'The aliens to watch': how the humble earthworm is altering the Arctic

After hitching a ride with humans, the species has colonised entire areas and may be making the soil too fertile, say scientists

They are a gardener's best friend, good for the soil and a treat for birds. But the humble earthworm may not always be good news, according to a study that suggests invasive earthworms could be making Arctic soils too fertile.

The earthworm is not typically thought of as an invasive species. Most parts of Europe have earthworms so we never really saw them as a problem," says lead researcher Dr Gesche Blume-Werry, an ecologist from the University of Greifswald in Germany. But Blume-Werry and her colleagues realised that more and more spots in the Arctic have worms because humans brought them there".