Environmental Engineering Reference
In-Depth Information
8
frameworks for invasive species
Maj De Poorter
The natural biogeographical barriers of oceans, mountains, rivers, and deserts pro-
vided the isolation in which species and ecosystems evolved. Increasingly, these
barriers have lost their effectiveness as economic globalization has resulted in an
exponential increase in the movement of organisms from one part of the world to
another (Carlton 1999; McNeely
et al
. 2001). Increasing volumes of trade, travel,
and tourism have led to more species than ever before being moved around the
world, on land, in the air and sea. For instance, a billion tons of ballast water is
contained in ships per year and
daily
at least 10,000 species are being transported
around the world in it (Carlton 1999). Invasive alien species (IAS), as defi ned
by the Convention on Biological Diversity (CBD), are those alien species whose
introduction and/or spread threaten biological diversity (CBD 2002).
Similar IAS problems are repeatedly faced in diff erent parts of the world. For
example, water hyacinth (
Eichhornia crassipes
) is a problem in many tropical fresh-
water bodies worldwide, including waterways in Florida (USA), Kafue (Zambia),
Lake Victoria (Kenya), and Bhopal (India). Sharing information and expertise
internationally on the ecology, impacts, and management of such IAS is hence
important (De Poorter and Browne 2005). In addition, knowledge and informa-
tion on a species' past invasiveness elsewhere is crucial to prevention, early detec-
tion, and rapid response, as these are key factors in identifying risks of invasiveness
for species newly introduced, and species not yet present. (Wittenberg and Cock
2001; De Poorter and Clout 2005; De Poorter
et al
. 2005). International pro-
grammes can assist with this.
IAS have the ability to spread across administrative or political boundaries and
they do not respect national borders. Species introduced into one nation can often
easily spread to neighbouring nations, either without further human agents (if
there are no biogeographical barriers) or by secondary introductions (e.g. uninten-
tionally via transport or trade). In order to be eff ective, management must be able
to cut across political boundaries, because unilateral action by countries will not be
