Lake Erie's Health Crisis
Lake Erie once again is showing signs of an environmental
crisis, after nearly two decades of mostly good news about
the health of the lake.
say a number of factors are again straining the most vulnerable
of the Great Lakes: a fourth straight year of large-scale
fish and bird die-offs, a large "dead zone" off the Ohio
shoreline and the threat of invasion by another non-native
species with a voracious appetite.
"Lake Erie is
like the canary in the coal mine," said Margaret Wooster,
executive director of Great Lakes United.
"It's the most
shallow and the most vulnerable," she said. "It's the
one where we're already beginning to see the signs we
saw in the 1960s, only now we're looking at a more diverse
and complex set of causes."
was at the root of the lake's woes 40 years ago, lake
watchers theorize that the current problems may be the
proliferation of invader species like the zebra mussel,
quagga mussel and the round goby.
is that these species are consuming large quantities of
the microscopic life forms that constitute the base of
energy in the lakes, creating another link in the food
chain that is having far-reaching impact.
- and this is still a theory - that the exotic species
mixture is the real root of the problem," said Bill Culligan,
who heads the state Department of Environmental Conservation's
Lake Erie Fisheries unit in Dunkirk. "The gobies and the
zebra mussels and the things that eat those two things
are the ones being affected."
The round goby
and the zebra mussel have changed the lake, but lake watchers
are bracing for another intruder they fear could be an
even larger invader: the Asian carp.
China in 1973 to improve the water quality in aquaculture
operations in Arkansas, the carp managed to escape those
confines and multiply rapidly in the surrounding states'
rivers and lakes.
They have advanced
into the Illinois River as far as Joliet, Ill., only 25
miles from Chicago. If they get that far, they will be
at the Great Lakes' door and, as Jerry Rasmussen of the
U.S. Fish and Wildlife Service said, "I don't think you
The larger types
of Asian carp, the bighead and the silver, have an appetite
that would put Homer Simpson to shame. They can weigh
up to 100 pounds and grow to more than four feet long.
"Some say they'll
consume up to 40 percent of their body weight in a day,"
said Rasmussen, who has studied the carp as it has traveled
north up the Mississippi River. "Silver carp has been
described as not having a stomach: food in and food out,
a constantly consuming machine."
Some of the fish
grow to 12 pounds in their first year of life, and often
become so large that they are no longer a threat to native
carp extremely prolific
are also extremely prolific: A female can carry up to
1 million eggs. The carp quickly supplant native fish.
In fact, fishermen have abandoned some of the more fertile
commercial fishing zones along the Mississippi because
of Asian carp infestation.
"They feed on
plankton, so they take the algae that are the basic productivity
of the floating population, the things small fish feed
on," Rasmussen said. "You can imagine that if you get
large (carp) in large schools, they'll tie up a lot of
biomass. And right now, that's what we're seeing in our
installed an electrical barrier in the Chicago Sanitary
and Ship Canal that they hope will slow the northward
movement of the carp. It works by creating impulses that
repel the fish.
What would happen
if they get in the lakes is anybody's guess, but Rasmussen
believes Lake Erie is the most vulnerable.
"It's the shallowest,"
he said. "It's more (like) the habitat they're familiar
already have enough to occupy them, including the reappearance
of a large "dead zone" unable to support life in Lake
Erie's central basin.
Much of Lake
Erie was anoxic, or oxygen-deprived, in the late 1960s,
but after millions of dollars was spent on upgraded sewage
treatment plants, that condition had been turned around.
Now it appears
that an area on the lake between Ohio and Ontario once
again contains pockets where oxygen has been stripped
from the water. It's enough of a concern to prompt a $2
million research project involving U.S. and Canadian scientists
who will take instrumentation out onto the lake throughout
There are three
possible explanations, according to Jan Ciborowski of
the University of Windsor, one of the scientists in charge
of the program.
One is that warmer
water temperatures are reducing the size of the oxygen
pool in the middle of the lake.
Another is that
algae that normally produce oxygen are, for some reason,
unable to do so now.
A third explanation
is that decaying fecal matter, animals and algae are draining
oxygen from the water.
"Each of these
is a possible explanation, and the reason we're looking
together is to see which of these hypotheses is supported
by the data," Ciborowski said."
Signs of a disrupted
ecosystem became apparent on the lake in 1999, when scientists
dissecting dead wildlife found along the lake shores discovered
the animals were killed by type E botulism. Last found
in some of the other Great Lakes in the 1960s, it had
never been found before in Lake Erie.
The number of
dead birds and fish mushroomed in 2000. Early in the summer,
it was a large die-off of mud puppies, an aquatic salamander,
on the Canadian shore, but as the year went on, larger
creatures began floating up on the shoreline between Buffalo
and Erie, Pa.
it's safe to say that "tens of thousands" of fish, mostly
sheepshead, rock bass and smallmouth bass, have been killed
in each of the last two summers.
deaths from botulism
to estimates based on samples of sections of the shoreline,
the state believes around 6,000 water birds died along
New York's Lake Erie shore in 2000. There were another
2,600 estimated deaths last year, almost half of which
were common loons, but DEC senior wildlife pathologist
Dr. Ward Stone thinks that estimate is low.
Some of the fish
deaths can be attributed to natural causes or natural
conditions, like thermal shock, which occurs when temperatures
change too quickly for the fish to adjust. But Stone said
many died from botulism.
This year, there
has been another large mud puppy die-off, this time on
the New York shore, as well as a large number of dead
"A few days ago,
there were at least 2,000 (gulls) dead," said Stone, noting
that this year's bird die-off has come earlier than the
previous two years. "They got the Type E botulism somewhere."
may be due to invaders
has not been identified yet this summer in fish, but Stone
believes testing on fish brought in late last week will
confirm its presence.
the appearance of botulism is related to the invaders,
the round goby and the quagga and zebra mussels.
The mussels filter
microscopic food call phytoplankton from the water. That
makes the water clearer, allowing sunlight to promote
algae growth at deeper than usual levels. The algae eventually
dies and combines with decomposing mussel waste to provide
a fertile breeding ground for the bacterium that leads
which absorb the bacterium, are eaten by gobies and other
fish, which then are weakened by the disease. The debilitated
fish attract larger predatory fish, mud puppies and diving
fish-eating birds like loons who, in turn, become sick.
"What I think
is that the botulism started out in fish or mud puppies,
and now it is going through by birds eating fly larvae"
coming out of the decomposing fish and birds along the
shoreline, Stone said.
they're still trying to prove some of their theories on
how invasive species are changing the lake ecology. Lake
advocates like Gordon Fraser, director of the Great Lakes
Center at Buffalo State, say additional research is essential.
"We don't have
a lot of hard data," he said. "And we're not getting a
lot of support to go out and get it."
has dead zone
By John Bartlett
Two research vessels, one Canadian and one American, crisscrossed
Lake Erie's central basin Friday looking for a "dead zone,"
an area of water deprived of oxygen.
The work is taking place with urgency, and with concern
for how an oxygen-poor lake would affect marine life and
the communities that rely on the lake's water quality.
Lake Erie's central basin is showing signs of excessive
oxygen depletion, a problem officials believed they had
solved decades ago with the cleanup of the lake and tough
new pollution standards in the 1970s.
Fish and other aquatic creatures need oxygen. When too
little oxygen is in the water, fish and other aquatic
species cannot survive, and a "dead zone" forms.
Most species are OK until the dissolved oxygen levels
fall below 6 parts per million, or ppm. Below that, they
are stressed, much as a person would be breathing at a
high altitude. At below 4 ppm, most aquatic species will
be literally choking for air.
"A lake trout might prefer it above 6 (ppm) or close to
10 (ppm), which is about as saturated as you can get,"
said Roger Kenyon, a Lake Erie fisheries biologist with
the Pennsylvania Fish and Boat Commission. "A carp may
not be affected until it falls to 2 (ppm). Much below
2, it's fairly toxic for everything."
By the end of August, oxygen levels fell below 2 parts
per million throughout the central basin, creating what
biologists are calling a massive dead zone.
"Last year was one of the most rapid and largest oxygen
depletions we've seen since 1983," said David Rockwell
a senior scientist with the federal Environmental Protection
Agency's Great Lakes National Program office.
It does not bode well for the lake, nor for the communities
and people who are so heavily dependent on its water quality,
said Gerald Matisoff, a Case Western Reserve University
professor who is co-coordinating the current U.S.-Canadian
Every summer, oxygen levels decline in the central basin
when the water in the Great Lakes separates into two layers
in which the warmer, top layer traps the colder waters
beneath it. The top layer mixes with oxygen from the air,
while the bottom layer is cut off from the air supply.
Whatever oxygen the bottom layer has when the separation
occurs is all that is available until the end of the season
and the annual remixing of the waters.
Lake Erie's western basin is shallow enough for the winds
to stir the entire water column, providing the opportunity
to dissolve oxygen throughout its depths. The eastern
basin is so deep, its volume alone largely ensures an
adequate oxygen supply.
The central basin, however, falls somewhere in the middle
and the annual oxygen loss can become severe if something
goes wrong, Kenyon said.
Apparently, something has gone wrong, but what it could
be remains a puzzle.
In the dark days of Lake Erie's past, the problem played
out fairly directly.
Phosphorus and other nutrients were dumped into the lake
from sewage plants and other sources. The nutrients fertilized
algae, which led to massive algae blooms, which eventually
would die and decay. As the algae decayed, it used up
the oxygen in the lake, creating anoxic, or oxygen-poor,
The cycle nearly overwhelmed Lake Erie by the end of the
1960s, leading to its portrayal as a dead lake.
U.S. and Canadian communities and governments spent billions
of dollars on new and updated sewage systems, and the
use of phosphorous in detergents and other products was
Lake Erie quickly rebounded in one of the great environmental
success stories of all time.
What particularly puzzles scientists now is that the conditions
in the central basin do not seem to correspond with large
"Based on studies in the '60s and '70s, we cut the amount
of phosphorous we put in the lake to 11,000 tons a year.
It had been running as much as 25,000 tons a year before,"
Case Western Reserve's Matisoff said. "We met that goal
in about a decade and saw steadily improving water quality,
and now we see the problems we had in the '70s and earlier.
We don't understand that."
Looking back, researchers now realize the seasonal oxygen
declines in the central basin started to become a problem
in 1995. The realization that anything unusual was going
on came as Great Lakes researchers compared notes at a
conference in 1999, said Jan Ciborowski, Matisoff's Canadian
"The change was almost imperceptible at first in 1995
through 1999, then it became quite rapid in the last couple
of years," he said.
Several theories have been suggested for the increased
levels of phosphorus and the ensuing oxygen-deprived conditions.
Basically the theories fall into three general categories
— climate change, unaccounted for sources of phosphorous
and the effects of zebra mussels and their cousins, the
Matisoff said the invasive mussels are highest on his
suspect list, and the focus of most of the current research.
"The idea is the lake functioned one way before the zebra
mussel, and that the zebra mussel has changed how it functions,"
Zebra mussels have created clearer lake waters, allowing
sunlight to penetrate deeper, which possibly has led to
algae growths at deeper levels where there is less oxygen
and where the impact of decay, pulling oxygen from the
water, would be greater.
Mussel feces contains phosphorous, and the sheer volume
of mussels and their waste might be what is throwing things
out of balance.
"What we are seeing could be the result of a whole bunch
of factors happening at once," Ciborowski said. "We don't
know, and that's scary. We spent a huge amount of resources
to correct the problems we had in the past. We developed
a model that seemed to be working nicely until now. Are
we deluding ourselves that we can manage the lake?"