Big Worm Week seeks public's help in finding worms

Researchers investigating the impact of non-native earthworms on the Northland's forests are again asking for volunteers to grab a shovel and dig in.

The third annual Big Worm Week is set for Sept. 25 to Oct. 3, when volunteers will fan out across the western Great Lakes region in backyards, fields and forests to coax worms out of the ground, count them and identify the species.

The project, conducted at the same time each year, helps scientists compare data from year to year on where worms are and at what densities.

It's also a chance for students and nature lovers to learn more about exotic earthworm invasions, how to identify earthworms, how to create experiments in earthworm observatories and make displays for nature centers or science fairs.

"We get everyone from grade-school science classes to retired people.

Anyone can do it, and you can get as involved as you want," said Ryan Hueffmeier, project coordinator for the Natural Resources Research Institute of the University of Minnesota Duluth.

Volunteers can do as little as simply confirming the presence of worms in their yard to conducting experiments to coax worms out of the ground to take samples to send in to researchers.

There are about 15 species of earthworms in the region and all of them are foreign, imported (usually accidentally) from Europe or Asia and often spread by anglers. Over the past 20 years scientists have shed more light on earthworms' impact on trees, plants, wildlife and even the makeup of forests that developed for 10,000 years, since the last glaciers, without worms.

Studies by UMD professor Cindy Hale and others have found the worms' impact especially intrusive on hardwood forests.

The earthworms eat leaves that create the important duff layer on the forest floor and are capable of eliminating the layer completely. Big trees survive, but many young seedlings perish, along with many ferns and wildflowers. That changes what kind of trees are in a forest.

In some areas heavily infested by earthworms, scientists also have found increased soil erosion that can affect water quality of streams and other waterways.

"And we have a new worm moving north called amynthas, an Asian worm, that can grow to huge densities and produce what people have described a 'nothing grows here' syndrome," Hueffmeier said. "We don't think they are this far north yet, but if they are, the Big Worm Week volunteers will help us find out."

While an estimated 90 percent to 95 percent of the region already is saturated with invasive worms, anglers are asked to avoid spreading crawlers and other bait worms by throwing excess worms in the trash rather than releasing them.

"You can see through the research how worm populations have radiated out from popular fishing lakes across the region," Hueffmeier said. "We're asking people to pass them on to another angler or put them in the garbage."