Causes of biodiversity loss in coastal ecosystems. | Conservation of Biodiversity in Africa - Local Initiatives and Institutional Roles. Proceedings of the conference held at the National Museums of Kenya 30 August - 3 September, 1992.

Although far less published than loss of biodiversity on land, the loss of marine genetic, species and ecosystem diversity is a global crisis in its own right. The coastal strip (the shallow water, the intertidal area and the immediately adjacent land) is the most vulnerable as well as the most abused marine zone. Coastal ecosystems are not only an important source for essential products for mankind, including foods, medicine, raw materials and recreational facilities, but also provide ecological services that directly benefit the coastal zone. Loss of biodiversity in coastal ecosystems has both direct and indirect causes. The direct mechanisms involved include habitat loss and fragmentation, physical alteration, over-exploitation, pollution, introduction of alien species and global climate change. The root causes that drive these proximate threats lie in the high rate of human population growth, the unsustainable use of natural resources, economic policies that fail to value the environment and its resources, insufficient scientific knowledge, and weak legal and institutional systems. The ever-growing exploitation of the coast and its resources is a reflection of the steady population increase, especially in coastal zones. Habitats are changed or lost by accelerating urbanization, development of tourist facilities, industrial installations and mariculture. Land-based and upstream activities alter sedimentation and freshwater input in downstream estuaries and coastal biotopes. Contaminants from sewage disposal and agricultural runoff are rapidly increasing and areas of eutrophication and chemical pollution are expanding. Careless disposal of plastic wastes not only causes a litter problem but also widespread mortality of marine species. Exploitation of living marine resources may damage habitats and alter food webs, while mariculture generates its own pollution and may upset ecological balances by the introduction of alien species. Global atmospheric changes, which may result in altered rainfall patterns and rising sea-level, have become a matter of growing human activities have dramatically increased the intensity, pace and kind of environmental changes that lead to habitat loss and pose severe adaptive challenges to marine organisms. Response to these changes includes drastic declines of many fisheries and extinction of several species. The loss of species and ecosystems obscures the important threats to genetic diversity, which is essential for species survival in a changing environment.

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