Bight of Sofala/Swamp Coast
Marine ecoregion in Mozambique
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Through Tide and River delta
Geography
The Bight of Sofala, also known as Sofala Bay, is a large indentation on the African coast. The continental shelf is wide in the region, reaching up to 140 km near Beira, in contrast with the narrower continental shelves to the north and south. The concave coastline and shallow seas create high-amplitude tides.
The Mozambique Current runs generally southward along the coast, and eddy currents form in coastal indentations like the Sofala Bight.
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Habitat types
24 rivers empty into the ocean in this region, which supports extensive mangroves, coastal swamps, and tidal estuaries. The Zambezi, Pungwe, and Save rivers form large river deltas, and numerous smaller rivers support coastal estuaries, mangroves, and estuaries. The waters are turbid with fine river sediments. The salinity of coastal waters varies seasonally as river discharge rises and falls, from 20 ppt in the rainy season to 34 ppt in the dry season.
Fauna
The extensive mangrove forests and coastal wetlands are important habitat for waterbirds, with over 73 species present.
The turbid waters of the region, along with occasional cold-water upwelling, limits the growth of corals in the region.
Human use
The Sofala Bank is a productive fishery, particularly for Indian prawns (Fenneropenaeus indicus).
Large dams on the Zambezi – Kariba Dam, completed in 1959, and Cahora Bassa, completed in 1975 – have altered freshwater, sediment, and nutrient flows into the Zambezi Delta and Sofala Bight. Large seasonal floods have been reduced, and sediments and nutrients formerly carried to the sea by floodwaters are now trapped behind dams.
The productivity of the Sofala Bight prawn harvest decreased continually from the 1970s through the 1990s, from 90kg per hour in 1977 to 30kg per hour by the early 2000s. The productivity continued to decrease from 2000 to 2014, and the region also saw a decline the total harvest of prawns and other food fish during the same period.
Protected areas
Marine protected areas include:
- Marromeu National Reserve and other game reserves (coutadas) in the Zambezi delta
- Primeiras and Segundas Islands Environmental Protected Area extends into the northern portion of the ecoregion.