Mosquitia-Nicaraguan Caribbean Coast mangroves
Mangrove scene in Nicaragua. Photograph by Steve Cornelius
The Mosquitia-Nicaraguan Caribbean Coast mangrove ecoregion covers a large expanse of coastline beginning in Honduras at the delta of the Patuca River, continuing through Nicaragua to a point just south of the Bahía Punta Gorda. Some off-shore islands like Corn Island are also included in this ecoregion. Coastal areas generally consist of low-lying alluvial floodplains that range from sea level to 20 meters (m); covered with palm swamps and mixed rainforest, and numerous blackwater canals and creeks. In between are beaches that are important nesting areas for endangered sea turtles that feed in the sea grass beds and visit mangrove areas.
Mangroves are sparse in the southern part of this ecoregion, and are primarily found in estuarine lagoons and in patches in association with the freshwater palm species Raphia taedigera, and mixed with a high diversity of other species. In the Corn Islands for example, fifteen percent of the wetlands are dominated by Raphia taedigera and Rhizopora mangle. Mangrove densities increase in the northern part of the ecoregion. In addition to the association with the freshwater palms, these mangroves are part of a complex of diverse habitats that include humid broadleaf forest, pine forest, coastal wetlands and bamboo forests, as well as coral reefs and some of the most extensive seagrass beds in the world.
Location and General Description
The sparseness of mangroves in this ecoregion is attributable to the dominance of freshwater in this system. Numerous rivers discharge into the Caribbean Sea within this ecoregion including the Cruta, Coco, Likus, Wawa, Kukalaya, and Punta Gorda Rivers. There are also many lagoons along this coast some of them forming a complex system, such as those close together lying between the northern extent of the ecoregion and the Honduras/Nicaragua border. Annual rainfall ranges between over 5000 millimeters (mm) at the southern end, and approximately three millimeters (mm) in the northern areas. Peak rainfall occurs in the warmest months between May and September. A relatively dry season occurs from January to April, which coincides with stronger trade winds that blow steadily from the east-northeast and temper the tropical heat. Tides are semi-diurnal with an average range of less than half a meter. Poorly drained silt and clay soils promote the formation of channels; the depth of channels increases two to six meters in the summer, when the mouths of the Cuero and Salado Rivers close up.
In a number of places, such as on Corn Island, the direct connection to the ocean is blocked most of the year by sand dunes. These dunes are broken open when, after heavy rainfall, the wetlands are filled building hydrostatic pressure against the dunes allowing a temporary exchange between the wetlands and the offshore system.
The Atlantic coast in this area is relatively undeveloped. Population density is about six people per square kilometer (km2), except on the Corn Islands. Most of the country's population is found on the Pacific coast.
Biodiversity Features
This area of the Atlantic coast is part of a biological corridor that biogeographically links North and South America. The mangrove vegetation of this Caribbean Coast ecoregion tends to grow in even age stands. Also they are often relatively young and small in stature due to periodical disturbance by hurricanes, which may result in a die-off of all mangroves, as occurred in 1988 resulting from Hurricane Joan. However, they do regenerate. Mangrove species are diverse in this ecoregion with Red Mangrove (Rhizophora mangle), Black Mangrove (Avicennia germinans), White Mangrove (Laguncularia racemosa), Buttonwood (Conocarpus erectus), and another species denoted by the common name Red Mangrove (R. harrisonii). Occasional rare occurrences of Piñuelo Mangrove (Pelliciera rhizophorae) have been reported; however, most source list its distribution as not extending north of Costa Rica. Plant species associated with mangroves include the Leather Fern (Acrostichum spp.), which also invades cut over mangrove stands and provides some protection against erosion. In this particular ecoregion, the mangroves are associated with the freshwater palm speciesRaphia taedigera.
The offshore sea grass beds, which are the most extensive in the world, are a source of food and refuge for half of the world's, endangered green sea turtle population (Chelonia mydas). Mangroves play an important role in trapping sediments from land that are detrimental to the development of both coral reefs and the sea grasses that are associated with them.
In the Rio Platano Biosphere Reserve, mangroves are found on the fringe of coastal lagoons, where Rhizopora mangle and Langucularia racemosa are the most dominant species. Other plant species associated with mangroves here are sea grapes (Coccolaba uvifera) and coconut palms (Cocos nucifera). Inland from the coast is a savanna that is dominated by a subspecies of Caribbean pine (Pinus caribaea hondurensis) in the drier areas. In the moister areas, it consists of sedge prairie, which includes palm thickets of silver saw palmetto (Acoelorraphe wrightii). Other habitats found in different parts of the lowland areas are broadleaf gallery forests and swamp forests.
Avifauna of this ecoregion, as well as mammals, are not usually restricted to mangrove habitat but use the resources available in this ecoregion when needed. Migrants often rest or even spend the winter in this ecoregion. Migrations will also occur during times of drought or lowered resource availability in surrounding ecoregions. Birds more specific to mangrove communities are roseate spoonbill (Ajaja ajaja), white-fronted parrot (Amazona albifrons), blue winged teal (Anas discors), common black hawk (Buteogallus anthracinus), muscovy duck (Cairina moschata), boat-billed heron (Cochlearius cochlearius), and mangrove warbler (Dendroica petechia). Birds that may visit mangrove communities include Amazona autumnalis, scarlet macaw (Ara macao), green macaw (Ara ambigua), military macaw (A. militaris), snowy cotinga (Carpodectes nitidus), and several parrots, parakeets, and hummingbirds.
Mammals commonly found within the mangrove areas include pacas (Agouti paca), ocelots (Leopardus pardalis), Central American otters (Lutra longicaudis), jaguars (Panthera onca), Baird's tapirs (Tapirus bairdii), Caribbean manatees (Trichecus manatus), collared peccaries (Tayassu tajacu), black mantled howler monkeys (Alouatta palliata), Geoffrey's spider monkeys (Ateles geoffroyi), and white-faced capuchins (Cebus capucinus). Also found in mangrove habitat are reptiles such as American crocodile (Crocodylus acutus), brown caiman (Caiman crocodilus), green sea turtle (Chelonia mydas), leatherback turtle (Dermochelys coriacea), Eretmochelys imbricata, loggerhead turtle (Caretta caretta), iguana (Iguana iguana), ctenosaur (Ctenosaura similis), and snakes (Boa constrictor).
Current Status
Many of the mangroves on Corn Island where the population densities are highest have been degraded by sewage discharge. The current condition of the mangroves is mainly a result of natural processes of destruction and regeneration however some mangrove loss has resulted in the past.
Protected areas in this ecoregion that contain mangroves are all in Honduras and include the Rio Platano Biosphere Reserve, the Jeannette Kawas National Park, Barras de Cuero y Salado and Punta Izopo. The last three of these are considered wetlands of international importance under the RAMSAR convention.
Types and Severity of Threats
Upstream activities threaten mangroves due to alteration of hydrologic factors. Deforestation for timber extraction, mining, redirecting of surface water flow as a result of dam construction for hydroelectric development, land use change as a result of unplanned settlements and agricultural expansion including pesticide runoff, ranching and subsistence agriculture on steep slopes which leads to erosion are all such sources of change. Sedimentation is also causing problems for the reefs, together with discharges of wastes and chemical water pollutants.
The increase incidence of tropical storms and hurricanes is a continual threat to mangrove [[ecoregion]s]. In the Corn Islands, tropical storms occur on an average of once a year but in 1996, three tropical storms and one hurricane occurred. Hurricanes are expected once every fifty years but three have struck the Corn Islands in the past two decades. Although it is not possible to link these particular extreme events with climate change, an increase in their frequency is consistent with the effects of short term temperature vacillations, in that hurricanes have a tendency to occur in warmer waters.
Justification of Ecoregion Delineation
Classification and linework for all mangrove [[ecoregion]s] in Latin America and the Caribbean follow the results of a mangrove ecoregion workshop and subsequent report.
Further Reading
- Ecoregional Workshop: A Conservation Assessment of Mangrove Ecoregions of Latin America and the Caribbean. 1994. Washington D.C., World Wildlife Fund.
- Kjerfve, B., and D.J. Macintosh. 1997. The impact of climatic change on mangrove ecosystems. In B. Kjerfve, L.D. Lacerda, and E.H.S. Diop, editors, Mangrove ecosystem studies in Latin America and Africa. UNESCO, Paris, France.
- Olson, D.M., E. Dinerstein, G. Cintrón, and P. Iolster. 1996. A conservation assessment of mangrove ecosystems of Latin America and the Caribbean. Final report for The Ford Foundation. World Wildlife Fund, Washington, D.C.
- Roth, L.C. 1997. Implications of periodic hurricane disturbance for the sustainable management of caribbean mangroves. In B. Kjerfve, L.D. Lacerda, and E.H.S. Diop, editors, Mangrove ecosystem studies in Latin America and Africa. UNESCO, Paris France.
- Ryan, J.D., L.J. Miller, Y. Zapata, O. Downs, and R. Chan. 1998. Great Corn Island, Nicaragua. In B. Kjerfve, editor, Caribbean coral reef, seagrass and mangrove sites. UNESCO, Paris France.
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