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WHY ALIEN SPECIES MUST BE KEPT OUT OF THE TWEED
BIOSECURITY is not a word that is familiar to many – yet, but it will become so in the future. With the globalisation of trade and the increasing numbers of people moving around the world, the transfer of new species of plants and animals, both accidentally and deliberately, from one region, country or continent to another is becoming an increasing problem. Some people mistakenly think that by introducing new plants or animals to an area, they are doing a good thing, increasing species diversity or making a new resource. However, an artificial, man-made, collection of species does not have any value as a group – there are hundreds of species of animal in Edinburgh Zoo, for example, many of them of great interest in themselves, but as a community, they have no value or interest. It is the natural community of species found in an area that is of interest, the “biodiversity”, as these are the plants and animals that naturally belong to an area and have evolved together over time. Every time a new species is brought into an area, it actually reduces the naturalness of that area, making it more artificial, more like a zoo or a botanic gardens. New species also make an area less distinctive and more like other places – for example, on the Tweed, only the fish species that can cross salt water at one stage or another of their life cycle are native to the river, because there has never been a freshwater connection between the Tweed and any other river by which purely freshwater fish could reach it. The history of the south and east of England however, is quite different – at the end of the Ice Age, when the North Sea was still partly frozen, there was a large, freshwater lagoon off what is now the Dutch coast into which both the rivers of the south and east of England and those of the northwest of the European continent drained. Purely freshwater fish – such as Pike, Perch, Roach, Rudd, Dace, Barbel etc. are therefore native to the south and east of England but not to the Tweed or to the rest of Scotland or the North of England. Every time therefore that one of these freshwater fish is introduced to the Tweed, it makes the Tweed less distinctive and more like the South of England and continental Europe.
Introductions of new species weaken the local identity of an area, making it more like any other, a process called “Ecological McDonaldisation”, since the way in which fast-food chains are changing local and national differences in food and eating habits as they spread through the world is exactly parallel to the way that ecological differences between areas are being destroyed by introductions of new species. While it is true that new species (and new restaurants) can be a resource, sometimes a very valuable one, it is at the expense of natural, local, identity, too high a price to pay for any supposed advantage. There is also the point that introduced species are generally very difficult to eradicate once in the wild, so their introduction represents a permanent ecological change, and no one individual or group has the right to make such a fundamental and unalterable change. An animal or plant that may be useful or seem desirable to one generation may be unwanted or a pest to future generations.
There are also the risks to native plants and animals from introductions – too many disasters have occurred all over the world from introductions and are well known, such as Rabbits and Cane Toads in Australia. Here in Britain we have had the near extinction of the native Red Squirrel by the American Gray Squirrel, the devastation of water birds by introduced American Mink and, most recently, the catastrophic introduction of Hedgehogs to some of the islands of the Outer Hebrides where the eggs of ground nesting birds had previously been safe from land predators and where the once large breeding populations have been greatly reduced. Hopefully, it will be possible to remove Hedgehogs from these islands, where they simply do not belong, but it is very much more difficult to remove freshwater species once they have arrived, making prevention the only real answer.
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