Alien species – where are you from?

by Tatiana Moreno, freelance journalist, @Tatiana_Moreno

Domestic cats, the common wall lizard and horseradish are all found in England, but in fact they were once alien species. Britain alone has over 3,000 non-native species, as stated by the Royal Society for the Protection of Birds.

The International Union for Conservation of Nature (IUCN) describes the concept of invasive species as “animals, plants or other organisms introduced by man into places out of their natural range of distribution, where they become established and disperse, generating a negative impact on the local ecosystem and species.”

In other words, alien or non-native species are those that settle down in a different area than the one they belong to as a result of human intervention, which can be intentional or not.

Invasive species are a very serious problem. There are more than 10,000 alien species present in Europe and, 15% of these have a negative ecological or economic impact, according to the latest report of the European Environment Agency.

The same research claims that habitat alteration and invasive species impacts have been the major cause of species extinctions over the past few hundred years, increasing the rate of extinction by about 1,000 percent.

But there are always two sides of the story, and in some occasions, the arrival of a new species does not cause any harm to the ecosystem, like the rainbow trout or the sweet chestnut in England.

But, we should take into account that there are many more negative aspects to this issue than positive outcomes. Non-native species are not only threaten the new ecosystem, they can be a risk to human health (new diseases) and economy (tourism, fisheries, agriculture).

It is true that the movement of species is not a recent problem and in fact, it has happened for thousands of years, since the Roman Empire. But the problem has increased in recent decades due to globalisation. It is very difficult to control the movement of species nowadays.

Trade, transport, travel and tourism have made it a lot easier for pathogens, pests, predators and insects to travel around the world and arrive at a new ecosystem. Instead of growing the local species, sometimes farmers bring different types of plants to their area because they give better yields. It can be as simple as having an exotic pet at home, like a snake or a tarantula, which goes out of its cage and gets into the surrounding environment.

That is the main reason why this problem has to be approached internationally and not only locally. Efforts should be put together to stop this threat to nature and to avoid biodiversity loss.