The value of the coastal zone and oceans

The coastal zone and oceans of Sub-Saharan Africa constitute a huge storehouse of food, energy, and mineral resources that, if exploited rationally, could be the basis for sustainable development. The coastal zone is in addition a site of human habitation and of concomitant infrastructures for agriculture, industrial development, recreation, and communication (including harbours and ports).

The northern and southern sectors of the western African coastline are the scene of periodic profound upwelling, and upwelling, although weaker, has also been reported in the equatorial sections (Longhurst 1962; Ibe and Ajayi 1985). On the eastern African coast, the picture is much the same, and the Ras Hafun upwelling off the northern coast of Somalia has been extensively described (Newell 1957, 1959; Winters 1976). These areas of upwelling are particularly rich in fish production. Various species of crustacea, including lobsters, deep water shrimps, and prawns, are common. In the coastal lagoons, fish, prawns, and molluscs are also abundant and help to sustain the needs of local populations.

In addition to species of economic importance, there are vulnerable and endangered species such as sea turtles, dugongs, and manatees whose preservation contributes to marine biological diversity (Howell 1988a). Waterbirds are also important; over 100 species from over 25 families are associated with the eastern African coast but are threatened (Howell 1988b).

Some of the coastal countries in Sub-Saharan African are, to varying degrees, oil producers and a few, such as Nigeria and Gabon, are important exporters; others have important refineries and the potential for the development of further production and refining appears substantial. Besides oil and gas, commercial energy production is dominated by hydropower and coal. A survey of the potential of ocean energy in the West and Central African region noted that attractive resources exist for ocean thermal energy conversion, oceanic bioconversion, tides and salinity exchange, but the prospects for wave and current energy are rather poor, except along the southern African coastline, where it has been determined that a favourable 10 kW/m of waterfront is available up to 1 km offshore and about 50 kW/m of waterfront up to 30 km offshore (UNEP 1983).

Non-energy mineral resources are exploited in the coastal zone of Sub-Saharan Africa. These are mostly placer minerals (e.g. in Sierra Leone and Tanzania) and vast deposits of construction materials, including sand, gravel, and limestone. Phosphate mining and salt extraction are ongoing activities in some sectors of the African coastline, as is open-pit mining. Lead-silver ores were previously quarried in Kinangoni, Kenya. In addition, the coastal zone of Africa is known to have the potential to produce the vast array of minerals that would be expected from Africa's present-day geology and evolutionary history (Ibe 1982; Ibe et al. 1983).

The coastal zone and oceans, with their ecosystems of coral reefs, seagrass beds, mangroves, etc., are repositories of biological diversity in addition to serving as food "regenerating" factories.

Owing to the pattern of early contacts with the outside world, which were mainly coast based, most African cities of note are coastal cities. For example, in western Africa, the capitals of all but three of the countries from Mauritania to Namibia are situated on the coast and it is on the coast that the major industrial developments are taking place. In Ghana, 35 per cent of the population live in towns and 60 per cent of industry is concentrated in the coastal Accra/Tema metropolis. In Nigeria, about 10% of the total population of over 80 million live in Lagos, which is also the centre for 85% of the country's formal industry. The picture of coastal development in eastern Africa follows a similar pattern (Portmann et al. 1989). To promote international and national communication (transport) and trade, harbours and ports have often been constructed that are "out of tune" with the natural environment. Tourism is a booming industry in eastern Africa and a promising one in western Africa. Agriculture, including fishing and aquaculture, is practiced on a largely artisanal, sometimes industrial, scale.

The coastal zone and oceans serve a number of indirect functions that nevertheless add to their usefulness as an integral component of a country's socio-economic fabric. Such functions include the removal of wastes, protection from storms, absorption of atmospheric carbon dioxide (CO2), mediation of climate, purification of air, and recreation.