Causes and impacts of invasive alien species
Globalization has resulted in greater trade, transport, travel and tourism, all of which can facilitate the introduction and spread of species that are not native to an area. If a new habitat is similar enough to a species’ native habitat, it may survive and reproduce. For a species to become invasive, it must successfully out-compete native organisms for food and habitat, spread through its new environment, increase its population and harm ecosystems in its introduced range.
Most countries are grappling with complex and costly invasive species problems. For example, the annual environmental losses caused by introduced pests in the United States, United Kingdom, Australia, South Africa, India and Brazil have been calculated at over US$ 100 billion (CBD, 2006). Addressing the problem of invasive alien species is urgent because the threat is growing daily, and the economic and environmental impacts are severe.
Examples of Invasive Alien Species
• Native to the Caspian and Black Seas, Zebra mussels (Dreissena polymorpha) affect fisheries, mollusc diversity, and electric power generation in the Great Lakes in North America and Mississippi basin
• Native to the Amazon basin, water hyacinth (Eichhornia crassipes) has invaded tropical habitats worldwide spreading to more than 50 countries on five continents. Water hyacinth blocks waterways, decimates aquatic wildlife and the livelihoods of local people and creates ideal conditions for disease and its vectors
• Native to the Indian sub-continent, the ship rat (Rattus rattus) have caused extinctions and catastrophic declines of native birds on islands and have spread throughout the world
• Deadly new disease organisms, such as avian influenza A (H5N1), attack humans and animals, in both temperate and tropical countries
• Aquatic invasive species have done serious damage. A unique approach using music as a medium to help prevent the spread of aquatic invasive species in lakes and rivers is being used in Wisconsin (USA).
The Convention on Biological Diversity and its members (there are 191 Parties, as of October 2008) recognize that there is an urgent need to address the impact of invasive alien species. Article 8(h) of the CBD states that, “Each contracting Party shall, as far as possible and as appropriate, prevent the introduction of, control or eradicate those alien species which threaten ecosystems, habitats or species”. The CBD sets global priorities, guidelines, collects information and helps to coordinate international action on invasive alien species.
The CBD has adopted guidance on prevention, introduction and mitigation of impacts of alien species that threaten ecosystems, habitats or species, which can be accessed on the CBD website (Decision VI 23). The website also provides further information on invasive species and relevant decisions of the Conference of the Parties to the CBD.
Prevention is the most cost-efficient and effective method against invasive alien species. Halting the establishment of potentially invasive species in the first place is the first line of defense. Governments conduct customs checks, inspect shipments, conduct risk assessments and set quarantine regulations to try to limit the entry of invasive species. However, global inspection and risk analysis capacity is usually not sufficient.
It is also important to develop economic tools and incentives for the prevention of introductions, and to educate the general public and raise awareness so that informed decisions can be made about how to limit introductions and their spread. Invasive alien species are a global issue that requires collaboration among governments, economic sectors and non-governmental and international organizations. Individuals also have a large part to play, including policymakers, consumers, horticulturalists, landowners, educators, youth and recreationists.the Problem
International Biodiversity Day - May 22nd
May 16, 2009