Human impacts on biodiversity in African coastal ecosystems: an overview. | Coastal systems and sustainable development in Africa. Proceedings of a UNESCO Regional Seminar on Human Impacts on Coastal Ecosystems, their Response and Management Problems ROSTA, Nairobi, 5-9 April 1993.

The coastal ecosystems of many African countries contain some of the most biologically diverse and productive habitats but they are also the most vulnerable as well as the most abused marine zone. Coastal ecosystems are net only an important source of essential products for consumptive, commercial and recreational use, but also provide ecological services that directly benefit the people. Due to the many living and commercial opportunities it offers, the coastal zone contains densely populated areas. Those areas especially are seriously threatened by human activities with consequent loss of their biodiversity. The direct mechanisms include habitat loss and fragmentation, physical alteration, over-exploitation, pollution, introduction of alien species and global climate change. Human impacts on coastal ecosystems are widespread. Habitats are changed or lost by the urbanization, development of tourist facilities and industrial installations, land reclamation and conversion, dredging and mining activities. Land-based and upstream activities alter sedimentation and freshwater input in downstream estuaries and coastal biotopes. Contamination from domestic and industrial sewage disposal and from agricultural runoff is also rapidly increasing and leading to eutrophication and chemical pollution. Disposal of solid wastes, especially plastics, not only causes a litter problem but also widespread mortality in marine species. Some types of exploitation of living marine resources may damage habitats and alter food webs, while maricuIture generates its own pollution and may upset ecological balances by the introduction of alien species. Human activities have dramatically increased the intensity, pace and types of environmental changes with an impact upon the coastal habitats and the resources they sustain. These changes may lead to the drastic decline of coastal fisheries and loss of biodiversity. The main root cause which drives these human activities lies in the high rate of human population growth, economic policies that fail to value the ecological service of the environment and its resources, insufficient scientific knowledge, and weakness in institutional and legal systems.

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