Radio Waves Zap Zebra Mussels

Researchers say low frequency radio waves may be a more effective way of controlling zebra mussels. The Great Lakes Radio Consortium’s Tom Scheck has the story:

Transcript

Researchers say low frequency radio waves may be a more effective way of controlling zebra mussels. The Great Lakes Radio Consortium’s Tom Scheck reports.

Zebra mussels have caused millions of dollars of damage to power plants, boats and intake pipes. They’ve also seriously hurt native species in the Great Lakes and other inland waterways. Purdue University chemistry professor Matthew Ryan says he may have found a way to control the zebra mussels without harming fish or other aquatic wildlife. In the laboratory, he says low frequency electromagnetic radio waves were found to cause the zebra mussels to lose critical minerals at a much faster rate than they can acquire them.


“It ultimately kills them. There’s a stress response after a day or so. They stop feeding and begin to close their shells and after about 19 days about 50 percent of the mussels in a given population will be dead.”


Ryan says native fish and clams were not harmed when exposed to the same technique. If it’s proven effective in the wild, he says electrical barriers could block mussels from infesting other lakes and streams. For the Great Lake Radio Consortium, I’m Tom Scheck in Saint Paul.

Native Lake Species Fighting Back

  • Alewives washed up on Lake Michigan shores after the invaders' populations exploded, then crashed. Researchers have a difficult time predicting how invasive species will affect the balance of nature in the Great Lakes.

Ever since the Great Lakes were opened to shipping, exotic species of aquatic animals have invaded the lakes. Nearly always it’s been bad news for the region’s native fish and wildlife. The Great Lakes Radio Consortium’s Lester Graham reports on the latest effects of the invaders:

Transcript

Ever since the Great Lakes were opened to shipping, exotic species of aquatic animals have invaded the lakes. Nearly always it’s been bad news for the region’s native fish and wildlife. The Great Lakes Radio Consortium’s Lester Graham reports on the latest effects of the invaders.


Some of the exotic species that have caused major problems in the Great
Lakes have been around since the 1940’s and ’50s. For example, the sea lamprey found its way into the lakes through manmade channels. It’s a parasite that attacks lake trout and other large game fish. It devastated the lake trout fisheries. Only recently have efforts gotten the lamprey under control. It’s still out there, but it’s not decimating the lake trout population as it once was.


More recently, a big concern has been the zebra mussel. It hitchhiked its way to the Great Lakes in the ballast water of cargo ships. In the last couple of decades the zebra mussel has caused major changes in all the lakes except for Superior where it seems limited to the shallow and warmer bays.


David Jude is a researcher with the University of Michigan’s Center for
Great Lakes and Aquatic Sciences. He says the huge numbers of zebra mussels siphon through lake water like a giant network of filters. There are so many of them that water in the lakes is actually clearer.


“I think people tend to hear about the water clarity increases. ‘Ah, the water’s clearer,’ you know, ‘That’s great!’ But it’s not great, because there’s a lot of things going on in the water column.”


Things such as, algae converting the sun’s energy into more phytoplankton.
Small fish and tiny invertebrate animals called zooplankton eat the phytoplankton and then they become food for fish. But, the zebra mussels filter out a lot of the phytoplankton, stealing food from the native zooplankton.


David Jude says a couple of other invaders are also causing havoc at the base of the food chain in the Great Lakes. Instead of eating just the green phytoplankton, zooplankton invaders from the Black and Caspian Seas also eat their North American cousins.


“These are predators. And they feed on the zooplankton, our native zooplankton that is out there already. So, not only do we have the impact of zebra mussels removing algae which is a food for these zooplankton, now we’ve got two predators that have been introduced and both of those will eat zooplankton which would have been food for fish to eat.”


Besides the zooplankton floating around in the water column, a major food source for fish is in the sediment at the bottom of the lakes, and it’s disappearing. James Kitchell is with the University of Wisconsin – Madison. He says many different kinds of fish depend on a little creature called diaporeia, which have become scarce in many areas.


“It appears to correlate in general with an increases in zebra mussels. So, there’s the prospect that diaporeia is literally starving to death as a consequence of zebra mussels eating the available food, but when you look at the diaporeia, they appear to be healthy. They’re not skinny and look to be starving. So that doesn’t explain it.”


It’s a big concern because a lot of fish that anglers like, such as yellow perch, depend on diaporeia for food.


Besides the zebra mussels and the two zooplankton predators, a fourth invader is causing problems. Populations of the round goby, an ugly, aggressive feeding little fish from Eastern Europe, have exploded in the Great Lakes. The round goby scours the bottom, eating the eggs and larvae of native fish. The University of Michigan’s David Jude says as big of a problem as the invasive fish has been over the last several years. The round goby’s future might soon be curtailed a bit.


“We did SCUBA dives in Lake Erie, for example, we’d turn over rocks. Round gobys would tear out from under the rocks and we’d have small mouth bass following us around and they would ignore the round gobys. They didn’t know how to catch a round goby. But, because there’s so many round gobys now, they had to learn how to eat them or die. So, the predators are definitely learning how to eat round gobys.”


Other native fish are beginning to eat the exotics. The silver chub, which once nearly disappeared from the Great Lakes, is making a bit of a comeback feasting on zebra mussels. With each invader, the lakes ecosystems go through upheaval, and then find a new balance. But make no mistake. It’s a different balance. Nicholas Mandrak is a researcher at Youngstown State University. He says exotic species invading the Great Lakes will mean continued changes, and for people who fish the lakes, not many of the changes will be good.


“You’re not going to be able to catch as many species that you’re used to catching. You know, the native species are going to decline. The walleye are going to decline. So, I think the bottom line is the recreational and commercial fisheries are going to change in a manner that is negative to most people.”


Researchers, though, have learned to be careful about predicting how invasive species will affect the lakes. They’re often surprised by the intricacies of the food web and the ecosystems that support it. Throwing an exotic invader into the mix makes it that much more unpredictable, and it will likely get worse. Mandrak says they’ve been studying how global warming might affect the lakes. One scenario suggests 30 to 40 new exotic species from the South will make their way through manmade canals as temperatures rise. For the biologists, it’s a worrisome concept. For the Great Lakes Radio Consortium, this is Lester Graham.

NATIVE LAKE SPECIES FIGHTING BACK (Short Version)

It appears that fish native to the Great Lakes are beginning to prey on some of the alien species that have invaded the lakes. The Great Lakes Radio Consortium’s Lester Graham reports:

Transcript

It appears that fish native to the Great Lakes are beginning to prey on some of the alien species that have invaded the lakes. The Great Lakes Radio Consortium’s Lester Graham reports.


Aquatic Species from Europe and elsewhere have hitchhiked to the Great Lakes in the ballasts of cargo ships for many years. A lot of them have upset the natural ecosystems of the lakes. Lately, though, some native fish are taking advantage of the invaders. Nicholas Mandrak is a researcher at Youngstown State University. He says a Great Lakes minnow that was once thought to have died out has recently re-emerged.


“And they’re eating zebra mussels. So, it looks like the increase
in silver chub is related to zebra mussels, so we finally found a native
fish that is benefiting from the zebra mussel.”


Other researchers say small mouth bass are beginning to prey on another invasive species, the round goby, which eats the eggs and larvae of fish native to the Great Lakes. The researchers say the benefits don’t outweigh the negative affects on native species. But it evens the score a little. For the Great Lakes Radio Consortium, this is Lester Graham.

City Ignites Green Space

Many cities create parks to try to incorporate green space into theirurban landscapes. But maintaining them can be expensive and laborintensive. Now, one city has created a unique solution–addingnaturalbeauty while saving money. The Great Lakes Radio Consortium’s Tasya Rosenfeld has the story:

Farm Management Mimics the Past

Increasing numbers of American farmers are going "back to the
future" – moving away from the high-investment, high-energy farming
methods of the last fifty years, and experimenting with modern versions
of more traditional techniques. The Great Lakes Radio Consortium’s
Stephanie Hemphill reports:

Beetle Controls Purple Loosestife

A European plant called purple loosestrife is increasingly making
itself at home near lakes, wetlands, and meadows throughout the Great
Lakes region. That’s bad news for native plants that are pushed out by
the aggressive newcomer. But help could be on the way. The Great
Lakes Radio Consortium’s Tracy Samilton reports on a program to
introduce a loosestrife-munching beetle:

The Business of Fish Management

  • Similar scenes can be found up and down the eastern shore of Lake Michigan.

Now that summer’s officially here, beaches around the region are packed with
tourists and locals. But this year many beaches have been plagued with
unwanted visitors: tens of thousands of dead fish in the water and on the
sand. It’s a revolting sight-and smell – but in fact, the fish play an
important role in the lakes…and present an ongoing management challenge to
biologists. The Great Lakes Radio Consortium’s Wendy Nelson explains:

The Comeback of the Wood Frog

Scientists are concerned about a world-wide decline in amphibian
populations. But one scientist has been bringing a frog back to its
native habitat. The Great Lakes Radio Consortium’s Lester Graham reports
the Wood frog is once again thriving in an area where it was pushed out
more than 75 years ago:

Seed Industry Growing in Foreign Markets

The global marketplace is growing, with many industries enjoying theadvantages of free trade agreements that give them easier access toforeign consumers. But seed businesses still face tight regulationswhen it comes to crossing borders, and some in the industry say therestrictions should be loosened up. But if that happens, there may bean environmental price to pay. The Great Lakes Radio Consortium’s WendyNelson reports:

Restoration Practices Generating Controversy

Years ago, forest preserves were established in many American cities toprotect valuable natural areas from urban development. But over theyears, the health of those preserves has declined. Conservationists arenow trying to repair the damage by actively restoring those naturalareas. But now, some of their techniques are being questioned. TheGreat Lakes Radio Consortium’s Steve Frenkel reports: