LONDON, Oct. 9 (UPI) -- Nearly 100 species not native to Britain have invaded the River Thames making it one of the most highly invaded freshwater systems in the world, scientists say.
Researchers at Queen Mary, University of London, say the finding suggests legislative efforts to prevent the introduction of invasive species across Britain have been unsuccessful.
The cost to the British economy of invasive non-native species is $2.7 billion every year, a university release said Tuesday.
"We have identified 96 freshwater non-native species in the River Thames catchment and modern invasion rates (post 1961) reveal that one non-indigenous species is discovered every 50 weeks," researcher Michelle Jackson said.
"Our research suggests that globalization has facilitated species invasions because shipping activity and population size in the catchment had a positive correlation with the discovery of non-native species."
The second-longest river in Britain, the Thames flows through Oxford, Reading, Windsor and London before reaching the North Sea in Essex.
"Invasive species are major drivers of biodiversity and ecosystem service loss, and multiple invaders have the potential to amplify one another's impact," Jackson said.
"Our research highlights the need to establish how these multiple invaders interact."