Africa's coastal ecosystems are also threatened by industrial pollution, mining and oil exploration activities. Most industries still discharge their untreated wastes directly into rivers and, ultimately, the oceans. The Mediterranean basin is now one of the most polluted, semi-enclosed basins in the world. But pollution also affects unenclosed seas. Petrochemical complexes add to the problem.
Similar situations exist in Egypt, Libya, Morocco and Tunisia.
In many areas, coastal erosion is a growing problem, driven by natural processes which are exacerbated by the upstream construction of dams and the development of other forms of coastal infrastructure such as artificial lagoons and the clearing of mangrove systems. In the longer term, climate change is also a major threat to critical coastal ecosystems such as the Nile, the Niger and other low-lying deltas and oceanic islands, particularly in the Indian Ocean, which may be inundated by rising sea levels. The Indian Ocean contains about 15 per cent of the world's mapped coral reefs, of which more than one-half is estimated to be at risk from human activities.