The state of Michigan is trying a new approach to stop the spread of foreign aquatic species in the Great Lakes – using a new system to clean ships’ ballast water. The Great Lakes Radio Consortium’s Quinn Klinefelter has more:
The state of Michigan is trying a new approach to stop the spread of foreign aquatic species in the Great Lakes – using a new system to clean ship’s ballast water. The Great Lakes Radio Consortium’s Quinn Klinefelter has more.
A generator deep in the bowels of the Canadian freighter “Federal Yukon” spits copper ion particles at a cargo hold filled with ballast water. The particles poison any creatures living in the water…a second process cleanses the ballast before it’s drained into the Detroit River. It’s a test designed to find – and hopefully eliminate – any species carried in the water that is NOT native to the Great Lakes. Michigan Lt. Governor Dick Posthumous warned the threat from foreign species like zebra mussels is very real.
“Like an uninvited house guest…they come in uninvited…they eat all your food…and then they leave the house all messed-up.”
Posthumous says the Great Lakes Governor’s Association will meet with Canadian leaders this fall in Chicago to try and find ways to prevent the spread of foreign aquatic species. For the Great Lakes Radio Consortium, I’m Quinn Klinefelter.
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:
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.
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:
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.
As the Great Lakes fishing season gets into full swing, an"exotic" ID card is being distributed to sport anglers all over theRegion. Its part of an research effort to track the spread of twoexotic species—the Round Goby and the Eurasian Ruffe (rough). The GreatLakes Radio Consortium’s David Hammond reports:
Controlling exotic species in the Great Lakes hasn’t been easy. Scientists have been unable to slow the spread of things like the zebra mussel. But they still have a chance to prevent other non-native species from infesting Great Lake waters. The Great Lakes Radio Consortium’s Steve Frenkel reports on a potential breakthrough:
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: