Location and General Description
The Bahamas islands ecoregion consist of over 3000 low-lying islands with a maximum elevation of 60 m, only 29 of which are inhabited, and most of which are no more than rocky islets and cays (Bacon 1993). They are found in an extensive area of shallow water due to a base of large submerged limestone banks surrounded by deep channels. They are also situated between two warm currents – the Gulf Stream which is constant, and the Antilles current that comes across the Atlantic and shifts its location between the northern and southern part of the Bahamas islands in summer and winter. This creates a north to south variation in water temperatures with cold periods sufficient to reduce species diversity and coral reef development. The climate is sub-tropical, with a range of temperatures, north to south, between mean maximums of 27 and 29°C, and mean minimums of 20 and 25°C. Precipitation decreases from 1400 mm in the north to 700 mm in the south. Tides are semi-diurnal, with a range of 1.5m, and salinity is for the most part constant. These islands are also among those most exposed to hurricanes in the Caribbean region because they are along a frequent path of hurricanes originating in the Atlantic (Buchan 2000). In addition to having relatively low precipitation, there are no major rivers because of the porous limestone substrate, through which water rapidly enters underground areas.
Low freshwater inputs, in addition to the stresses of exposure to low temperatures and frequent hurricane disturbances, the mangroves consist mostly of fringe and coastal scrub, with an average height of 4 m (Gerace 1998). Other signs of stress are small leaves and albinism among the seedlings of Rhizopora. They are found in sheltered bays, marshes, lagoons, and tidal mudflats, where they play an important role in shoreline stabilization, by trapping sediments and building up land areas (Gerace 1998; Buchan 2000). The seagrass Thalassia testudium is often found at low energy sites in association with mangroves (Buchan 2000; Gerace 1998). These mangroves still can be found on a gradient with species that have a freshwater preference closer or further inland such as the white mangrove (Laguncularia racemosa) and the buttonwood mangrove (Conocarpus erectus) progressing to red mangrove Rhizopora mangle). Closest to the sea or at the waters edge of inland lakes with high salinity the black mangrove (Avicennia germinans).
The Inagua National Park in the Bahamas is a wetland of international importance, which contains dense swamps of Avicennia germinans and Conocarpus erectus. These mangroves are also an important component in a mosaic of diverse habitats that include seasonal marshes, swamps, pools and open water. This area is important to the endemic turtle, Chrysemys malonei, and an endemic subspecies of the threatened parrot Amazona leucocephala bahamensis. It also supports a breeding colony of the flamingo Phoenicopterus ruber (Frazier 1999).
The coastal mangroves, together with coral reefs and seagrass beds, form a highly diverse and structurally complex ecosystem in which the reefs act as a barrier that shelters seagrass beds and mangroves from high wave energy and strong coastal currents typical of the Caribbean environment. Mangroves and seagrass beds in turn provide foraging and nursery habitats for many reef species and sea turtles that are found throughout the Bahamas.
Birdlife International (Stattersfield et al. 1998) considers the Bahamas islands an endemic bird area. There are at least four bird species endemic to the Bahamas islands which may utilize mangrove habitats at times including the Bahama woodstar (Calliphlox eveltnae), white-cheeked pintail (Anas bahamensis), Bahamas swallow (Tachycinetacyaneoviridis) and Bahama yellowthroat (Geothlypis rostrata) (Stattersfield et al. 1998); although none of them specifically live in mangrove habitat exclusively. Other bird species associated with mangroves include spotted sandpiper (Actitis macularia), roseate spoonbill (Ajaia ajaja), green heron (Butorides virescens), belted kingfisher (Ceryle alcyon), mangrove cuckoo (Coccyzus minor), mangrove warbler (Dendroica petechia), and reddish egret (E. rufescens).
Sea turtles found throughout Bahamas islands utilizing mangrove habitats include the green turtle (Chelonia Mydas), hawksbill (Eretmochelys imbricata), loggerhead (Caretta caretta), and leatherback (Dermochelys coriacea). Important fish species found in Bahamian mangroves are snappers (Lutjanus spp.), grunts (Haemulon spp), parrotfishes (Scarus spp and Sparisoma), and mojarra (Gerres spp. and Eucinostomus spp), Nassau grouper (Epinephelus striatus), bonefish (Albula vulpes), tarpon (Megalops atlanticus) and barracuda (Sphyraena barracuda) a very important economically as a sport fishery. Species lists compiled from Buchan 2000; Frazier 1999; Raffaele et al. 1998.
There are 425,870 ha of saline wetlands that contain mangroves at 20 sites throughout the Bahamas (Bacon 1993). At least two and probably half of the 12 protected areas of the Bahamas contain mangroves (BEST 1998a).
Types and Severity of Threats
The most obvious concern is clearing of mangrove areas for development of resorts, marinas and residential areas, and also for purposes of mosquito control and generally, for access to waterfront. There is also an increasing concern with climate change, because of the implications of sea-level rise for a low-lying area, and also because it is associated with increases in hurricane activity (BEST 1998b).
Justification of Ecoregion Delineation
lassification 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).
Bacon P.R. 1993. Mangroves in the Lesser Antilles, Jamaica and Trinidad and Tobago. L.D. Lacerda, editor. Conservation and sustainable utilization of mangrove forests in Latin America and Africa Regions. Part I: Latin America. International Society for Mangrove Ecosystems and the International Tropical Timber Organization.
BEST 1998a. Commonwealth of the Bahamas Draft National Report to the Conference of the Parties to the Convention on Biological Diversity. The Bahamas Environment Science and Technology Commission (BEST) www.biodiv.org/doc/meetings/cop/cop-05/information/cop-05-inf-24-en.pdf.
BEST 1998b. The Bahamas National Climate Change Workshop. The Bahamas Environment Science and Technology Commission (BEST) National Climate Change Committee (NCCC). July 30-31 1998, Nassau, The Bahamas. http://www.best.bs/activity/agenda.html
Bucchan, K.C. 2000. The Bahamas. C. Sheppard, editor. Seas at the millennium: An environmental evaluation. Elsevier Science Ltd. Oxford.
Ecoregional Workshop: A Conservation Assessment of Mangrove Ecoregions of Latin America and the Caribbean. 1994. Washington D.C., World Wildlife Fund.
Frazier, Scott. 1999., editor. A directory of wetlands of international importance designated under the Convention on Wetlands of International Importance (Ramsar, 1971). 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/ramsar_quick.html
Gerace, D.T., G.K. Ostrander, and G.W. Smith. 1998. San Salvador, Bahamas. B. Kjerfve, editor. CARICOMP – Caribbean coral reef, seagrass and mangrove sites. Coastal region and small island papers 3, UNESCO, Paris, xiv + 347 pp. http://www.unesco.org/csi/pub/papers/gerace.htm
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.
Raffaele, H., J. Wiley, O. Garrido, A. Keith, and J. Raffaele J. 1998. A guide to the birds of the West Indies. Princeton University Press, Princeton New Jersey.
Rathcke, B, C. Landry and L.B. Kass. White Mangroves: Are males necessary? Proceedings of the 8th symposium on the natural history of the Bahamas, 1999, in press.
Rathcke, B. L.B. Kass and N. Elliott. The pollinators of black mangroves and white mangroves on San Salvador Island. Proceedings of the 8th symposium on the natural history of the Bahamas, 1999, in press.
Spalding, M.D., F. Blasco, and C.D. Field, editors. 1997. World mangrove atlas. The International Society for Mangrove Ecosystems, Okinawa, Japan.
Prepared by: Sylivia Tognetti and Christine Burdette
Reviewed by: In process