Five of the invaders from the Ponto-Caspian region around Turkey and Ukraine have already gained a foothold in the UK and ten are just across the North Sea in Dutch ports.
Once here they are expected to rapidly spread to Scotland where, as well as killing off native species, they also spoil the environment for other species including trout and salmon.
The invader which poses the greatest threat to “national bio-security” – Quagga mussels – have already been discovered at Wraysbury reservoir, near Heathrow Airport, the Wildfowl and Wetland Trust confirmed.
In the US, the species is flourishing in Lake Mead, formed by the Hoover dam, and is threatening to block water supplies to Las Vegas.
Researchers from the University of Cambridge also said that Britain’s shrimps are under threat from the killer shrimp – dubbed the “pink peril” – as well as from the demon shrimp and bloody red shrimp.
A study published in the Journal of Applied Ecology, looked at 23 invasive species that originate from the waters of the Black, Azov and Caspian seas.
Areas in immediate danger are the lower reaches of the Great Ouse, Thames and Severn rivers and the Norfolk Broads. The report’s co-author, Dr David Aldridge, warned of an “invasional meltdown” and said: “We are at a tipping point. We’ve been watching species heading our way from the Ponto-Caspian region for the past 20 years or so. They are all building up in the Rhine system just over the sea.
“We think, particularly now that the quagga mussel has just arrived, we are about to have a big meltdown. Pretty much everything in our rivers and lakes is directly or indirectly vulnerable.
“The invader we are most concerned about is the quagga mussel, which alarmingly was first discovered in the UK just two weeks ago. This pest will smother and kill our native mussels, block water pipes and foul boat hulls. We are also really worried about Ponto-Caspian shrimps, which will eat our native shrimps.”
The animals arrive in the ballast water of ships, aquatic gear such as fishing nets or hidden among ornamental plants.
Dr Aldridge added: “If we look at the Netherlands, it is sometimes hard to find a non-Ponto-Caspian species in their waterways. In some parts of Britain the freshwater community already looks more like the Caspian Sea.”
The scientists point to the example of the zebra mussel, a relation of the quagga, first seen in the UK in 1824 and now widespread.
Sarah Chare, deputy director of fisheries and biodiversity at the UK Environment Agency added: “Invasive species cost the UK economy in excess of £1.8 billion every year.”
Dates and locations of the first British reports of 48 other freshwater invaders from around the world show that a third emerged in the Thames river basin, followed by a fifth in Anglian water networks and a sixth in the Humber.
The Department for Environment, Food and Rural Affairs said it would be working to reduce the risks of the quagga mussels spreading any further.