Tuesday, June 10, 2008

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Saloum River Estuary

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The coastal wetlands of Senegal are centered on the Saloum River and a myriad of estuaries and tidal flats that make up this complex ecosystem. The estuaries are generally bordered by dense, vigorous stands of mangroves. A major portion of this ecosystem enjoys full protection as the Saloum Islands National Park. The wetlands are critical habitats for wintering Palearctic birds, as well as many species of fish and mollusks. The mangrove vegetation is made up of several species, some of which form low canopies and others of the Rhizophora genus are among the tallest in the world, attaining heights of up to 40 meters. They grow in habitats that are periodically flooded by sea water (tidal influence) and river water. They are halophytes, plants which grow in salty environments.

Since the late 1960s, it has become apparent that many of the Saloum River mangrove forests are dying. One theory is that there is a serious mangrove disease which is systematically wiping them out. However, most evidence indicates that the mangrove die-off is related to the widespread Sahelian drought, which has plagued the region since 1968. The lack of rainfall has led to an accumulation of salts, exceeding the tolerance levels of the mangroves. The die-off is particularly acute in the northern half of the Saloum River wetland complex.

The dark green tones on the satellite imagery indicate mangrove forests in both the ‘before’ and ‘after’ images of the wetland complex around the Saloum River in Senegal. In the 5th November 1972 image the dark green coloration is more homogeneous in the area around the river delta and to the north of the river bank. In contrast, there is a patchy pattern of dark green in the same area within the river delta. And further more, there is an absence of the green coloration to the north of the river bank, the dark green being replaced by dark gray patches. This signifies a loss of the mangrove forest vegetation around the Saloum River.

Today, there are vast areas of standing dead mangrove carcasses; many of these areas have been reduced to barren mud flats. Only in the southern reaches of the wetland complex does one still see healthy stands of mangrove forests. Conservation efforts are under way through organizations such as the West African Association for Marine Environment (WAAME) which performs integrated and community-based management activities in the mangrove ecosystems in the Saloum Delta Biosphere Reserve, funded by the European Commission. View detail ed information

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