Location and General Description
Lake Enriquillo in the southwestern section of the Dominican Republic is located at 18º30’N and 71º40’W, occupying the lowest part of the basin known as Hoya del Lago Enriquillo between the Neyba and Bahoruco ranges, and has geomorphological characteristics that are unique in the Caribbean region. It is the largest lake in the Caribbean; it is 35 meters long and 12 meters wide and has a maximum depth of 24 m. There are three islands on the lake: Cabritos Island, Islita and Barbarita Island. The first is the largest island and is 12 km long and an average of 2 km wide. Water temperature in the lake varies from 23.9 to 29ºC, salinity is twice that of the sea and its waters are sulfurous (Amezqueta et al. 1987). Rocks in the zone are coral limestones and remains of mollusk shell because in past geological eras the ecoregion corresponded to the marine channel that divided the island of Hispaniola into two paleoislands. Annual precipitation in this ecoregion is between 400 and 500 mm, representing one of the most arid areas on the island. The lake is fed by subterranean and surface influents, but its volume only increases significantly with the hurricanes, cyclones and tropical storms that lash the island. In the Dominican Republic, other less important lakes with origins similar to those of Lake Enriquillo are Rincón Lagoon (Cristóbal or Cabral), Lake Caballero. Rincón Lagoon is 47 km2 and is the largest body of fresh water in the Dominican Republic. In Haiti, Saumatre Lagood (Étang Saumatre or Lago Azuei) is the country’s largest lake. It occupies another concavity 10 km west of Lake Enriquillo, separated from it by the Jimaní anticline. It covers an area of approximately 120 km2 and is located in the far east of the Cul-de-sac Valley. Another smaller lake on the Haitian coast and close to Saumatre is Trou Cayman, measuring approximately 15 km2 (Octave 1999).
The shores of Lake Enriquillo, as well as the three islands on the lake and the smaller lagoons, have dry subtropical forest and subtropical thorny mountain that is very valuable because it has species with very restricted distributions. Vegetation consists primarily of bayahonda (Prosopis juliflora), cambrón (Acacia macracantha), guayacán (Guaiacum officinale), almácigo (Bursera simarouba), baitoa (Phyllostylon brasiliensis) and spiny hrubs (cactáceas) such as the guazábara (Cylindropuntia caribaea), cayucos (Pilosocereus polygonus), melón espinoso (Melocactus lemairei), alpargata (Opuntia moniliformes) and bombillito (Neomammillaria prolifera) . Common palm threes are the yarey (Copernicia berteroana) and the palma cacheo (Pseudophoenix vinifera). In the wetter areas the baría (Callophylum calaba), copey (Clusia rosea), mangle rojo (Rhizophora mangle) and mangle botón (Conocarpus erecta) predominate (Olfield 1997; Narpier n.d.).
An inventory of the flora on Cabritos Island shows that there are 105 species of plants, primarily herbaceous (57 species), followed by trees, cactus, shrubs and creepers. To be noted is the limited numbers of palm and epiphyte species. More than 10% of the species on Cabritos Island are endemic to Hispaniola or the ecoregion (Marcano 1987). This habitat of subtropical dry forest and subtropical thorny montane vegetation is of great interest due to the abundance of xerophytic vegetation on the island of Hispaniola (Olfield 1997).
Both land and aquatic fauna in this ecoregion are also of great biological value. In the wetter areas, we find amphibians like the "maco pempém" (Bufo marinus) and endemic "bufónido" (Pelthophryne guntheri). In drier areas, we find various reptiles, with two species of iguana (Cyclura spp.), 25 species of lizards (Anolis spp., Ameiva spp., Aristelliger cochranae, and others) and 13 species of snakes (Epicrates spp., Uromacer catesbyi, and others). Of the two iguana species, Cyclura ricordi is critically at risk of extinction and lives only in this lake, in the Jaragua National Park. Also to be noted is the largest snake on Hispaniola Island is the Alsophis anomalus, which is only found in two other areas with insular geography. Aquatic herpetofauna is represented by the American crocodile (Crocodylus acutus) and a turtle the Hispaniolan slider or "jicotea" (Trachemys decorata) endemic to the island; with its largest population in Lake Rincón. Current populations of American crocodile on the island of Hispaniola are only found on Lake Enriquillo, Manzanillo Bay and Lake Saumatre (Haiti) and Lake Enriquillo has the largest natural population in the world (estimated population of 400) (Amezqueta et al. 1987). Aquatic fauna is also represented by tilapia and other fish.
Of the 35 species of land birds reported, the most representative are the broad-billed tody (Tordus subulatos), burrowing owl, "cucú" (Athene cunicularia), palm crow, "cao" (Corvus palmarum) and vervain hummingbird (Mellisuga minima). Of the 62 species of aquatic birds, many of them migratory, we mention the pink flamingoes (Phoenicopterus ruber) , roseate spoonbill (Ajaia ajaja), green-backed heron (Butorides striatus), little blue heron (Egretta caerulea), tricoloured heron (Hydranassa tricolor) and Bahama pintail (Anas bahamensis) (Marcano n.d.). Land mammals are represented by the greater bulldog bat (Noctilio leporinus) and Mexican free-tailed bat (Tadarida brasiliensis). It is important to emphase the presence of sea cows or manatees (Trichechus manatus) in Lake Saumatre (Octave 1999).
Hurricanes and tropical storms can be beneficial to the lakes because they replenish them with freshwater (Marcano 1987).
According to Dinerstein et al. 1995, this ecoregion is outstanding in regional terms, with a vulnerable conservation status and maximum conservation priority (I). According to Olson et al. 1996, there is sufficient taxonomic and geographic data on the ecoregion to implement an appropriate conservation strategy. The succulent vegetation endemic to this area is very vulnerable to human activities and is thus a plant community at risk (Oldfield 1997).
There are three National Parks in the ecoregion with IUCN management category II, all of them on the Dominican Coast. In 1974, the Cabritos Island National Park was created with an area of 26 km2. In 1995, the Enriquillo Lake National Park was created with 320 km2, and in 1997 Rincón Lagoon’s category was changed from Wildlife Refuge to National Park, increasing the protected area of the park to 240 km2.
Types and Severity of Threats
One of the most significant threats to Lake Enriquillo is its high salinity at certain times of year as a result of the diverting of freshwater by pipes emptying into the lake for use in the area’s agriculture. Another threat, particularly to crocodiles, is indiscriminate hunting as well as altered habitat due to reduced vegetation. Also detrimental is the drilling of tubular wells in communities close to the lake, grazing of livestock and gathering of firewood (Dinerstein et al. 1995). The most pressing causes of the degradation of Lake Saumatre and its surroudings involve the inflow of human and animal waste, sediments coming from mountain rains, contamination from detergents and other chemicals and the burning of trees (Octave 1999). Insular ecosystems are very fragile and once altered it is difficult for them to revert to their original state.
Justification of Ecoregion Delineation
Amezqueta, J., J.P. Pujas, L.E. Pérez, J. Alarcón, L. Valdez, and E. Bautista, 1987. Aspectos generales sobre el cocodrilo americano. Santo Domingo, República Dominicana.
Caribbean Environmental Programme (CEP) 1996. Status of Protected Area Systems in the Wider Caribbean Region. CEP Technical Report No. 36
Dinerstein, E., D.M. Olson, D.L. Graham., A.L. Webster, S.A. Primm, M.P. Bookbinder, and G. Ledec. 1995. A Conservation Assessment of the Terrestrial Ecoregions of Latin America and the Caribbean.The World Bank.
DNP 1989. Los parques nacionales de la República Dominicana. Dirección Nacional de Parques, Santo Domingo, RD.
Hartshorn, G., G. Antonini, and R. DuBois. 1981. La República Dominicana. Pefil ambiental del país. Un estudio de Campo. JRB Associates, Virginia, USA.
Hernández, C. y J. Czerwenka, 1986. Contribuciones para un nuevo concepto de conservación en el área del Lago Enriquillo. Secretaría de Estado de Agricultura, Departamento de Vida Silvestre. Santo Domingo, R.D.
IUCN, 1982. IUCN directory of Neotropical Protected Areas.
Marcano, E. J., 1987. Flórula de la Isla Cabritos. http://naturalista.virtualave.net/estudios/flórula.html
Marcano, J. (n.d). Suroeste Dominicano. http://www.spaceports.com/~jmarcano/suroeste/areas/areas.html
Moreta, A. n.d. El lago Enriquillo aumenta su caudal con el agua de los ciclones y tormentas tropicales que azotan el país. El Siglo. http://www.elsiglo.net/reporte/enriquillo.htm
Narpier, R. n.d.. Flora, fauna y belleza del Lago Enriquillo. El Siglo. http://www.elsiglo.net/reporte/enriquillo.htm
OAS. 1984. Écologie, Republique d'Haiti. Map 1:500,000. Organization of American States, Washington, D.C., USA
Octave, F. 1999. Lake Azuei: An important resource in Haiti being wasted. Island beat: News from the Environmental Frontline of the Caribbean. http://www.panosinst.org/Island/IB1e.htm
Oldfield, S. (comp.), 1997. Cactus and Suculent Plants. IUCN/SCC Cacuts and Succulent Specialist Group. Gland, Switzerland.
Olson, D., E. Dinerstein, G. Castro, and E. Maravi. 1996. Identifying gaps in botanical infromation for biodiversity conservation in Latin America and the Caribbean. World Wildlife Fund, Washington, D.C., USA.
SEA/DVS 1990. La diversidad biológica en la República Dominicana. Reporte preparado por el Departamento de Vida Silvestre para el Servicio de Cooperación Social-Técnica y WWF-US. Secretaría de Estado de Agricultura, SURENA/DVS, Santo Domingo, RD.
SEA/DVS 1995. Mejoramiento de la Situación Ambiental en la Propuesta Reserva de Biosfera "Enriquillo", Tomo 2. Santo Domingo, R.D.
Tasaico, H. 1967. Mapa ecologico de la Republica Dominicana. Unidad de Recursos Naturales de la Union Panamericana.
UNEP-WCMC. Protected Areas Programme. http://www.unep-wcmc.org/cgi-bin/padb.p
Valdez, G. y M. Mateo. 1992. Sistema de áreas protegidas de la República Dominicana. Dirección Nacional de Parques, Santo Domingo, RD.
Prepared by: Ugo D'Ambrosio
Reviewed by: In process