The major issue for coastal countries of Southern Africa is the depletion of fish stocks by unsustainable levels of harvesting. There are also increasing incidences of pollution from activities on land and from oil spills and potential impacts from sea level rise including inundation of major coastal settlements with associated damage to ecosystems, infrastructure and displacement of populations.
The Southern African coastline extends from Angola on the west (Atlantic) coast to Tanzania on the east (Indian Ocean) coast. The coast is rich in fish, seafood, mangroves and coral reefs as well as oil, diamonds and other mineral deposits. The long sandy beaches and warm waters of the Indian Ocean create good opportunities for tourism, and the many deep-water ports along the Southern African coast present opportunities for industry and export.
These coastal resources are important economically, at the subsistence level and commercially. In South Africa, for example, the annual revenue from coastal resources has been estimated at more than US$17 500 million (approximately 37 per cent of South Africa's GDP). This includes revenues from transport and handling of cargo, tourism and recreation, and commercial fishing industries (DEA&T 1998). Mangrove forests along the east coast, from Tanzania to northern South Africa, support a diversity of tree species that are used for furniture, firewood, building dugout canoes, and of which the leaves are collected for animal fodder. Plants are also used for medicinal purposes-Xylocarpus granatum, for example, is said to cure stomach problems and hernia (Sousa 1998). Mangrove forests also provide important nursery grounds and habitats for crustaceans and fish, exploited by artisans and commercial fishermen alike. Estimates of the value of the shrimp fisheries of the Sofala Bank (Mozambique), for example, are as high as US$50-60 million per year (Acreman 1999), or about 40 per cent to the country's net foreign exchange earnings (Sousa 1997). The mangrove forests also protect the coastline from storm surges and other natural hydrological influences such as high-amplitude tidal ranges and disturbances resulting from currents (Tinley 1971).
Sea level rise as a result of global climate change would cause inundation of the extensive mangroves of Mozambique and Tanzania and these would retreat, thus increasing rates of erosion of the shoreline. The coastal lagoons of Angola would also be inundated. Sea level rise is also a major threat to low-lying coastal urban centres and ports, such as Cape Town, Maputo, and Dar es Salaam. Its impacts could result in a loss of income from coastal industries and port activities throughout the sub-region, as well as loss of opportunities for development of tourism (IPCC 1998). In Tanzania, a sea level rise of 0.5 m would inundate over 2 000 km2 of land, costing around US$51 million and a rise of 1.0 m would inundate 2 100 km2 of land and erode a further 9 km2, resulting in costs of more than US$81 million (IPCC 1998).
The coral reefs off the coasts of Mozambique, South Africa and Tanzania are under threat of bleaching due to sea temperature rise resulting from El Niņo events and global climate change. In 1998, the El Niņo induced sea temperature rise of around 1°C caused the death of up to 90 per cent of the corals in the subregion (Obura and others 2000).
All countries of the sub-region, with the exception of Angola, have ratified the UNFCCC but, as most of them (with the exception of South Africa) contribute negligible amounts to global carbon dioxide emissions, more immediate mitigating measures are required. Construction of physical barriers is a short-term measure which has been implemented, but relocation of human settlements and industry could also be considered.