ALLEGHENY COUNTY, Pa. - By the time North Park workers noticed, the damage was done.
An area of forest floor is bare of flowers, ferns and understory growth because invasive worms stripped the upper soil layer of nutrients that plant seedlings need, said Meg Scanlon, an interpretive naturalist at North Park's Latodami Nature Center.
“They've probably been here for years, and we never knew it,” Scanlon said.
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The invasive earthworms will consume even the roots of small plants, she said.
Chelsea Carver, 14, documented 12 types of invasive worms in the park — including Asian jumping worms, which eat more, multiply faster and cause more destruction than other worms, she said.
Carver, who conducted other science projects for the nature center, approached Scanlon for a biology project to tackle in her free time in June, and Scanlon asked her to study the worm problem.
“It also causes (other) animals to have to move to other locations,” Carver said. The worms consume leaf litter that otherwise would be food for native creatures.
Scanlon said most invasive species have no natural predators or natural controls. The invasive earthworms are not native to Pennsylvania, she said.
Worms purchased by homeowners for use in composting can spread to neighboring areas, she said, but worms likely got to the park through people fishing at North Park Lake and dumping unused bait onto the ground.
As part of her study project, Carver designed a sign that directs fishermen to discard unused bait in trash cans.
The sign has a QR, or quick response code, that takes visitors with smartphones to the nature center's website. It has information Carver provided about the worm problem.
Allegheny County will make 15 to 20 metal signs and place them around North Park Lake.
Park employees discovered damage from the earthworms last spring, Scanlon said.
“There's no new trees or understory growth where these worms exist. And pairing that with the deer impact and the other invasive plant species, like barberry, you know, our forests are at severe risk,” she said.
Terrence Willis, 46, fished with his wife, Tanika, 39, and their two daughters, LeQuay, 15, and Zaria, 11, on Sunday at North Park Lake.
The McKees Rocks family always donates unused bait, usually night crawlers, to other fishermen, Terrence Willis said.
“We never throw anything away,” he said.
Tory N. Parrish is a Trib Total Media staff writer. Reach her at 412-380-5662 or firstname.lastname@example.org.