By Francesca Dawson Pell
Invasive species are species that are not native to an ecosystem or country. Many have been introduced to the new area by humans, either accidentally or deliberately. There are a whole range of organisms that can be invasive, from animals and plants to tiny micro-organisms. Should we worry about them? Some invasive species can cause damage to the environment, the economy and even harm human health. In the UK alone the control of invasive species costs £1.7 billion every year (1).
Which invasive species do we find in the UK, and how did they get here? According to the GB Non-native Species Secretariat, over 3000 species in the UK are listed as invasive. Species have been introduced to the UK from all over the world, excluding Antarctica. They have spread to the UK through a variety of different methods including: escaping from the pet trade, accidental transport in cargo ships, planes, trains, or lorries and even some deliberate introductions to new habitats without consideration of the environmental or economic consequences.
The grey squirrels you see in the local park or garden are descended from North American or Canadian squirrels. They are causing the local extinction of the red squirrel (the UKs native squirrel species) by competing with them for food and transmitting squirrel pox – a deadly disease. They may be colourful, but ring-necked parakeets are also invasive in the UK and can cost the agricultural industry a lot of money by eating their way through ripe fruit. They also carry diseases that can infect chickens and some diseases that can infect humans in close contact.
Invasive species can also be found in aquatic environments. For example, signal crayfish originally from North America are pushing UK species of crayfish towards extinction by competing with them for shelters and spreading disease. Signal crayfish also dig deep burrows that can cause riverbank erosion and even influence flooding. Plants can be just as bad as animals when it comes to the impacts of invasions. Japanese knotweed for example can have structural impacts on both biological communities and habitats. Controlling Japanese knotweed is predicted to cost hundreds of millions of pounds every year around the world.
Scientists study a whole range of topics to help us understand more about invasive species: from studying their DNA, to mapping their range and spread in the new environment, and recording their behaviour. By doing so they assess the impacts invasive species have on the environment, and make predictions about the threats and conservation concerns invasive species can cause.
What can you do to help?
There are lots of different actions you can take if you want to help prevent the spread of invasive species. These range from contributing to citizen science by reporting when and where you detect an invasive species on a mobile application or a website (for example iRecord Ladybird or PlantTracker), to helping out at a local event to eradicate invasive species from an area. It also helps to remember to “Check, Clean and Dry” any equipment that has been in water as aquatic invasive species can be transported on unclean equipment (www.nonnativespecies.org/checkcleandry/).
To find out more about invasive species and what you can do to help:
1. The Wildscreen Arkive page on UK invasive species
2. The GB non-native species secretariat
About the Author
I am a PhD student at the University of Sheffield studying invasive monk parakeets in Spain, their DNA and their social structure.