Invasive species in the UK

What are the Ponto Caspian species, and why are they a problem for UK biodiversity?
03 November 2020

Interview with 

Paul Walton, RSPB


A small river running through a mossy, forested area


So far in the show we’ve heard about animals moving themselves and each other around, and how human activity can result in some species being moved into new habitats where they can call real problems. So what can be done to address, or prevent, this happening in the first place? Phil Sansom spoke to the RSPB’s Paul Walton about the problem of invasive species in the UK...

Paul - When it comes to aquatic species here in the UK, I think there really is quite significant threat. Now, all environments on Earth can be subject to the impact of invasive non-native species. But some are particularly vulnerable. And that is islands, as we've been hearing from your previous contributors, but also other insular habitats like freshwater bodies or freshwater habitats in this country, the upland tarns, the chalk streams, our rivers, our estuaries are really potentially quite vulnerable.

There's a group of species that we call the Ponto Caspian freshwater species that evolved over in the Caspian Black and Azov sea area in East of Europe. And have actually in recent decades, been spreading across continental Europe, sort of en masse. And it's 20 to 30 species of aquatic plants and molluscs and crustaceans and small fish. But the thing is that they all co-evolve together and they all co-exist very successfully. And when some of them establish, it improves establishment conditions for the others. And they have been moved between water bodies by people simply moving things like angling gear and boats and canoes and other equipment between different water bodies. And you get eggs and propagules moved into new catchments and they've spread right across continental Europe.

Now there's maybe four or five of these species now already in this country. The dikerogammarus, the killer shrimp, which is established in some of the water bodies in south and central England. But there are sort of 25 of them sitting in the Dutch ports waiting to come over to this country. And so I'm really concerned that we need to improve our biosecurity in this country. It's fantastic hearing Simon McCurdy there talking about the immense detail that people are studying biosecurity over in Australia. We need to start to learn some of these lessons over here in the UK as well.

Phil - Is there any way of predicting what the future is going to look like and what our outlook's going to be?

Paul - In general terms there is. We can't predict exactly which species are going to come here, but the number one route of people directly moving either deliberately or accidentally species around the world, the main pathway is international trade. Okay. So we know that there's something we need to focus on around just being extremely careful about how we are moving animals and plants and fungi around the world in our trade. And we know in this country, post Brexit, clearly there are going to be new international trading relationships developed. So we are going to have naturally new arrays of species arriving. That is one issue, I think, that we need to have our eye on.

The other, I think, is that climate change, as it progresses and progress it will, is known to be improving the establishment conditions. So species may be brought here, but for example, they're going to start to find there's less frost for example, and that is going to allow more species to get that toe hold and to establish themselves in the wild once they either escape or are accidentally released, or are sometimes even deliberately released for one reason or another.

So I think with a combination of climate change and developing international trade, there is a real risk to this country from something which we know already is actually costing us - not only our precious ecological resources and biodiversity treasures, but - something like 2 billion pounds a year, just the management at the moment. I think the key lesson is prevention and biosecurity is the key. And at the moment we're simply not investing much in this country in biosecurity, less than a million pounds a year. We have been pressing with other environmental organisations for a significant increase in the spend on biosecurity for the UK and the establishment of an invasive species inspectorate to help people to adopt best practice with regard to biosecurity.

Phil - Any final reflections on the show as well, Paul? What should people take away about how animals move?

Paul - My reflections are really around the enormity of animal movements right across the different groups. It was fascinating to hear Richard Preece talking about Tristan da Cunha. Of course, one of the Tristan islands is Gough Island. It's a UK overseas territory. It is the last refuge of the fabulous Tristan albatross. And those birds are in severe decline because of being predated by non-native mice, which were introduced onto the island through shipping. The RSPB is engaged in a project to try to eradicate those mice and save that species from extinction. So there's a whole range of non-native species issues out there. When Nina described the global biodiversity crisis, she was really right. And invasive species are one of the five drivers of that. And it's just going to have to be an integral part of our response to that crisis. Is to be much smarter about the way human beings move animals and plants around the planet.


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