Threats to Biodiversity
In addition to some of the threats previously mentioned for specific ecosystems, environmental pollution is an increasingly major threat to biodiversity in many countries. Pesticide residues have reduced the populations of several bird species and other organisms. Both air and water pollution stress ecosystems and reduce populations of sensitive species, especially in the coastal zones where there is a high population density and industrial activity. As regions continue to industrialize, the adverse impact of pollution on biodiversity will become even more severe unless cleaner production technologies are adopted.
Threats to Africa's biodiversity. Source: Africa Environment Outlook.
The introduction of exotic or invasive species over the past century also contributed to biodiversity loss as some alien species 'out-competed' native vegetation. For example, parts of the South Africa and eastern highland grasslands in Zimbabwe were invaded by exotic Australian species, and threatened the survival of indigenous species. Island species, such as those found in the Indian Ocean, are particularly vulnerable to extinction caused by competition or predation. Fortunately, the introduction of exotic species is declining, a positive trend that will probably continue as regulations on the importation of biological resources become increasingly stringent.
Civil conflict and war have also led to significant ecological damage and biodiversity losses in and outside protected areas, as well as to the marginalization of environmental management institutions and conservation programs. By 1991, the wildlife populations of national parks and reserves in Angola had been reduced by civil war to only 10% of their 1975 levels. Similar losses are likely to have occurred in the Great Lakes region during the past five years.
Climate change is the latest emerging threat to biodiversity in Africa. It has already been identified as a contributing cause in the decline of amphibian populations, due to drastic reductions in the volume of water bodies after persistent dry weather in combination with intensified human activities along the shorelines.
