A look at alien species in Europe
By David Alderton

Just as the subject of invasive species has recently been high on the agenda as far as the pet trade and owners in the U.S. are concerned, so a similar situation is developing in Europe. The horticultural industry has become a focus of concern, not just because of the way in which economically dangerous invertebrates can spread via movements of plants, but also because of the trade in plants themselves. In the U.K., recently proposed government regulations would outlaw the sale of some 15 different plants. This may not sound especially significant, but it would have a dramatic impact on the aquatic industry, costing an estimated $9 million since the list features some of the most popular coldwater plants for aquaria and ponds.

The Convention on Biodiversity, to which more than 170 governments are now signatories, is examining the subject of alien species this summer. Defined as species moved outside their natural range, only a very small proportion of these are likely to become invasive species since a diverse set of criteria--economic, social and, of course, biological--have to occur before that status is reached.

Agencies worldwide are now tasked with carrying out risk analyses for a whole host of plants and animals, but as the debate in the U.S. highlighted, local controls are most effective rather than far-reaching bans--and are more likely to engender public support. It is obvious that most species that could live in Florida or Hawaii would die rapidly in the middle of an Alaskan winter, and regulations need to be framed accordingly.

The current U.K. proposals reflect the problem of trying to internationalize the issue. Among the 15 economically significant species of plants that could be banned from trade, there is the water hyacinth (Eichhornia crassipes). Certainly, this native of South America has become a problem in various warmer parts of the world, growing so densely that it can block waterways. Yet, even in the mildest parts of southern England, there is no chance that it could become invasive. Any left outside in winter will turn brown and die when exposed to the first frosts of winter, if not before.

There is no evidence whatsoever that this popular aquatic plant, grown for its attractive flowers, therefore presents any threat to waterways in the U.K. It has been imported regularly for probably more than 70 years, and with annual sales said to be worth around $1.5 million, it is one of the mainstays of the pond industry. Banning it would simply cost the industry money.

Another issue is that in cases where plants have established themselves in the wild, there is little point prohibiting their sale, because they are already so widespread. Canadian pondweed (Elodea canadensis) and several similar oxygenating plants fall into this category. Keith Davenport, chief executive of the Ornamental Aquatic Trade Association (OATA) described the proposal to ban such plants as being “unlikely to have any impact. It’s a bit like shutting the stable door after the horse has bolted, run round the paddock five times and galloped off.”

Canadian pondweed was actually spread into British waterways by the timber trade, and is very widely cultivated both in ponds and in coldwater aquaria. It is essentially perceived as a U.K. native. This plant has become particularly significant as a spawning site for newts, with females wrapping their eggs in the leaves, and its removal could be seriously detrimental to wild populations of these amphibians.

The Environment Agency--the government’s own advisory body--has also cautioned that a ban on sales of these aquatic plants could actually make the situation worse rather than better. In a statement, it reported, “Alternative native plants will need to be promoted and marketed. There is a danger that publicity will result in a sudden upsurge in problems caused by householders or businesses getting rid of these plants already in their aquaria, ponds or gardens. Care will be needed in managing this, particularly in relation to attractive or popular plants such as Canadian pondweed and parrot's feather."

A final decision from the government is expected later this year, but the issue of invasive species is in danger of getting out of control. Just as the financial shocks have provided a jolt to the banking community, it is hoped that as government budgets become tighter, this prolificacy will diminish. Such problems need to be handled at local level, where action can be taken more quickly, effectively and at far lower cost.

There isn’t a purpose-- other than job creation-- for a plethora of scientists to speculate globally about what may or may not happen with a particular species. Trade and the associated movements of plants and animals are nothing new--it’s a process that has been going on for millennia. Throughout this entire period, as far as pets are concerned, there is only one species that became globally invasive--and that occurred long before such matters were debated. It’s Felis cattus, the domestic cat. <HOME>

David Alderton is a journalist based in the U.K. who writes about all things pet-related. He is also the editor of a recently launched herp magazine in Britain.