Species that could devastate wetlands and ‘cost millions in tax and water bills’, identified as greatest single threat to UK wildlife

A type of mussel recently identified by scientists as the greatest single threat to Britain’s wildlife of any alien species has been found for the first time in a reservoir near Heathrow airport. Discovery of the quagga mussels at Wraysbury reservoir poses a severe threat to thousands of native animals and diverse habitats. They also disrupt water supplies by blocking pipes and causing flooding.

Although the molluscs, originally from the Ukraine, grow to less than 5cm long they breed so prolifically that their vast colonies attach to hard surfaces and are difficult to remove. They are threatening to block the water supply in Las Vegas after flourishing in Lake Mead and colonising the Hoover dam’s turbines.

Wildlife experts have described them as ecosystem engineers due to their capacity to filter water, which upsets the natural balance of the food web as they eat pollutants then turn them into concentrated toxic faeces which can poison drinking water for both wildlife and people.

The Wildlife and Wetland Trust, which made the discovery last week, said the non-native mussel was “the number one most dangerous alien species” and added that the threat to British wetlands could be devastating.

Jeff Knott, WWT’s head of conservation policy, said: “This is worrying, but entirely predictable. Quagga mussels are likely to indirectly cause suffering and death for hundreds of thousands of native animals, fish and plants and cost millions of pounds in tax and water bills to protect drinking water supplies.

“These tiny mussels can be devastating but look so innocuous, which is why it’s so difficult for boaters, anglers and other water users to avoid accidentally transferring them between water bodies when they latch on to their equipment. That’s why it’s so important for all water users to remember the motto ‘clean, check, dry’ when they pack up their equipment to help slow the spread.”

He said the devastating effect of the mussels is why the UK needs stronger controls on invasive species being brought into the country as prevention is far cheaper and more effective than trying to control an established infestation. “We need to protect the UK against the next invasive species,” he added.

A trust spokesman said the WWT’s London Wetland Centre, downstream from Wraysbury “is the sort of place [where] they’ll wreak havoc with the wildlife, if left unchecked”.

The spread of quagga mussels is often due to human activity as the adult bivalves, which can produce a million eggs a season, attach themselves to boats.

The Department for Environment, Food and Rural Affairs said it would take action to tackle the threat. A spokesman said: “It is important that we take action to address the threats posed by invasive non-native species. They threaten the survival our own plants and animals and cost the economy at least £1.8bn a year

“We will be working closely with interested parties and our agencies to reduce the risk of the quagga mussel spreading any further. Users of our waterways can help with this by checking their equipment and keeping it clean and dry.”

Research by the Centre for Ecology and Hydrology in June described the molluscs as “the top ranking threat to our natural biodiversity”. It had predicted quagga mussels would arrive in the UK within the next five years.

Helen Roy, one of the scientists involved in the research, said that after looking at hundreds of species from all over the world the quagga mussel was the most likely to arrive and establish itself in the UK and pose a danger to biodiversity.

It can be hard to distinguish from the zebra mussel, another alien bivalve which is already widespread in England and Wales.