By Tom Meersman
Published June 13, 2004
The Great Lakes have become a giant outdoor biology experiment
-- with no one in charge.
In the space of a few decades, an evolutionary snap of
the fingers, vast populations of foreign fish, mussels
and other creatures have invaded and damaged irreversibly
an ecological design that took thousands of years to evolve.
These unwanted guests in the largest freshwater system
on the face of Earth have muscled out native species,
killed thousands of loons and other migrating birds, devoured
food resources, clogged water-intake pipes and begun to
spill into many of North America's premier interior lakes
Many scientists say the invaders are a worse problem
than the industrial contamination that fouled the Great
Lakes in the 1960s.
They can't be mopped up like a spill or turned off like
a faucet. Some scientists think of the invaders as biological
pollution: They adapt, reproduce and spread. No one species
of invader has been eradicated. Many have no native predators
to keep them in check.
Unlike industrial pollution, much of the new damage
is nearly invisible, hidden in the lakes' murky depths.
Yet biologists who study lakes say the evidence is mounting
that the unintended introductions of species from around
the world could soon dominate the lakes' ecology.
The onslaught also affects Chesapeake Bay, San Francisco
Bay and other North American marine systems, but the Great
Lakes are special because of their immense stores of fresh
water. Some changes could pose a threat to humans, and
health experts have issued warnings about the risks. Botulism
and bacteria that cause cholera are documented consequences
of the invasion. So far, no humans have been reported
At stake is a resource that millions of Americans and
Canadians rely on for drinking water, recreation and their
Many experts say the governments of the United States
and Canada have not done enough to stop potential new
One paradox is that the lakes' improved water quality
of the past three decades, especially in harbors, may
help the foreign creatures flourish.
The invasion of alien plants and animals -- 179 of them
by the latest count -- began in the early 1800s, and it
picked up steam after the St. Lawrence Seaway opened the
lakes to oceangoing ships in 1959. More than 40 percent
of the Great Lakes' invaders have been discovered since
then and most arrived by ship from Europe or Asia, according
to research data analyzed by the Star Tribune.
A new invader is identified in the lakes about every
"They're coming in faster than we can study them,"
said Assistant Prof. Anthony Ricciardi, invasive species
biologist at McGill University in Montreal.
Another scientist who has studied the Great Lakes basin
for 50 years now describes it as "a sick system."
Henry Regier, a professor emeritus of zoology and environmental
studies at the University of Toronto, said he has never
seen such dramatic changes in the lakes.
The alien species have created an "accidental zoo,"
said Prof. James Carlton, director of the Maritime Studies
Program of Williams College in Mystic, Conn. The lakes,
he said, have been permanently modified "on one of
the greatest scales in any aquatic environment in the
To be sure, nature changes on its own over time. Aquatic
populations fluctuate, and some creatures migrate to new
areas or go extinct. And not every introduced fish, worm
or plant disrupts the environment.
Some people question the severity of the problem, but
even the shipping industry concedes that it has transplanted
unwanted creatures around the globe.
North American species also have hitched rides aboard
foreign-bound vessels. An East Coast jellyfish, for example,
invaded the Black and Caspian seas in the 1980s and severely
damaged the anchovy industry and other fisheries.
The unnatural mixing of species from around the globe
has made it an important time to be a biologist studying
the Great Lakes. Researchers are making surprising discoveries
about the invaders and publishing them in scientific journals.
It also is a deeply frustrating and depressing time
for scientists. None can predict how this grand accidental
experiment will play out. And it's possible that the next
generation of researchers will look back on 2004 and remember
the Great Lakes as a system whose ecological collapse
wasn't averted in time.
Scientists rarely make guarantees, but their observations
about the current state of the lakes are consistent in
dozens of studies: The doors for invaders to enter North
American waterways are wide open, and the Great Lakes
are fighting for their lives.
Nowhere has the destruction been more apparent than on
the shores of Lake Erie. Each fall, the skies above the
lake are filled with the flapping wings of loons migrating
south along ancient routes from northern Canada.
In flashes of black-and-white feathers, the loons swoop
down to Lake Erie to rest and dive for fish. Frequently
they snatch the round goby, a 4-to-6 inch European fish
with bulging eyes that has found a new home in the Great
Often the meal is a death sentence.
Scientists say the gobies become toxic food by ingesting
quagga mussels, another recent invader from Europe, which
accumulate botulinus toxin from the lake bottom.
After a loon feeds on a tainted goby, poison attacks
the bird's nervous system, researchers say. The loon's
legs stop working. Soon, it can't flap its wings, hold
up its neck, or keep its eyes open. Within hours, helplessly
paralyzed, the loon drowns and either sinks or washes
up on shore. More than 50,000 loons and other birds died
after eating gobies and quagga mussels over the past five
years -- victims of poisoning.
So many dead birds have washed ashore during recent fall
migrations that beach patrols hauled them away with ATVs
and flatbed trucks. Jason Telecky, a wildlife technician
with the New York State Department of Environmental Conservation,
walked the beaches for two years removing the carnage
so that the botulism in dead birds and fish wouldn't spread
to pets and scavengers. Telecky said his friends jokingly
called him "Dr. Death," but it wasn't funny
after a while.
One afternoon in November at Lake Erie State Park, Telecky
came across a loon with its wings splayed and its body
half-buried in sand. He pulled on a pair of latex gloves,
hoisted the heavy, saturated bird by its legs, and dropped
it into a large plastic bag held by an assistant. About
50 feet away was another loon, its body half-eaten. Farther
down the beach was the apparent scavenger: a dead raccoon,
flat on its back, teeth locked in a grisly grimace.
Loons and other native species evolved in the Great Lakes
after the last Ice Age, about 10,000 years ago. What developed
was a rich, layered freshwater ecosystem isolated from
the rest of the world. It contained 150 species of fish
and innumerable other creatures, a complex mix of predators
A critical link in this food chain are the quarter-inch
Diporeia, pale-orange shrimplike organisms that live on
the bottom of lakes. Loaded with fat, they long have been
a high-energy, abundant food source for fish in the Great
Over the past decade Diporeia have vanished from more
than 17,000 square miles of lake bottom -- an area more
than twice the size of New Jersey.
Every lake except Superior has been affected. Scientists
began to document the losses in the early 1990s, in areas
where zebra or quagga mussels had invaded. As the fish
food disappeared, so did native fish, especially the commercially
valuable whitefish, which depend on Diporeia for up to
70 percent of their diet.
The stories of the loons and Diporeia underscore the
difficulty of predicting how invaders can undermine native
species. Scientists thought they had learned much about
zebra and quagga mussels, but the loon-killing botulism
came out of the blue.
As for the tiny shrimplike creatures, "no one in
their wildest dreams thought that Diporeia would be affected,"
said research biologist Bob O'Gorman, who has studied
the Lake Ontario fishery for the U.S. Geological Survey.
The speed and success of a single species' invasion can
Scientists found a few dozen Eurasian ruffe in the Duluth
harbor in 1986. The small, spiny, perch-like fish from
Europe exploded to 2 million by 1991 and to more than
8 million in 1998, before declining slightly, according
to federal estimates. It now is the most abundant fish
species in the harbor.
One reason that some invasive species are surviving and
proliferating is that harbors and estuaries are cleaner
today. Taxpayers and industries invested billions of dollars
to improve sewage treatment, remove phosphorus and reduce
chemicals, allowing the Great Lakes and their native fish
and wildlife to progress toward recovery during the 1970s
Invaders are undercutting those achievements. The changes
affect not only fish, but also the smallest plants, invertebrates,
snails and mollusks. For example, 20 species of native
mussels lived in Lake St. Clair, part of the waterway
between Lake Huron and Lake Erie, in 1986. Two years later,
zebra mussels spread into the lake. By 1997, all of the
native mussels were gone except in a few shallow areas.
Non-native mussels also have fouled beaches, leaving
mounds of sharp shells and decaying, smelly flesh. In
one extreme example, zebra mussels piled up two feet deep
and 15 feet wide along a quarter-mile of beach near Green
Bay, Wis. In lake cities such as South Haven, Mich., anglers
fishing offshore often reel in unwanted non-native fish.
Invaders also pave the way for future intruders.
The newcomers sometimes alter the habitat in ways that
help other alien creatures to thrive.
For example, invasive gobies spread quickly in areas
where zebra mussels have become established because the
gobies eat the mussels. In other places, zebra mussels
attach themselves to non-native Eurasian watermilfoil
plants. The mussels gain a place to live, while the milfoil
grows better because the clinging mussels filter and clear
This positive interaction between foreign species represents
a dangerous shift in the lakes' ecology that has been
called "invasional meltdown." University of
Tennessee biology Prof. Daniel Simberloff, who coined
the term, said damage to native creatures may accelerate
if clusters of invaders remake the aquatic habitats. The
biggest losers could be native species that already are
endangered, he said.
Invaders also pose human health risks. The botulism outbreak
that killed loons and other birds also poisoned hundreds
of thousands of fish. New York officials issued health
advisories warning anglers not to handle or eat sick fish
and game. No human cases of botulism have been reported.
Scientists are concerned that pathogens could enter the
United States by the same pathways that invasive species
use, potentially spreading human diseases. Smithsonian
scientists found bacteria that caused cholera four years
ago in 15 ships' ballast tanks in the Chesapeake Bay,
for example. Again, no human illness was reported.
People with decades of experience fishing on the Great
Lakes have seen both warning signs and actual damage.
For Don Scott, a fishing guide in Ontonagon, Mich., the
changes have meant that customers who fish for northern
pike and walleye spend much of their time hauling in 4-inch
Eurasian ruffe. The fish's populations have skyrocketed
in the Ontonagon River and other waterways. "We get
slammed with them," Scott said.
Sportsmen still catch native fish, but that may not be
true in a few years if the ruffe continue to expand, Scott
Tom Marks, a sport fisherman on Lake Erie for more than
four decades, mainly blames invasive zebra and quagga
mussels for a 75 percent decline in Erie walleye since
the mid-1980s. The mussels feed on nutrients that young
fish need to survive. Marks, who is former president of
the Southtowns Walleye Association of Western New York,
said the result is fewer young walleye, and a shortage
of prey such as perch, minnows and smelt for the larger
How they arrive
Commercial shipping, one of the economic engines of the
Great Lakes, also drives the ecological decline.
Ships have been the main carriers of invasive species
into the Great Lakes. An empty cargo vessel headed for
Duluth may contain 2 million gallons of water in its ballast
tanks to keep it safely balanced. Virtually all of it
will be dumped into the harbor as the vessel takes on
grain or other cargo.
The problem is that ballast tanks also may contain thousands
of organisms hitchhiking rides from foreign ports. Many
oceangoing vessels are inspected under a U.S. Coast Guard
program, but experts say the invaders still can find their
way into North American harbors aboard ships.
Two-thirds of the invaders discovered in the Great Lakes
since 1960 likely came from shipping, mostly from ports
in northern and eastern Europe, researchers say.
Dozens of species from the Black and Caspian seas have
hopscotched across Europe, settling in ports of the Baltic
and North seas. Now, researchers say, species such as
the "killer shrimp," so named because the one-inch
creature devours and destroys vast amounts of fish food,
soon could show up at the Great Lakes' doorstep.
Fish farms in the United States also contribute to the
problem. Two kinds of Asian carp imported to clean U.S.
fish farm ponds and tanks escaped into southern waterways
in the early 1980s. They have spread up the Mississippi
River and its tributaries toward Lake Michigan.
Fearing that the carp may jeopardize a $4.5 billion commercial
and recreational Great Lakes fishery, the U.S. Army Corps
of Engineers and the state of Illinois are building a
$7 million electric barrier south of Chicago to try to
halt the carp. And a different type of barrier on the
Upper Mississippi River is being considered.
The barriers may not be enough. Invasive species also
have entered the lakes through bait buckets, as anglers
intentionally or inadvertently dumped them into the water.
Unwanted aquarium fish have been released into waterways
because their owners thought it was a humane or convenient
way to dispose of them.
About a third of the invasive species in the Great Lakes
basin are aquatic plants, such as Eurasian watermilfoil,
which have been spread by ships, boats, trailers, garden
nurseries and other means. This vegetation can overtake
lakes and interfere with boating, fishing and swimming.
Cost to society
This invasion results in an enormous cost.
Take just one species: Zebra mussels, which look like
thumbnail-sized clams with dark and light stripes, have
cost industries, water companies and power plants nearly
$2 billion, according to Chuck O'Neill, a coastal resources
specialist with New York Sea Grant, an extension program
of Cornell University and the State University of New
York. The mussels, originally from the Caspian Sea, clog
water intake pipes and other equipment and need to be
removed periodically with chemicals or other means.
Other experts have tossed around damage figures in the
billions of dollars for commercial fishing, recreation
and tourism. But the hardship to native species is not
easily rendered into dollars and cents.
Many feel that it's impossible to assign a cost to a
70-year-old endangered sturgeon in Lake Ontario killed
by botulism, for example, or to the disappearance of perch
and walleye from a favorite fishing hole, or to the loss
of a clean swimming beach.
Putting a price on the ecological decline of the Great
Lakes "is just utterly stupid and immoral,"
said Regier, the researcher from Toronto.
The business health of the Great Lakes also is at stake.
Regulations on shipping, fish farming and the pet industry,
for example, could affect trade. "We should not go
back to pre-Columbian times," said Marshall Meyers,
executive vice president of the Pet Industry Joint Advisory
Council, a trade association that includes importers of
animals sold as pets. "We are in a global economy."
Meyers said the ecological problems caused by the creature
invasion are too often exaggerated.
However, taxpayers already are paying a price because
it is costly to keep invaders' populations in check. The
sea lamprey, an eel-like parasite that attaches itself
to fish, came from the Atlantic Ocean through canals.
U.S. and Canadian governments spend $16 million annually
to trap, sterilize and poison millions of lampreys. The
program will never eradicate them.
The lamprey, because it spawns in streams, is vulnerable
to human control efforts. For most established aquatic
invaders, scientists can do nothing to interrupt their
While experts have been raising red flags about the invaders
for decades, they have received little public or government
attention. Almost all federal funds provided to counter
foreign species are devoted to terrestrial pests that
threaten agricultural crops and forests, not to aquatic
"We're completely in a reactive mode in dealing
with these invasive species, in both the United States
and Canada," said Prof. Hugh MacIsaac, invasion biology
research chair at the University of Windsor and one of
Canada's leading researchers on the issue.
The invaders have spread within the Great Lakes and beyond.
Zebra mussels, alien plants, fish eggs and larvae can
be picked up in boats, trailers and bait buckets and whisked
inadvertently to any fisherman's or boater's favorite
That has hit home for Bob Franseen, who learned in October
that Ossawinnamakee Lake in north-central Minnesota had
become infested with zebra mussels. The lake, where he
lives year-round, is 110 miles from the nearest known
zebra mussel infestation in Minnesota. A worker found
the mussels on several docks that he removed last fall.
"The news came like a grenade tossed into the middle
of things," Franseen said. At the time, lakeshore
owners were busy trying to stop the spread of Eurasian
Residents and state officials are concerned that the
popular recreational lake will become the bull's-eye from
which boaters and anglers inadvertently carry the mussels
to neighboring lakes. Mussels, especially tiny young ones,
are frequently transported in water that accumulates in
boat engines, bilges and live wells, or on aquatic weeds
that become entangled in anchors and boat trailers.
Natural resource authorities have redoubled their efforts
to warn people about cleaning boats and trailers and emptying
bait buckets on shore to reduce those risks.
Ossawinnamakee is the second lake in Minnesota where
zebra mussels have been found, after Zumbro Lake in the
southeastern part of the state. Michigan has 185 infested
lakes, Wisconsin has 44, and Ontario has dozens, especially
along a highway of interconnected lakes, rivers and canals
that extends more than 200 miles between lakes Ontario
The spread of invasive species in Ontario threatens a
$1.4 billion-a-year recreational fishing industry. "We
have been warning for years that invasive species in the
Great Lakes like zebra mussels and round gobies were going
to get into the inland waterways," said Greg Farrant,
government relations manager for the Ontario Federation
of Anglers & Hunters. "Well, now it's happened.
The invasion is far from over -- and stopping more destructive
creatures like the killer shrimp from entering the Great
Lakes won't be easy.
On ships, the ballast water and residue in the tanks
would need to be filtered or exposed to heat, chemicals,
ultraviolet light, ozone or other treatment to kill unwanted
creatures. Ship owners are unwilling to make such changes
on their own because they say that the technologies are
experimental, and that government officials have not established
limits for how many organisms need to be killed or removed.
In February, after years of discussion, the International
Maritime Organization, a U.N. agency, adopted a convention
on ballast water. It offers no immediate remedy. Ballast
treatment standards would take effect for new ships in
2009 and for existing vessels beginning in 2014, if enough
nations ratify the treaty.
Those regulations may be too late for the Great Lakes.
Researchers have been calling for immediate action for
the past 15 years. In the latest attempt to push for changes,
750 scientists, resource managers and other experts sent
a letter in December to Congress and President Bush. They
asked for new laws and more money to protect the Great
Lakes and other areas, because "the devastation caused
by non-native, invasive organisms is one of the most serious
and least-recognized tragedies of our time."
For two years Congress has been studying whether to strengthen
laws about invasive species. Two House subcommittees held
a joint hearing in March, but it is unclear whether legislation
will be passed.
U.S. officials also have considered establishing a national
screening system to prohibit imports of creatures with
a high potential to spread uncontrollably in the wild.
Such a system already exists to exclude foreign plants
that could endanger agricultural crops, but the worldwide
trade in fish, aquatic plants and other potential invaders
remains largely unregulated.
Fish such as Asian carp also can invade waterways through
the live food market if unsold fish are dumped live into
ditches, canals or lakes. Chicago, New York, and the province
of Ontario recently began requiring that live bighead
carp be killed at the point of sale or before disposal.
In the meantime, invaders continue to be discovered,
and no one knows how much havoc the next one may wreak.
"Every time we have a new species that enters the
Great Lakes, we're instigating yet another unplanned and
uncontrolled biological experiment on our ecosystem,"
said David Reid, a research scientist at National Oceanic
and Atmospheric Administration's Great Lakes Environmental
Research Laboratory in Ann Arbor, Mich. "We are playing
ecological roulette with the Great Lakes."