The Petenes mangroves ecoregion stretches along the far northwestern coastal fringe of the Yucatan Peninsula, which sticks out into the Gulf of Mexico. The low annual rainfall in this ecoregion combined with the severe aridiity of the entire region has eliminated any significant rivers from the landscape. Therefore, the freshwater necessary for productive mangrove ecosystems derives from freshwater springs. Also of interest within this ecoregion, CONABIO has identified a terrestrial priority area which shares its territory with this ecoregion, Petenen-Ría Celestum. At least five Important Bird Areas also lie within this ecoregion; Los Petenes, Ría Celestún, Ichka' Ansijo, Reserva Estatal de Dzilám, and portions of Ría Lagartos.
Location and General Description
Petenes mangroves are located in Mexico at the border between the states of Yucatán and Campeche, in the western portion of the Yucatan Peninsula. The area is continuously flooded, though rivers are absent from the ecoregion. Instead, springs form in the bottom of the mangroves, providing freshwater and enormous quantities of nutrients; helping to regulate salinity and elevate nutrient concentrations. This coastal ecoregion lies in the part of the Yucatan Peninsula that receives the lowest annual rainfall averaging 450 millimeters (mm).
The Celestún Lagoon is the most important hydrologic feature within this ecoregion; it lies on a carstic platform, and can thus achieve a high salt content. The soils, derived from sedimentary rocks, are shallow in some areas, but deep in others. Different types of mangroves can occur, depending on the levels of salinity and the amount of nutrients present. The pygmy mangrove habitat is composed of short trees (less than five meters), while the fringe mangrove habitat is richer and composed of taller trees (15 to 20 meters). Both types of mangroves house the same tree species: Rhizophora mangle, Laguncularia racemosa and a few individuals of Avicennia germinans, which are scarce because they are relatively intolerant of high salinity and persistent floods. Jamaica Sawgrass (Cladium jamaicensis), Turtleweed (Batis maritima), Dwarf Glasswort (Salicornia bigelovii), and Typha dominguensis can also be found in association with the dominant species. A unique mangrove association, called Peten mangrove, is formed near the Celestún Lagoon. It is composed of the dominant species inhabiting mangroves, plus plants forming irregular hummocks of moist forests within the mangroves. Dominant species in petenes (other than mangrove trees) are: Manilkara zapota, Bursera simaruba, Malvaviscus arboreus, and Ficus tecolutlensis.
The Petenes mangroves constitute one of the two refuges for the endangered American flamingo (Phoenicopterus ruber). Many fish species use the mangroves as oviposition areas, as well as breeding grounds, contributing to the high diversity of ichthyofauna in this region. Some of the 107 fish species present use mangrove tree roots as natural refuges during the day, and feed on these root structures by night. Considering that many other species of vertebrates also depend on fish for food, this close relationship between the ichthyofauna and the mangroves is crucial to the maintenance of diversity in these communities. The Petenes also constitute a natural refuge for crocodiles, and the only dry refuge within the wetlands for deer, small monkeys, and rodents that use the mangroves as foraging grounds.
The great diversity of aquatic plants in this ecoregion led Lot & Novelo to consider this area the most diverse reservoir of aquatic plants in Mesoamerica. There are 304 species of birds, 33 species of mammal, and five species of reptile in the Petenes mangroves. Many birds are endemic and/or restricted-range species, adding to the ecological and biological value of Mexico's wetlands. Stattersfield et al. identifies two birds with limited ranges that include this ecoregion; the near endemic Mexican Sheartail (Doricha eliza) and the endemic Yucatan Wren (Campylorhynchus yucatanicus). Other birds that utilize this ecoregion are the Yellow-crowned Night-heron (Nyctanassa violacea), Neotropic Cormorant (Phalacrocorax brasilianus), Yellow-lored Amazon (Amazona xantholora), Yucatán bobwhite (Colinus nigrogularis), and zenaida dove (Zenaida aurita).
Many species use the mangroves of this ecoregion as their winter destinations including black-throated green warbler (Dendroica virens), Nashville warbler (Vermivora ruficapilla), cliff swallow, (Hirundo pyrrhonota), ruby-throated hummingbirds (Archilochus colubris), and ruddy turnstone (Arenaria interpres). In general, many mammals utilize mangrove areas especially in dry regions such as this part of the Yucatan Peninsula where this mangrove ecoregion is completely surrounded by dry forest. Central American mammals found in this ecoregion include Geoffroy's Spider Monkey (Ateles geoffroyi), Mexican mouse opossum (Marmosa mexicana), blackish small-eared shrew (Cryptotis nigrescens), and Yucatan deer mouse (Peromyscus yucatanicus).
Water pollution has degraded a significant portion of the mangroves in the Yucatán Peninsula. However, CONABIO & INE classify this as one of the largest areas where mangroves are in good state of conservation. The Biosphere Reserve of Ría Celestún protects 25% of the territory occupied by the Petenes wetlands; in addition, the North American Wetlands Conservation Council has designated this region as one of the priority wetlands of North America.
Types and Severity of Threats
Irregular human settlements, road openings for tourism and industrial activities, coconut palm cultivation and wildlife extraction threaten the mangroves in this ecoregion. Road openings alter and block the natural exchange of between salty and freshwater environments, interrupting the supply of nutrients crucial to mangrove survival. Native villagers maintain an illegal trade of exotic species as a source of income: palm trees and turtle eggs are the favored items, and can reach very high prices on the tourist market. This is especially detrimental to the area, because the coastal environments serve as nesting sites for many endangered turtles and crocodiles.
Justification of Ecoregion Delineation
Classification and linework for all mangrove ecoregions in Latin America and the Caribbean follow the results of a mangrove ecoregion workshop and subsequent report.
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