The Bahamian mangroves (now classified as part of the larger Bahamian-Antillean magroves ecoregion) are found in a large area of shallow water that is of high importance for its ecological productivity. The mangroves are an important source of nutrients and provide shelter for many juvenile species of fish associated with this area, which also includes extensive coral reefs and seagrass beds. They also contain areas of high importance for large populations of resident and migratory waterfowl as well as many other species of avifauna.
Location and General Description
The Bahamian mangroves within the larger Bahamoan-Antillean magroves ecoregion consist of over 3000 low-lying islands and portions of the Americas mainland with a maximum elevation of 60 metres (m), only 29 of which are inhabited, and most of which are no more than rocky islets and cays. 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 millimeters (mm) in the north to 700 mm in the south. Tides are semi-diurnal, with a range of 1.5 m, 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. 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. 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. The seagrass Thalassia testudium is often found at low energy sites in association with mangroves. 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) is found.
The Inagua National Park in the Bahamas, an element of this ecoregion, 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.
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.
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); 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.
There are 425,870 hectares (ha) of saline wetlands that contain mangroves at numerous sites throughout the Bahamas. and other Caribbean shorelines. At least two and probably half of the 12 protected areas of the Bahamas contain mangroves.
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.
- For a terser summary of this entry, see the WWF WildWorld profile of this ecoregion
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