Location and General Description
The moist Pacific Coast ecoregion runs along the coastline of Central America from near the town of Jaco, Costa Rica to the southwestern corner of the Peninsula de Azuero, Panama. This ecoregion encompasses the Gulfo Dulce, the Gulfo de Chiriquí, and the Gulfo de Montijo. According to Spalding (1997) this ecoregion’s diversity results from its coverage of areas lying south of the Gulfo de Nicoya which represent a transition zone, of movement from dry to moist with a much shorter dry season (only Jan-March) and more precipitation in the wet season. Many of the streams and rivers, which help create this mangrove ecoregion, flow down from the Talamanca Mountain Range. Because of the resulting high mountain sediment loading, coral reefs are sparse along the pacific coast of Central America, and those that exist are mostly found offshore near islands. In this region, coral reefs are associated with the mangroves at the Isla del Caño Biological Reserve, 17 km from the shore near the Térraba-Sierpe Mangrove Reserve (Polanía 1993). The Térraba-Sierpe, found at the mouths of the Térraba and Sierpe rivers, is considered a wetland of international importance (Ramsar 1999).
In this ecoregion annual rainfall is higher than in the northern parts of Central America at >2000 mm, reaching up to 3,647 mm at the southern end. The dry season is also shorter averaging < 3 months, resulting in better developed mangroves (Polanía 1993). Between May and December rainfall is influenced by the Intertropical Convergence Zone (ITCZ), an area of low atmospheric pressure where winds from the northern and southern hemispheres converge. These rains cover the ecoregion, and are considered the rainy season. The dry season occurs from January to April when the colder winds from the north push the ITCZ southward and bring about the upwelling of colder, nutrient rich waters from below the surface. Small wetlands also function as reserves, slowly releasing water during the dry season. Fine sediment dominates most sites but sandy areas are also found (Jimenez 1999).
Because of high moisture availability, the salinity gradient is more moderate than in the more northern ecoregion such as the Southern dry Pacific Coast ecoregion. Resulting mangrove vegetation is mixed with that of marshland species like Pterocarpus officinalis, Campnosperma panamensis, Bactris minor, and is adjacent to "yolillo" palm (Raphia taedigera) swamp forest, which provides shelter for Odocoileus virginianus and Frazier monkeys. Mangrove tree and shrub species include Rhizopora mangle, R. harrisonii, R. racemosa [up to 45 m high], Avicennia germinans, A. bicolor, A. tonduzii, Laguncularia racemosa, Pelliciera rhizophorae (Polanía 1993). According to Chapman (1992) Avicennia germinans only occurs in this Costa Rican and Panamanian ecoregion stretching slightly into northwestern Columbia. Dominant species change slightly in southern more humid part of Costa Rica where Pelliciera rhizoporae and Rhizopora racemosa grow (Polanía 1993). Some vegetation, which grows in association with mangrove trees, is the fern Acrostichum aureum and Tabebuia palustris.
The mangrove ecosystems of this ecoregion serve as wildlife refuges, nursery and spawning areas, wildlife habitat, nutrient and sediment retention areas and shoreline protection (Olson et al. 1996). These features build upon each other to attract many different species of wildlife to the ecoregion for the purpose of attaining important resources such as food and shelter.
Two endemic birds listed by IUCN as vulnerable are found in the mangroves of this ecoregion: the mangrove hummingbird (Amazilia boucardi) and the yellow-billed cotinga (Carpodectes antoniae) (Stattersfield et al.1998). The favorite flower of the mangrove hummingbird is that of the Pelliciera rhizophorae, making it the only mangrove species which is pollinated by a vertebrate (Jimenez 1999). Other birds most specific to mangroves include roseate spoonbill (Ajaia ajaja), gray-necked wood rail (Aramides cajanea), rufous-necked wood rail (A. axillaris), mangrove black-hawk (Buteogallus subtilis), green-backed heron (Butorides striatus), Muscovy duck (Cairina moschata), boat-billed heron (Cochlearius cochlearius), white ibis (Eudocimus albus), Amazon kingfisher (Chloroceryle amazona), mangrove cuckoo (Coccyzus minor), mangrove warbler (Dendroica petechia) and black-necked stilt (Himantopus mexicanus) just to name a few.
Mammals although not as numerous as birds, include species such as paca (Agouti paca), mantled howler monkey (Allouatta palliata), white-throated capuchin (Cebus capucinus), pygmy anteater (Cyclopes didactylus), Central American otter (Lutra annectens), white-tailed deer (Odocoileus virginianus) [feeds on leaves in A. bicolor and L. racemosa forests], northern raccoon (Procyon lotor), crab-eating raccoon (P. cancrivorus) [can be found both on the ground and in the canopy consuming crabs and mollusks], Mexican anteater (Tamandua mexicana). Reptiles including the Basilisk lizard (Basiliscus basiliscus), snake (Boa constrictor), American crocodile (Crocodilus acutus), spectacled caiman (Caiman crocodilus), Ctenosaur (Ctenosaura similis) and green iguana (Iguana Iguan) do well in the mangroves. Reptiles can live on fruits, invertebrates, birds, small mammals and other reptiles [species lists from: Jimenez 1999; Ramsar 1999; Polonía 1993; D'Croz 1993; Reid 1997; Stiles and Skutch 1989).
According to Stattersfield (1998) the widespread and extensive destruction of forests in the defined EBA includes major stands of mangroves. This destruction of mangrove ecosystems has caused a decline in available habitat and the resulting decline in species numbers Sites with the greatest remaining concentrations of mangroves: Térraba-Sierpe (17,737); Estero Damas Palo Seco (2,312 ha); Coto Colorado (875 ha) (Polanía 1993).
A large area is protected in Costa Rica as Corcovado National Park on the Osa Peninsula (Davis 1997). This park is also the largest tract of protected land on the Pacific side of Central America (Davis 1998).
Types and Severity of Threats
In general, the river basins are of high relief (i.e., have steep slopes), have seasonally intense rainfall, and highly erodable soils, which makes them prone to erosion caused by agricultural practices, deforestation, and livestock grazing. The direct result of which is high sedimentation, which also brings nutrients that are found in higher concentrations during the rainy season (Jimenez 1999). Pressures to convert mangroves to agricultural uses even though mangrove soils are too poor with drainage problems and high salinity and acidity preventing the profitable growth of crops. Agricultural farming is also a threat due to the use of agrochemicals such as fertilizers and pesticides which runoff into the mangrove ecosystems. Lands converted to agriculture are often subsequently abandoned because of high maintenance costs and erosion begins (Polanía 1993). Another threat is urban encroachment, particularly around Puntarenas and Quepos, which were built in mangrove areas to begin with. Unregulated mangrove cutting for bark and uncontrolled harvesting of the clam "piangua" Anadara tuberculosa have been a threat at least in the past but the government has established quotas and extraction methods, and is preparing a management plan (Ramsar 1999). Bark collectors have had a large impact on the Terraba range because they felled only the largest and most vigorous Rhizopora trees, which also created significant gaps in the canopy. Charcoal production in the Térraba-Sierpe mangrove reserve accounted for 1911 m3 of felled wood in 1987 (Polanía 1993). Other threats according to Spalding (1997) include exploitation of mangroves for tannin, fuelwood, timber and charcoal as well as oil spills such as the one in 1986 and urban development.
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 (1994) and subsequent report (Olson et al. 1996).
Chapman, V. J., editor. 1992. Ecosystems of the World; Wet Coastal Ecosystems. Elsevier Science Publishers B. V., Amsterdam, Netherlands.
Davis, S.D., V.H. Heywood, O. Herrera-Mcbryde, J. Villa-Lobos and A.C. Hamilton. 1997. Centres of Plant Diversity: Volume 3 The Americas. Information Press, Oxford, UK.
Ecoregional Workshop: A Conservation Assessment of Mangrove Ecoregions of Latin America and the Caribbean. 1994. Washington D.C., World Wildlife Fund.
Jimenez, Jorge A. 1999. Ambiente, distribucíon y características estructurales en los manglares del Pacífico de Centro América: contrastes climáticos. In: Yáñez-Arancibia, Alejandro and Ana Laura Lara-Domínguez , editors. Ecosistemas de Manglar en América Tropical. Instituto de Ecologia, A.C. Xalapa, México; UICN/ORMA Costa Rica; NOAA/NMFS Silver Spring MD USA.
Olson, David M., Eric Dinerstein, Gilberto Cintrón and Pia Iolster. 1996. A Conservation Assessment of Latin America and the Caribbean: Report from WWF's Conservation Assessment of Mangrove Ecosystems of Latin America and the Caribbean Workshop. WWF, Washington D.C.
Polanía J. 1993. Mangroves of Costa Rica. L.D. Lacerda, editor. Conservation and sustainable utilization of Mangrove Forests in Latin America and Africa Regions. Part 1; Volume 2:
Ramsar, 1999. A Directory of Wetlands of International Importance designated under the Convention on Wetlands of International Importance Especially as Waterfowl Habitat (Ramsar, 1971). Scott Frazier ed. Compiled by Wetlands International for the Seventh Meeting of the Conference of Contracting Parties to the Ramsar Convention San José, Costa Rica, May 1999. http://www.wetlands.agro.nl/ramsar_database/HTML_DIR/Intro/Introduction.htm
Reid F. A. 1997. A field guide to the mammals of Central America and Southeast Mexico. Oxford University Press, New York
Stiles F.G. and A.F. Skutch. 1989. A Guide to the Birds of Costa Rica. Comstock Publishing Associates, Cornell University Press, Ithaca NY.
Stattersfield, A.J., M.J. Crosby, A.J. Long, and D.C. Wege, 1998. Endemic bird areas of the World, priorities for biodiversity conservation. Birdlife Conservation Series No.7. BirdLife International, Cambridge, UK.
Spalding, Mark, Francois Blasco and Colin Field., editors. 1997. World Mangrove Atlas. Chapter 7: The Americas: Costa Rica and Panama. The International Society for Mangrove Ecosystems, Okinawa, Japan.
Prepared by: Sylivia Tognetti and Christine Burdette
Reviewed by: In process