Countdown 2010

Invasive Alien Species

Definitions

"Alien invasive species" means an alien species which becomes established in natural or semi-natural ecosystems or habitat, is an agent of change, and threatens native biological diversity.

"Alien species" (non-native, non-indigenous, foreign, exotic) means a species, subspecies, or lower taxon occurring outside of its natural range (past or present) and dispersal potential (i.e. outside the range it occupies naturally or could not occupy without direct or indirect introduction or care by humans) and includes any part, gametes or propagule of such species that might survive and subsequently reproduce.

Importance

Invasive or alien species can have serious and sometimes irreversible environmental and socio-economic impacts on native ecosystems, for example the effects of the marine ctenophore Mnemiopsis leidyi on the Black Sea fisheries (Shiganova 1998). Many of these species are characterised by their adaptability to new environments making them successful competitors against native species. The CBD rates the threat posed by invasive species, globally, second only to that of habitat loss (CBD 2001). Costs are felt not only in terms of prevention, control and mitigation, but also from the reduction in ecological services of the native species being affected. The impact of invasive species has increased globally with increases in mobility, trade and tourism. In Europe this process has increased due to economic uses of species in agriculture, fisheries, aquaculture, forestry and horticulture. Recently controversy has surrounded the possible introduction of genetically modified organisms (GMO) or pathogens that may have unknown effects on native (targeted or non-targeted) species.

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