ALIEN species are on the march, wreaking havoc among crops and natural
ecosystems. But while governments have signed an agreement to halt these
invasions, scientists warned this week that they lack the knowledge and the
power to do so.
Under the UN Convention on Biological Diversity, countries have agreed to
鈥渃ontrol or eradicate those alien species which threaten ecosystems,
habitats or
species鈥� and to prevent their introduction. This is 鈥渁 very sweeping charge鈥�,
Harold Mooney of Stanford University in California told a conference on alien
species in Trondheim, Norway, earlier this week. He said that with 鈥渙ur current
knowledge base and management tools鈥�, the task was one 鈥渢hat we cannot
蹿耻濒蹿颈濒鈥�.
Alien species are 鈥渙ften aggressive, since they have escaped, at least
temporarily, their predators鈥�, said Mooney, who is devising a global
strategy to
combat them for the Scientific Committee on Problems of the Environment,
part of
the International Council of Scientific Unions.
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The damage caused by just one introduced species can be huge. In 1981,
a comb
jellyfish hitchhiked into the Black Sea from the US in a ship鈥檚 ballast. The
species disrupted the ecosystem to such an extent that, six years later, fish
catches in the Black Sea had declined by 90 per cent.
Mooney warned that population growth and increased international trade are
multiplying the number of invasions and the vulnerability of ecosystems to
outsiders. He called for 鈥渞apid assessment鈥� systems to monitor the progress of
invaders.
But several speakers at the conference argued that stronger action is
needed.
Michael Soul茅 of the University of California, Santa Cruz, warned
that in
the absence of tough laws and policing 鈥渢he likelihood of successful
control and
elimination is negligible鈥�.