Alien travels

Forest and Bird, Issue 282, 1 November 1996, Page 8

Alien travels

THE WORLD'S largest nongovernment conservation gathering has been warned that the global movement of invasive species into new habitats is a multi-billion dollar problem that is not being directly or adequately addressed by international agreement. A report from the Species Survival Commission of the Swiss-based World Conservation Union (IUCN) to the IUCN’s congress in October called on governments and trade organisations to put numbers on the benefits and costs of species moving into new habitats as a result of human activity. The report argued that the spread of such species is on a par with habitat

loss as the main reason for the decline of biological diversity. "If we don’t get a handle on this problem soon we will lose huge tracts of biodiversity," said the commission’s Wendy Strahm. "Only the top competitive species in each area will survive. There is no sense in saving areas for conservation if we then allow them to be invaded by alien species." Among the exotic invasions listed by the commission were: » zebra mussels carried in ballast water from the Baltic Sea a few years ago which have invaded the Great Lakes bordering the United States and Canada. They are now spreading into inland lake systems where they kill clams, reduce food available for fish, and clog electric turbines and water pipes. No control is known. b an exotic virus introduced into Australia through the thriving international trade in ornamental fish that is causing a rapid decline in frog populations in Queensland. » water hyacinth introduced to China from South America and encouraged as an ornamental plant, livestock feed and an absorbent of heavy metal pollution. As a weed of lake systems it has caused local extinctions of several native plant and

animal species. It is also a huge problem in parts of West Africa where it clogs waterways. The problem has grown tremendously, said IUCN director general, New Zealander David McDowell, as the world economy has reached into virtually every corner of the earth. Estimates of the direct costs (without environmental, human health and regulatory costs) in the US alone of invasive weeds is over $5 billion a year. "What’s needed is some leadership from international organisations and governments before the environment pays the full costs of the invasive species trade," said Strahm. "If we are shifting to a policy of user pays in other areas, then we should do the same in the area of trade. Certainly those who benefit should pay their expenses."