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:
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
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
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.