucatan, which are 68,000 and 59,177 ha in size, respectively. The third reserve is 85,474 ha and has been designated federally as the Celestun Special Biosphere Reserve in Yucatan. Wetlands of the Yucatan Peninsula are typically long, narrow lagoons inside sand barrier beaches running parallel to the Gulf of Mexico. Yucatan lagoons contain both open water and mangrove swamps that are interspersed with stands of cattails and is a transition zone to upland savannas. These areas contain extensive beds of wigeon grass, shoalgrass, musk grass and turtle grass. Many have been degraded by natural events, mainly hurricanes that created permanent breaches of the barrier island. Human disturbances are characterized by seaports, settlements and roads crossing the coastal wetlands that increase the salinity gradient, which can kill the mangrove swamps, and reducing cover and food supplies to waterfowl.
Ducks Unlimited de Mexico (DUMAC) is currently classifying wetlands of the Yucatan Peninsula, which includes the states of Centla, Campeche, Yucatan and Quintana Roo. This information will be key support for the development of future conservation projects.
Importance to waterfowl
The Gulf Coast of Mexico supports 35.2% of the wintering waterfowl in Mexico (DUMAC 1990). The Laguna Madre, Tamaulipas accounts for 18.8% (including the Rio Grande), Tamiahua 3.6% (including Panuco and Tamesi Rivers), Albarado 2.5%, Tabasco 6.9% and Campeche and Yucatan 3.8% (DUMAC 1990).
Waterfowl surveys in 1994 recorded a total of 818,015 ducks and 16,795 geese along the main wintering areas in the Gulf Coast. Of the total ducks reported, 506,600 were dabblers and 311,505 divers. The most abundant species were blue-winged teal (295,785) and redheads 230,075. Between 1991 and 1997 the average number of waterfowl distributed along this area was 649,413 ducks, of which 358,263 were dabblers and 431,273 divers. An average of 23,323 geese was counted during the same period (USFWS 1994).
The Laguna Madre in Tamaulipas, by itself, is a key wintering habitat for 36% of the North American population of redhead. The Laguna Madre in Texas accounts for 41% of the redheads and the rest of the Gulf Coast held 23% during between 1980-94 (Woodin 1996). The Tabasco, Campeche and Yucatan Lagoons are key wintering habitats for the blue-winged teal, holding 44.8% of the waterfowl distributed along the Gulf Coast (USFWS 1997).
*Region 29 - NABCI Bird Conservation Regions 36 & 37 (Mexico only)