|Cumulative number of aquatic introductions
Cumulative number of aquatic introductions
rose fast in the second half of the 20th century
Source: FAO 1998 and Wellcome 1988
Invasive species are organisms (usually
transported by humans) that successfully colonize native ecosystems. Such
species have been a major threat to native species through the effects
of predation, alteration of habitat or disruption of ecosystem processes.
Notable terrestrial examples include the loss of many endemic land snail
species of French Polynesia following the introduction of the predatory
snail Euglandina rosea, and the decline in New Zealand's native birds
due to the introduction of Australian brushtail possum. Aquatic examples
include the introduction of the predatory Nile perch Lates niloticus to
Lake Victoria around 30 years ago, which contributed to the apparent extinction
of 250 endemic species of cichlid fishes (Harrison and Stiassny 1999).
The number of aquatic introductions rose rapidly during the second half
of the 20th century (see graph).
The CBD recognizes the importance of invasive species
as a global problem and calls upon contracting parties to prevent the
introduction of, control or eradicate those alien species that threaten
ecosystems, habitats and species. In response to a recommendation from
the CBD in 1996, the Global Invasive Species Programme (GISP) was developed,
which is coordinated by the Scientific Committee on Problems of the Environment
(SCOPE), in collaboration with IUCN, Centre for Agriculture and Biosciences
International and UNEP. The programme will review current knowledge on
invasive species and develop new tools and approaches to deal with the
problem both locally and globally.