Rushing to Save Native Mussels

  • Michigan researchers are searching rivers and lakes for evidence of the native Purple Lilliput (pictured above). Photo by Doug Sweet.

In recent years, a great deal of attention has been focused on zebra mussels. They’re not native to the Great Lakes region and they’re pushing native mussels out of local lakes and streams. As the Great Lakes Radio Consortium’s Celeste Headlee reports, one scientist at a Detroit Aquarium has taken on the daunting task of trying to save a small, rare native mussel from disappearing in the state:

Transcript

In recent years, a great deal of attention has been focused on
zebra mussels. They’re not native to the Great Lakes region
and they’re pushing native mussels out of local lakes and streams.
As the Great Lakes Radio Consortium’s Celeste
Headlee reports, one scientist at a Detroit Aquarium has taken
on the daunting task of trying to save a small, rare native
mussel from disappearing in the state:


(ambient sound throughout – whenever Doug Sweet talks)


At a small pond near a highway, biologist Doug Sweet and his team put on waders and wet suits
and prepare to enter the sluggish brown water of Dawson’s Millpond Outlet in Pontiac. All
summer long, Sweet has made the trip from the Belle Isle Aquarium to this small pond looking
for a creature called the Purple Lilliput. These mussels, native to the Great Lakes area, have been
struggling to survive in Michigan, especially since the arrival of Zebra Mussels. Sweet’s made it
his mission to find out if there are any of these Lilliputs in Michigan still alive.


“I was very skeptical and didn’t know if we would find any live ones left because previous
surveyors were beginning to predict that they were gone. No one has found them for several
years.”


Zebra Mussels have been in the Clinton River for six or seven years. Zebras are very competitive
feeders. They strip the food out of the water before the native species can get it. Their presence
in domestic waters has had a catastrophic effect on many species. In fact, because of Zebra
Mussels and other factors like pollution, almost a third of North America’s freshwater mussels are
considered endangered or threatened with extinction.


Doug Sweet says Dawson’s Millpond Outlet is the last place to find Purple Lilliput mussels in
Michigan, and he’s afraid they will die out here, too.


“Looks like mostly all dead Purple Lilliputs. Yup.”


So far, Sweet and his team have found nine live Lilliputs. And that means there are probably
between 100 and 150 of them in that location. Though no one knows how long Purple Lilliputs
live, Sweet says other kinds of lilliput mussels live only about eight years.


“If the Purple Lilliputs are anything similar to that, then we’re running out of time because the
zebra mussels have been here for about six years now. And if they’re not reproducing, if there’s
too much competition, then we might be seeing the very last of the adult live Purple Lilliputs.”


When Sweet moved to the area, zebra mussels were starting to move into the Great Lakes region.
He’s a fish biologist, but he became so concerned about the plight of native mussels, he decided to
find out how they were faring. He contacted other biologists to ask what studies had been done.


Just a few years earlier, Oakland University Biology Professor Doug Hunter started looking for
the Purple Lilliput mussel in several lakes and streams around southeastern Michigan. During his
first few surveys, Hunter found more than 20 Lilliputs, but eventually he gave up hope and
assumed that the small creature was destined to die out in the state.


“Every year we went back after those first couple of fairly successful years, we got fewer and
fewer. The last time I went out there I think I got one or two. And I thought, “Well, this doesn’t
look good at all.” I wrote a report to the Wildlife Division in which I said, “I think this is an
imperiled population that may be on its way to local extinction.”


Doug Sweet picked up the research where Hunter left off and is now focusing his efforts on
trying to save the Purple Lilliput. Sweet says the number of lakes and streams in Michigan where
Zebra Mussels have taken hold is almost doubling every year. He says people should realize that
what they do with their boats affects an entire ecosystem.


“People are responsible for spreading the Zebra mussels all over the place. Everybody who has
Waverunners, boats, fishermen with bait buckets… they have to be conscientious that if they’re
fishing in one lake, you’ve got to clean your boat well before you transfer it to another lake or
stream.”


But even so, it may be too late for the Purple Lilliput. Sweet and his team snorkel through the
murky water, use glass bottom buckets, or dig their fingers into the black sediment, looking for
surviving buried mussels. Eventually, though, the hard work does pay off.


“A live one? Ooh, we think we have another live Purple Lilliput…
There we have it, another live one, ten, so this revises our population estimate right there, because
we found this in a quadrat excavation… This is excellent; it’s exciting. You know, who could say
that you’d get excited over a little critter like that.”


Later the same day, the team finds another live Purple Lilliput, a male, bringing the grand total up
to 11. Sweet hopes he can find a safe haven for the Lilliputs somewhere in southeastern
Michigan where the tiny population can slowly begin to recover. Doug Sweet is now finishing up
his fieldwork, and will soon begin studying his results for a report to the state.


For the Great Lakes Radio Consortium, I’m Celeste Headlee.

New Bubble Barrier to Repel Asian Carp?

The Asian carp is threatening to invade the Great Lakes. Right now there’s an electric barrier in the Chicago canal to stop the fish from getting into Lake Michigan, but a new study shows it’s not 100-percent effective. As the Great Lakes Radio Consortium’s Annie Macdowell reports, scientists are working on a second line of defense…bubbles:

Transcript

The Asian carp is threatening to invade the Great Lakes. Right now there’s an
electric barrier in the Chicago canal to stop the fish from getting into Lake
Michigan, but a new study shows it’s not 100% effective. As the Great Lakes
Radio Consortium’s Annie Macdowell reports, scientists are working on a second
line of defense – bubbles.


In a recent experiment by the Illinois Natural History Survey, a startled Asian
carp swam straight through an electric field like the one in the Chicago Canal.


The International Joint Commission is bringing specialists from Britain to build
an experimental acoustic bubble barrier and test it on the Asian carp. It works
like this: a pump filled with air and sound expels bubbles with sound trapped
inside.


Bill Moy of the Wisconsin Sea Grant says the process creates a nearly seamless
barrier.


“If you just project sound into the water, it’s not like a wall of sound. But by
entraining the sound in this bubble, you can actually create a wall of sound in
the water that’s much more uniform.”

Moy says the infrasound inside the bubbles is like an idling truck – you can feel it
more than you hear it.


The fish can’t find a break in the sound, so they turn around.


The International Joint Commission says if they decide to install the bubble
barrier, it won’t be until the spring.


For the Great Lakes Radio Consortium, I’m Annie MacDowell.

A Fish Eye View of the Lakes

  • The "Benthic Explorer" now sits on the bottom of Lake Superior and provides live pictures of its underwater world. Photo by Chris Julin.

If you’ve ever been curious about what goes on at the bottom of the world’s largest lake, you can take a look for yourself – and you don’t even have to get wet. A device called the “fishcam” is sitting under 35 feet of water in Lake Superior and it’s now sending pictures to the Internet. Researchers say it’s the only permanently mounted underwater camera in the world sending live images back to shore. The pictures are fun to look at, but researchers say they’re also useful to biologists who study underwater life in the Great Lakes. The Great Lakes Radio Consortium’s Chris Julin has the story:

Transcript

If you’ve ever been curious about what goes on at the bottom of the world’s largest lake, you can take a look for yourself — and you don’t even have to get wet. A device called the “fish cam” is sitting under 35-feet of water in Lake Superior and it’s now sending pictures to the Internet. Researchers say it’s the only permanently mounted underwater camera in the world sending live images back to shore. The pictures are fun to look at, but researchers say they’re also useful to biologists who study underwater life in the Great Lakes.


The Great Lakes Radio Consortium’s Chris Julin has the story.


A team of researchers put the camera underwater more than a year ago. It sits on the lake bottom, several miles from Duluth. The researchers have watched pictures from the “fish cam” for months, but now, anyone with a computer hooked to the Internet can get a scuba diver’s view of the bottom of Lake Superior. The research team recently gathered at the Great Lakes Aquarium in Duluth to unveil the “fish cam” website. Fish expert Greg Bambenek has had the fish cam hooked-up to the computer at his house, but at the aquarium, he watched the fish cam on the screen of a laptop.


“That’s streaming out on the web right now. It’s updated every ten seconds. The fish there are mullet. At night, we have a micro-cam that brings the zooplankton into close focus, and at times you’ll see the mullet eating the zooplankton.”


Those zooplanktons are tiny animals called “water fleas.” They’re fractions of an inch long –far too small to show up through the fish cam’s standard lens. But Bambanek says it’s a different story at night, when the fish cam switches to a magnifying lens, and the computer screen comes alive with little critters.


“Leptodora is the large one. Then you’ll see little copepods that kind of look like Pokemon creatures with the antennas coming off their head, and they’re smaller. They’re only a couple millimeters, so you wouldn’t be able to see them if you were diving in the water.”


The people gathered to see the fish cam’s first Internet images had to settle for a murky picture. A strong northeast wind was blowing in off the lake, kicking up big waves, and stirring up the bottom. The researchers say big waves make for blurry pictures. Even so, lots of fish were visible in the frame. The fish might be crowding in because researchers are releasing fish scent through a special tube attached t the camera. But photographer Doug Hajicek says it’s surprising how many fish swim past even without the fish scent. Hajicek designed and built the underwater camera, and he’s been watching a private feed from the fish cam for months.


“This lake is extremely alive. There is a food chain that is so delicate and tiny. Everybody thinks of Lake Superior as just a sterile body of water, and we’re hoping to change that.”


Some of the fish that swim into view are called ruffe, a non-native species that’s invading the Great Lakes. Researcher Greg Bambenek says it is surprising see so many ruffe here, six miles from Duluth. He says biologists believed ruffe stayed closer to harbors. Bambenek says that’s just one example of the valuable information about life in the Great Lakes that scientists can get from the fish cam.


“We can take freeze-frame, count the number of zooplankton, count the number of fish, and also look at it over time, and also see what does a northeaster do? What do the fish do? Do they leave? Do they come back? What does water temperature do? We have a temperature sensor down there. We also have a hydrophone so we can hear what’s going on underneath the water. So, it is a research tool.”


Bambenek says the research team learned a lot during the year it took to get the camera up and running on the Internet. He says the team is planning to put another camera in Lake Superior, farther from shore, and hopes to put a third camera somewhere on the floor of the ocean.


You can see images from the Lake Superior fish cam at Duluth.com/fishcam.


For the Great Lakes Radio Consortium, this is Chris Julin in Duluth.

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