June 1, 1988, the day everything changed for the Great Lakes, was
sunny, hot and mostly calm — perfect weather for the young researchers
from the University of Windsor who were hunting for critters crawling
across the bottom of Lake St. Clair.
Sonya Santavy was a freshly graduated biologist aboard the research
boat as its whining outboard pushed it toward the middle of the lake
that straddles the U.S. and Canadian border. On a map, Lake St. Clair
looks like a 24-mile-wide aneurysm in the river system east of Detroit
that connects Lake Huron to Lake Erie. Water pools in it and then churns
through as the outflows from Lakes Superior, Michigan and Huron swirl
down into Erie, then continue flowing east over Niagara Falls into Lake
Ontario, and finally out the St. Lawrence River to the Atlantic Ocean.
David Kenyon, Michigan DNR
Researcher Sonya Santavy, who discovered Zebra Mussels during a survey in Lake St Clair in 1988.
The water moves so fast through Lake St. Clair because the lake is as
shallow as a swimming pool in most places, except for an approximately
30-foot-deep navigation channel down its middle. The government
carved that pathway long ago to allow freighters to sail as far inland as Milwaukee and Duluth.
When water levels are low or sediment is high, the channel isn't deep
enough and sometimes ships have to lighten their loads to squeeze
through. That means dumping water from ship-steadying ballast tanks —
water taken onboard outside the Great Lakes, water that too often and
for too long swarmed with exotic life from ports around the globe.
As the three young researchers were drifting over a rocky-bottomed
portion of Lake St. Clair on that steamy Wednesday morning, Santavy
decided to drop her sampling scoop into the cobble below. She was
hunting for muck-loving worms but figured she'd take a poke into the
rocks because, well, to this day, she still doesn't know.
"I can't even explain why it popped into my head," Santavy says. "I
thought — if we get nothing, we get nothing, and I'll just mark it off
that this is not an area to sample."
Up came a wormless scoop of stones, the smallest of which were pebbles not much bigger than her fingertips.
But there was something odd about two of these tinier stones. They were stuck together.
She tried to muscle them apart but she couldn't.
Then she realized that one of them was alive.
Slamming shut the doors
A watershed moment has arrived for the Great Lakes.
After decades of regulatory paralysis, a federal judge has forced the
U.S. Environmental Protection Agency to begin requiring overseas ships
to decontaminate their ballast water before discharging it into the five
lakes that together span a surface area the size of the United Kingdom.
The St. Lawrence Seaway, which was completed in 1959,
is an intricate system of locks, dams and canals that allows ocean
freighters to sail up the roaring St. Lawrence River, around Niagara
Falls and into the once-isolated upper Great Lakes. The Seaway opened
Great Lakes ports to not only foreign cargoes, but also to dozens of
unwanted species.
Journal Sentinel
Despite their vastness, for thousands of years the inland seas above
Niagara Falls were as isolated from the outside world as a Northwoods
Wisconsin pond. That all changed in 1959. The U.S. and Canadian
governments obliterated the lake's natural barrier to invasive fish,
plants, viruses and mollusks with the construction of the St. Lawrence
Seaway, a system of channels, locks and dams that opened the door for
ocean freighters to sail up the once-wild St. Lawrence River, around
Niagara Falls and into the heart of the continent.
Small boats had access to the lakes since the 1800s thanks to
relatively tiny man-made navigation channels stretching in from the East
Coast and a canal at Chicago that artificially linked Lake Michigan to
the Mississippi River basin.
But the consequences of opening a nautical freeway into the Great
Lakes for globe-roaming freighters proved disastrous — at least 56
non-native organisms have since been discovered in the lakes, and the
majority arrived as stowaways in freighter ballast tanks.
These invaders have decimated native fish populations and rewired the
way energy flows through the world's largest freshwater system,
sparking an explosion in seaweed growth that rots in reeking pockets
along thousands of miles of shoreline. The foreign organisms are
implicated in botulism outbreaks that have suffocated tens of thousands
of birds on the eastern shore of Lake Michigan. They are among the
culprits responsible for toxic algae blooms on Lake Erie that threaten
public water supplies.
The hope is the new ballast discharge regulations will shut the door to new invasions.
The reality: The Environmental Protection Agency has already acknowledged they are not stringent enough to do that job.
The agency blames a lack of technology to adequately disinfect
ballast tanks. Critics blame a lack of resolve in getting tough with the
relatively tiny overseas shipping industry that has done so much damage
to this singularly important natural resource; an average of fewer than
two such ships visit the lakes each day during the Seaway's nine-month,
ice-free shipping season.
"We can do much better," says biologist Gary Fahnenstiel, who spent
his career chronicling the ecological unraveling of Lake Michigan for
the National Oceanic and Atmospheric Administration. "If we really care
about the lakes."
Solving the Seaway ballast problem isn't just about the Great Lakes,
because the invaders have a history of making their way into waters
across the continent. Out West, where Great Lakes invasive mussels are
spreading as fast as boats are towed from lake to lake, states now have
laws to throw people in jail and fine them thousands of dollars for
transporting the same species Seaway freighters dumped on the continent
with impunity.
Great Lakes advocates predict the bubbling frustration out West over
the Seaway's role in their troubles will erupt if — or when — Seaway
ships unleash yet another invader.
"The industry has had this grace period to find solutions," says
Phyllis Green, superintendent of Isle Royale National Park in Lake
Superior. "The grace period they have been given will hit the fan when
they find the next one."
The pressure is mounting inside the Great Lakes basin as well,
because even as the EPA leaves this front door to the Great Lakes
cracked open, the U.S. Army Corps of Engineers is
under fire from Congress to shut the back door
— the Chicago canal system that is the prime pathway for Asian carp to
invade the lakes. Rebuilding the natural divide between Lake Michigan
and the Mississippi River basin is a project that likely wouldtake years
and cost billions of dollars.
But it begs the question: Why spend all this money to close the back
door if we aren't going to shut and seal the front door as well?
Building a barrier to protect the upper Great Lakes from Seaway
invaders would actually be simpler than restoring the natural watershed
divide at Chicago. In fact, such a barrier already exists.
It's called Niagara Falls.
The St. Lawrence River was once wild and
impassable to ships, which Canadian and U.S. governments tried to change
with the construction of the St. Lawrence Seaway. This map – which
explores the history of the St. Lawrence Seaway and its role in the
introduction of invasive species – was completed by Marquette University
Diederich College of Communication student Erin Caughey as part of the
O'Brien Fellowship in Public Service Journalism.
'It's crazy to go on ... studying this'
Santavy showed a fellow scientist aboard the research boat her living
"stone" with wavy bands that allowed it to blend into the rocks below.
Both knew it was some kind of clam or mussel, but the dime-sized mollusk
looked like nothing Santavy's colleague had seen before. This was
remarkable. He was a graduate student whose job was to study freshwater
clams of North America.
They motored the boat to shore and brought the curious shell back to
the university, where the biology professors also were flummoxed.
Quagga and zebra mussels are native to the Caspian
and Black Sea regions of eastern Europe. Eventually, the mussels
colonized rivers and lakes across western Europe thanks to an extensive
network of canals and locks. By the 1980s, the mussels hitchhiked their
way around the globe to the Great Lakes via the St. Lawrence Seaway.
Journal Sentinel
The specimen was driven a few hours over to the University of Guelph
outside Toronto, where an international mussel expert recognized it
immediately as
Dreissena polymorpha, the zebra mussel. This was
not good news. The species, native to the Caspian and Black Sea regions,
was famous on the other side of the Atlantic for its ability to glue
itself to any hard surface in wickedly sharp clusters that bloody
boaters' hands and swimmers' feet, plug pipes, foul boat bottoms and
suck the plankton — the life — out of the waters it invades.
The mussels had already colonized rivers and lakes across Western
Europe thanks to an extensive network of canals and locks that, like
North America's Seaway, had allowed biological trouble to course through
a continent like viruses in a bloodstream. Hungary succumbed to an
infestation in 1794, London in 1824. Rotterdam fell in 1827 followed by
Hamburg in 1830 and Copenhagen in 1840. The ecological menace had moved
on to Switzerland, Finland, Ireland and Italy by the 1970s.
Then in 1988 this specimen turned up in Lake St. Clair, some 3,000
miles from its closest known colony. A zebra mussel has something of a
"foot" that enables it to drag itself across a lake bottom, but the
fastest adult zebra mussel can only trundle along at a rate of about 14
inches per hour.
Scientists knew the only plausible way Santavy's mussel could have
made the trip across the Atlantic and into the Great Lakes was in the
friendly confines of a freighter ballast tank.
The discovery of the single shell might have meant little initially
to the young researchers who found it, but seasoned ecologists knew the
doom it foretold, like radiologists spotting a telltale speck on an
X-ray.
Distressing as the news was, nobody should have been surprised.
As early as the late 1800s, naturalists had recognized the zebra
mussel as an invasive species juggernaut, according to James Carlton, a
Williams College biologist who has tracked historical warnings of mussel
troubles.
U.S. Geological Survey
Native to
Black and Caspian seas.
Threat to Great Lakes
The mussels reproduce at extreme rates, coating boat bottoms, marina
equipment and beaches. Within months of their discovery, there were
billions in the Great Lakes basin. Communities and companies have spent
billions of dollars to clear them out of industrial and utility intake
pipes.
Discovered
Lake St. Clair, 1988.
How widespread
Now established in all the Great Lakes and in major rivers in the
eastern United States. They have been transported across the country
when stuck on recreational boats.
"The Dreissena is perhaps better fitted for dissemination by man and
subsequent establishment than any other fresh-water shell," English
zoologist Harry Wallace Kew wrote in 1893. "Tenacity of life, unusually
rapid propagation, the faculty of becoming attached by string byssus to
extraneous substances, and the power of adapting itself to strange and
altogether artificial surroundings have combined to make it one of the
most successful molluscan colonists in the world."
A second warning came in 1921 from Charles Johnson, curator of the Boston Society of Natural History.
"The possibility of ... the zebra mussel being introduced (to the
United States) is very great. There is entirely too much reckless
dumping of aquaria into our ponds and streams. A number of foreign
freshwater shells, etc., have been introduced this way. Why not the
mussel?"
Another alarm came in 1964, five years after the opening of the St. Lawrence Seaway.
"There is the real possibility that
Dreissena polymorpha will
eventually become established in the North American continent despite
all efforts to prevent introduction of exotic species," cautioned
biologist Ralph Sinclair.
A final alarm came in 1981 when a group of scientists took the time
to see what was lurking in the ballast tanks of foreign freighters bound
for the Great Lakes. They found the ships were basically floating
ecosystems, teeming with life sucked up from ports around the globe.
The researchers specifically mentioned zebra mussels as a primary threat to invade.
The U.S. and Canadian governments did nothing in response.
Ballast water invasions aren’t just a North American problem.
A jellyfish-like creature native to the U.S. Atlantic Coast has made a
mess of the Black Sea — the original home of the quagga mussel, one of
the nastiest invaders to hit the Great Lakes.
The comb jelly, formally known as
Mnemiopsis leidyi, is a
baseball-sized predator that was likely picked up by a freighter sailing
into the Black Sea from the United States in the early 1980s.
Its impact on the Black Sea was immediate and profound, decimating
the region’s nearly quarter-billion-dollar annual anchovy fishery in
less than a decade.
By 1990, according to the University of Wisconsin, there were an
estimated 1 billion tons of the comb jelly swimming the Black Sea —
roughly equal to the weight of all the fish caught in the world’s
oceans that year.
Numbers have since diminished, thanks to the arrival in the late 1990s of yet another exotic species — the
Beroe ovata,
a natural predator of the Black Sea's invasive comb jelly. While the
stocks of anchovies have since recovered somewhat, other fish species
never rebounded from the initial comb jelly invasion.
The comb jelly has now spread across Europe, including the
Mediterranean and Caspian Seas, according to the National Environmental
Coalition on Invasive Species.
Its success in the Black Sea has resulted in it being known among
invasive species researchers as North America’s revenge for the zebra
mussel.
— Dan Egan
The next year, in 1982, overseas ships were blamed for bringing into
the lakes the spiny water flea that has ravaged native zooplankton and
the little fish that depend upon them. The year after that, overseas
ships were identified as the culprit for the arrival an exotic tubificid
worm. In 1986, a fish called the Eurasian ruffe was discovered in Lake
Superior.
Two years after that, in 1988, news of Santavy's zebra mussel find
reached the public with a front-page story in the Windsor Star. It
declared that a novel "zebra clam" might cost the region millions of
dollars because of its ability to clog industrial water intake pipes.
"This guy hitchhiked inside a ballast tank," Paul Hebert, director of
the University of Windsor lab where Santavy worked, told the reporter.
"It's crazy to go on studying and studying this — we have to do
something. We're getting new species in the lake all the time."
Santavy found just one mussel. Everybody knew there had to be more. They just didn't know how many.
A tiny foe, a giant mess
Tom Nalepa, then an ecologist with the National Oceanic and
Atmospheric Administration, remembers making the three-hour drive from
his office in Ann Arbor, Mich., to London, Ontario, in March 1989 to
meet with 11 other scientists about the latest Great Lakes invader. It
was already spreading faster than the North American scientists' ability
to read up about it.
The researchers that day, in fact, couldn't even agree whether to
call it a clam or a mussel. Conference host Ron Griffiths of the Ontario
Ministry of Natural Resources took the diplomatic tack of referring to
it as the "zebra mussel clam." The problem was there was almost no North
American literature on the life cycle of the zebra mussel because —
until then — there had been no North American zebra mussels. Scientists
were gleaning what they could from research papers written in Russian,
Polish and Danish just to figure out things like its preferred habitat,
its temperature tolerance and its reproduction rate.
"A lot of the literature I've read is in another language, and I can
only go as far as the abstract," Gerry Mackie, a mussel expert from the
University of Guelph, confessed at the outset of the conference, a video
tape of which was provided to the Milwaukee Journal Sentinel.
The researchers turned on a carousel slide projector to look at how
far the zebras had come since Santavy dropped her scoop to the bottom of
Lake St. Clair just 10 months earlier. The room got quiet as the wheel
stopped with a double clunk on each new image.
■ An engine block found on the bottom of Lake St. Clair so encrusted with zebra mussels its piston holes were plugged.
■ A Coast Guard buoy hauled in from Lake Erie coated with shells to the point that it was unrecognizable.
■ A Great Lakes beach littered with bleached mussel shells lying open on their sides, like so many little mouths.
Then Griffiths turned on a videotape of a mussel-smothered ferry
wharf on the Canadian side of Lake Erie. There were so many shells
nobody tried to calculate how densely they smothered the pier's pilings
and steel. It would have been like counting grains of sand on a beach.
"Man," ecologist Nalepa thought as he sat with his colleagues around
tables littered with coffee cups and jars of zebra mussel specimens.
"Nothing is going to be the same. Nothing."
There was some talk that day about how the mussels might affect
native fisheries, but the scientists mostly worried about what the
mollusks could do to the region's industries, given their ability to gum
up pipes.
Origin
The quagga mussel is native to the Black Sea basin. It was first identified in North America in 1991.
Identification
Quaggas, which can sometimes grow bigger than an inch, are slightly
larger than their more famous cousin, the zebra mussel. It often takes
an expert to distinguish between the two species, but the quagga is an
entirely different animal when it comes to the mussels' respective
impacts on the Great Lakes.
Physical tolerances
Unlike zebra mussels, quaggas can thrive at depths well below 100 feet
and don't require hard surfaces to grow upon. Quaggas can also tolerate
much colder water, enabling them to feast on plankton year-round, which
has a profound impact on food availability for Great Lakes fish.
Reproduction
Females can produce about 1 million eggs per year, though only about 1%
to 3% of those survive to adulthood. This still makes for a lot of
mussels; untold trillions now blanket the bottom of the Great Lakes, in
some places at densities greater than 35,000 per square meter.
Feeding
Most people never see quaggas in action, but under water their clasped
shells open and a filtering tube emerges to siphon free-floating
plankton from the water. Each adult can filter about a liter of water
per day.
Zebra
mussels were once the dominant invasive mussel species in Lake
Michigan, but they virtually have been eliminated by their close
relative, the quagga mussel. In just a decade, the filter-feeding
mollusks literally have turned life upside down in Lake Michigan by
sucking to the bottom much of the plankton that sustained a healthy
commercial fishery.
Tom Nalepa, National Oceanic and Atmospheric Administration
A biologist with a Michigan power utility showed another video that
revealed the zebra mussels were beginning to gather in golf ball-sized
clusters on the water intake pipes at the massive Monroe Power Plant on
the western shore of Lake Erie. He predicted that, unchecked, the
mussels could cost the plant hundreds of thousands of dollars. Per day.
Griffiths, the conference host, told the group one of his biggest
challenges was explaining to the public that the wave of shells washing
across the region would not stay confined to the Great Lakes.
"Everybody on reservoirs or inland lakes, they just pass it off and
they keep laughing at these guys because they're so small," he said.
"Right now, there is no way anyone believes that a critter that small
can cause any kind of problem."
By the end of the year, zebra mussels had turned up all across the
Great Lakes, west to Duluth, south to Chicago, east to the St. Lawrence
River below Lake Ontario.
A colony was also found in the Chicago Sanitary and Ship Canal. That
meant the mussels were already making their way beyond the Great Lakes.
Water samples showed zebra mussels' microscopic young, called veligers,
were drifting in the current of the Chicago canal, which feeds the
Illinois River, which in turn nourishes the Mississippi. It didn't take
long before researchers at a sampling site were counting veligers
coursing down a waterway in the heart of the continent at a rate of 70
million per second.
But the most ominous mussel development of 1989 made no headlines.
Researchers on Lake Erie found what appeared at first to be a slightly
different version of the zebra mussel.
It was, they would learn two years later, the quagga mussel.
Zebra mussels proved to be a pox on industries that depend on Great
Lakes water, costing them billions of dollars over the last quarter
century to keep pipes open and water flowing through everything from
kitchen faucets to nuclear power plants.
Yet the ecological damage wrought by zebra mussels is minor in
comparison to their cousin the quagga. Zebra mussels have an impact on
only a sliver of the overall ecology of the lakes because they are
restricted to relatively shallow waters rimming the shorelines and need a
hard surface to live on.
Quaggas aren't shackled to the shorelines. Unlike zebra mussels,
which typically aren't found at depths beyond 60 feet, quaggas have been
plucked from waters hundreds of feet deep and can thrive even in soft
sediments. They can blanket almost the entire lake bottom. Zebras also
feed only during the warmer months, while quaggas filter nutrients out
of the water year-round.
Three years after quagga mussels were discovered in Lake Michigan,
zebra mussels still made up more than 98% of the lake's invasive mussel
population. By 2005, that relationship had flipped, with quaggas making
up 97.7% of the invasive mussel population.
Scientists knew instantly back in 1989 that the arrival of zebra mussels was a game changer for the Great Lakes as we knew them.
Quaggas made it game over.
"Everybody used to say, 'Oh no! Zebra mussels!'" University of
Wisconsin-Milwaukee biologist Russell Cuhel said after the quaggas
mysteriously surged. "Well, zebras don't hold a candle to what these
guys are going to do."
Hard to fathom
The public can comprehend the devastation of a catastrophic wildfire
that torches vast stands of trees, leaves a scorched forest floor
littered with wildlife carcasses and turns dancing streams into oozes of
mud and ash. But forests grow back. The quagga mussel devastation of
Lake Michigan is so profound it is hard to fathom.
"People look at the lake and don't think of it as having a geography.
It's just a flat surface from above — and from there it looks pretty
much the same as it did 30 years ago," UWM ecologist Harvey Bootsma said
last fall as he prepared to scuba dive into the bizarre new web of life
off Shorewood's Atwater Beach.
"But under water, everything has changed."
Harvey Bootsma, a University of
Wisconsin-Milwaukee ecologist, examines mussel and algae cover near
Atwater Beach in Shorewood. His team dives every two weeks to examine
what is happening on the lake's bottom due to invasive species.
The mollusks now stretch across the bottom of Lake Michigan almost
from shore to shore, piling on top of one another like a gnarly, endless
plate of coral, clustering at densities exceeding 35,000 per square
meter.
People might still think of Lake Michigan as an inland sea full of
fish. It's now more accurate to think of it as an exotic mussel farm.
The lake's quagga mass was estimated in one recent year to be about 7
times greater than the schools of prey fish that sustain the lake's
struggling salmon and trout.
"People really don't grasp what has happened here," Bootsma explained
as he squeezed into a rubber dry suit aboard a university-owned boat
and prepared to dive to a research site a half mile off Atwater Beach.
He strapped on a scuba tank, climbed over the back of the boat,
dropped into the frothing surf and plunged to the lake bottom 30 feet
below. He might as well have landed on another continent, because under
the surface Lake Michigan bears little resemblance to the freshwater
wonder that left early European explorers awestruck by its abundance of
lake trout, whitefish, sturgeon, herring and perch.
Great Lakes Aquatic Nonindigenous Species Information System
Native to
Black Sea, Caspian Sea, Sea of Azov and their tributaries in eastern Europe and the Middle East.
Threat to Great Lakes
Primarily feeds off fish eggs, which has caused a large drop in mottled
sculpin and smallmouth bass populations. When the gobies feed on zebra
and quagga mussels, they pass along toxins ingested by the mussels,
which causes more damage up the food chain.
Discovered
Lake St. Clair, 1990.
How widespread
Established in all the Great Lakes and many of their tributaries.
Highest populations have been found in Lake Erie, Lake Ontario and Lake
Michigan.
Invasive, mussel-gobbling round gobies are now the dominant fish
species in the waters off Milwaukee. The invaders from the Black and
Caspian seas that also arrived aboard overseas freighters thrive amid a
shin-high forest of a plant called Cladophora, which needs three things
to thrive: sunlight, nutrients, and a hard surface.
The mussels provide all three. Their plankton-stripping ability has
dramatically increased the depths to which sunlight can penetrate. Their
shells provide a surface on which the seaweed can grow and the mussels'
phosphorus-rich excrement fuels the plant's growth. The result is an
endless forest of brilliantly green, hair-like tendrils swaying in the
current, invisible to anyone on shore — until it inevitably dies and
washes up on the beach.
Bootsma finds the changes professionally interesting, but personally
distressing. The 53-year-old attributes his career to summer days he
spent as a child on Georgian Bay in northern Lake Huron, fishing for
bass and perch and snorkeling to the rocky bottom to capture crayfish.
He still remembers the pit he'd feel in his stomach when his family
would pack up from their camping trips to Killbear Provincial Park and
drive three hours south to their home in the steel mill city of
Hamilton, Ontario.
"We'd go up there for the holidays and I'd be out in the sun and on
the water every day all day, and I remember every time when it was the
day to go home, I'd be close to tears," he said. "I still remember
telling myself that when I grow up I'm going to get a job that will keep
me on these lakes all the time."
Outside his office window at UWM's School of Freshwater Sciences are
the grain elevators and coal piles that define Milwaukee's inner harbor.
That harbor is connected to Lake Michigan, which is connected to Lake
Huron, which connects to Georgian Bay. They all have different names,
but in actuality they are the same lake, and the largest lake by surface
area on the globe.
It is no longer the lake Bootsma fell in love with. He's known this
in his head for years because of his almost weekly trips out to his
research stations off Shorewood. But the changes really didn't hit him
personally until he traveled back to Killbear Park a few years ago with
his own children.
"I snorkeled some of the same areas that I did as a kid. I still saw
some bass and that made me happy," he said. "But it was just devastating
to see all the mussels and the gobies."
What's even more distressing for him is the idea that his children don't even know what they're missing.
Ecologists call it the "shifting baseline phenomenon" — a fancy way
of saying that kids are getting cheated out of the lakes their moms and
dads loved.
"It's just so sad to see it changing so much," Bootsma says. "This
isn't the lake it was 25 years ago, and it's probably not the same lake
it's going to be in 10 years."
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