Wildlife

'Alien' wildlife in Europe.

Animals and plants brought to Europe from other parts of the world are a bigger-than-expected threat to health and the environment.

More than 10,000 "alien" species have gained a foothold in Europe, from Asian tiger mosquitoes to North American ragweed, and at least 1,500 are known to be harmful, a new report by the European Environment Agency (EEA) said.

In many areas, ecosystems are weakened by pollution, climate change and fragmentation. Alien species invasions are a growing pressure on the natural world which are extremely difficult to reverse.

Introduced species that suddenly thrive in a new home in Europe, including parakeets from Africa or water hyacinth from the Amazon, were estimated to cost Europe at least 12 billion euros ($16.03 billion) a year.

The problem has exploded in the last 100 years. Europe had the most data but the problem was worsening worldwide. And more travel, trade and climate change were likely to aggravate the invasions.

"Invasive species pose greater risks than previously thought for biodiversity, human health and economies," the EEA said.