PrtyMolusk
04-03-2004, 08:41 AM
Howdy-
The following article is qouted from the front page of today's Oakland Press.....
To say I was surprised is an understatement !
Lowly worm is actually invader
Web-posted Apr 3, 2004
By BOB GROSS
Of The Daily Oakland Press
Consider the earthworm.
One of the humblest of creatures, it exists to eat, excrete and make more earthworms.
And for years, people have been told that earthworms are good, that they're the farmer's friend, that they aerate and fertilize the soil.
But evidence is mounting that the 15 species of earthworms in Michigan and other Northern states are creatures out of place that may be wreaking significant damage on native ecosystems.
It turns out that earthworms - like zebra mussels, purple loosestrife and starlings - come from elsewhere.
"Any worm you see, baby," said Cindy Hale, a forest ecologist at the Natural Resources Research Institute in Duluth, Minn. "The grayish yellow, the ones that people call angleworms, leafworms, red wrigglers, nightcrawlers.
"They're all exotic, and they're all European."
There were no earthworms in the north woods before European settlement. If there ever were any, Ice Age glaciers probably took care of them.
"In fact, all of the deglaciated area essentially, anything that was glaciated, the earthworms were wiped out," said John Zawiskie, a geologist at the Cranbrook Institute of Science in Bloomfield Hills.
"Even after deglaciation, for thousands of years, the ground was frozen solid. We had tundra here in Oakland County."
There are native earthworms in North America, said Hale, but they live in the southern half of the continent where the ice sheets didn't reach. The worm that slithers out onto sidewalks after rains, that generations of kids have impaled on hooks in search of bluegills and perch, came here in the ballast of ships and the root balls of imported plants.
Unfortunately, the forest had already re-established itself by the time that happened, Zawiskie said.
"The return of forest way outpaced the migratory ability of native earthworms, so essentially for the last 10,000 years a lot of these northern hardwood forests evolved without any native earthworms," he said.
Worms are spreading, however, into new areas - and scientists know where to place the blame.
"Fishing bait is a huge factor in terms of the continued transport of earthworms across the landscape," Hale said.
She has found a high correlation between what she calls earthworm invasion fronts in Minnesota and areas that support fishing activity - such as lakes, streams and boat launches.
The problem is anglers dumping their bait.
"Sure, you've done it, haven't you?" Hale said. "So have I.
"But add up the numbers, and it gets pretty big quickly."
The situation is being taken seriously in Minnesota, where the state's Department of Natural Resources has a program with a poster urging anglers to "Contain Those Crawlers" by not dumping unused bait in the woods. The state wants anglers to instead dispose of worms in the trash.
Hale said ecologists have already noticed changes in the composition of the forest floor and among plant communities that evolved with organisms that decompose leaf litter much more slowly than do the ravenous earthworms.
"They remove the forest floor," Hale said. "In these sugar maple-dominated hardwood forests, under worm-free conditions, you would get the establishment of very thick spongy forest floor up to 10 centimeters or more which is composed of leaf litter."
That leaf litter provides nutrients for native plants and habitat for animals such as salamanders, small mammals and ground-nesting birds.
It's not that worms are necessarily bad, Hale said. It's just there are places where they don't belong.
"Everything you've ever heard about them being good in gardens and farming soils is true," she said.
"(But earthworms) can have quite deleterious effects in a native worm-free hardwood forest."
The following article is qouted from the front page of today's Oakland Press.....
To say I was surprised is an understatement !
Lowly worm is actually invader
Web-posted Apr 3, 2004
By BOB GROSS
Of The Daily Oakland Press
Consider the earthworm.
One of the humblest of creatures, it exists to eat, excrete and make more earthworms.
And for years, people have been told that earthworms are good, that they're the farmer's friend, that they aerate and fertilize the soil.
But evidence is mounting that the 15 species of earthworms in Michigan and other Northern states are creatures out of place that may be wreaking significant damage on native ecosystems.
It turns out that earthworms - like zebra mussels, purple loosestrife and starlings - come from elsewhere.
"Any worm you see, baby," said Cindy Hale, a forest ecologist at the Natural Resources Research Institute in Duluth, Minn. "The grayish yellow, the ones that people call angleworms, leafworms, red wrigglers, nightcrawlers.
"They're all exotic, and they're all European."
There were no earthworms in the north woods before European settlement. If there ever were any, Ice Age glaciers probably took care of them.
"In fact, all of the deglaciated area essentially, anything that was glaciated, the earthworms were wiped out," said John Zawiskie, a geologist at the Cranbrook Institute of Science in Bloomfield Hills.
"Even after deglaciation, for thousands of years, the ground was frozen solid. We had tundra here in Oakland County."
There are native earthworms in North America, said Hale, but they live in the southern half of the continent where the ice sheets didn't reach. The worm that slithers out onto sidewalks after rains, that generations of kids have impaled on hooks in search of bluegills and perch, came here in the ballast of ships and the root balls of imported plants.
Unfortunately, the forest had already re-established itself by the time that happened, Zawiskie said.
"The return of forest way outpaced the migratory ability of native earthworms, so essentially for the last 10,000 years a lot of these northern hardwood forests evolved without any native earthworms," he said.
Worms are spreading, however, into new areas - and scientists know where to place the blame.
"Fishing bait is a huge factor in terms of the continued transport of earthworms across the landscape," Hale said.
She has found a high correlation between what she calls earthworm invasion fronts in Minnesota and areas that support fishing activity - such as lakes, streams and boat launches.
The problem is anglers dumping their bait.
"Sure, you've done it, haven't you?" Hale said. "So have I.
"But add up the numbers, and it gets pretty big quickly."
The situation is being taken seriously in Minnesota, where the state's Department of Natural Resources has a program with a poster urging anglers to "Contain Those Crawlers" by not dumping unused bait in the woods. The state wants anglers to instead dispose of worms in the trash.
Hale said ecologists have already noticed changes in the composition of the forest floor and among plant communities that evolved with organisms that decompose leaf litter much more slowly than do the ravenous earthworms.
"They remove the forest floor," Hale said. "In these sugar maple-dominated hardwood forests, under worm-free conditions, you would get the establishment of very thick spongy forest floor up to 10 centimeters or more which is composed of leaf litter."
That leaf litter provides nutrients for native plants and habitat for animals such as salamanders, small mammals and ground-nesting birds.
It's not that worms are necessarily bad, Hale said. It's just there are places where they don't belong.
"Everything you've ever heard about them being good in gardens and farming soils is true," she said.
"(But earthworms) can have quite deleterious effects in a native worm-free hardwood forest."