A silent horde of alien invaders are worming their way through the Alberta countryside. These creepy-crawlies came from a world away, and there’s no stopping them now.
The best we can hope to do is slow the spread of these invasive earthworms, says the head of the Alberta Worm Invasion Project.
“In North American forests, earthworm invasions have led to changes in plant, invertebrate, and songbird communities, and affected soil microbial biomass, carbon cycles, and nitrogen cycles,” said Erin Cameron, a researcher at the University of Alberta.
“The most dramatic changes have occurred in forests in the northeastern United States, where earthworm invasions have been ongoing for a longer period of time than in Western Canada.
“Since our surveys and model suggest that earthworms are still not very widespread in forests in northern Alberta, if we can slow their spread, we will be less likely to see some of the impacts observed elsewhere.”
None of the earthworm species found in Canada are native to North America, said Cameron.
“The species that are invading are European and are believed to have been introduced with plants and soil with the first European settlers,” she said, adding that, in Alberta, there are at least 14 non-native earthworm species.
And while earthworms can be found in almost every field and garden in the province, “they’ve only recently started to spread into forests” — and Cameron would like to keep it that way.
“Earthworms can consume the leaf litter layer in forests and mix it with mineral soil below,” she said. “This affects species that rely on a thick forest floor. For example, the numbers of mites and springtails living in the organic soil decrease when earthworms invade.”
Citizens can help
In an effort to track how these earthworms are spreading, Cameron — in collaboration with researchers at the University of Alberta — has developed a “citizen science program” and mobile app, to be released later this spring.
“The website for our program has sampling instructions and curricular materials for teachers, and participants can also view maps of their data and all other data that is collected,” said Cameron.
“We’re looking for participants and data from across the province, so anyone in Alberta who wants to survey in their garden, fields, forest, or any other habitat can help out by downloading the app and following the steps to sample worms.”
One such sampling technique involves pouring a mixture of water and mustard powder on the ground to bring up the earthworms, she said. “Both children and adults seem to find that pretty interesting.”
And though earthworms are considered beneficial in agriculture because of how they work the soil, producers can also do their part to help stop the spread into forests, said Cameron.
“Since earthworms don’t move very quickly on their own, producers can help reduce their spread in Alberta by avoiding introducing them at new locations, by not moving soil around to more remote forest locations or washing off ATVs before heading to remote areas.”
For more information about the Alberta Worm Invasion Project or to download the app, visit worms.educ.ualberta.ca.