London, Oct 13 (IANS): With five of the most high-risk freshwater invaders from the Ponto-Caspian region around Turkey and Ukraine now discovered in the Wraysbury river in London, Britain faces serious threat to its national biosecurity, says a study.

With at least ten more of these high-risk species established just across the channel in Dutch ports, Britain could be on the brink of what they descibe as an 'invasional meltdown': positive interactions between invading species cause booming populations, which colonise ecosystems - with devastating consequences for native species.

Once the species reach coastal areas of the Netherlands, they are transported across the channel in ballast water taken on by cargo ships, or hidden in exported ornamental plants and aquatic equipment such as fishing gear.

"Pretty much everything in our rivers and lakes is directly or indirectly vulnerable," said David Aldridge, co-author from the University of Cambridge in Britain.

"The invader we are most concerned about is the quagga mussel, which alarmingly was first discovered in Britain just two weeks ago," Aldridge added.

"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," Aldridge noted.

For the study, the researchers did an in-depth analysis of all reported field and experimental interactions between the 23 most high-risk invasive Ponto-Caspian species.

British reports of 48 other freshwater invaders from around the world show that 33 percent emerged in the Thames river basin, making it the Britain hot spot for invaders, followed by Anglian water networks (19 percent) and the Humber (15 percent).

The study appeared in the Journal of Applied Ecology.