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Great Lakes Article:

Dead in the water

We spent billions to clean up the Great Lakes and show the world that even severe environmental injuries can heal. But the celebrating began much too soon. In this special report, MARTIN MITTELSTAEDT reveals that not only is Lake Erie dying again, scientists fear that this time there is nothing they can do to save it


MARTIN MITTELSTAEDT
The Globe and Mail
Posted 10/08/2002

WHEATLEY HARBOUR, ONT. -- On June 22, 1969, the Cuyahoga River did something rivers are not supposed to do. It caught fire. Flames burst out along several kilometres of the oil-coated waterway where it flows through Cleveland's gritty industrial heartland toward Lake Erie. Embarrassed municipal authorities dispatched three fire battalions plus a pumper boat, the Anthony J. Celebrezze, to knock out the blaze, which raged five storeys high and damaged two key rail bridges.

The Cuyahoga had burned before but this time the news that pollution could make a river flammable caught the public's imagination. The incident became a global symbol of environmental degradation, and scientists started to look closely at what dozens of dirty rivers were doing to Lake Erie, the most southerly of Champlain's five "sweetwater seas."

To the amazement of people in Canada and the United States, they discovered that Erie was dying. Stinking masses of algae and rotting seaweed had turned its once-azure water a murky green; every summer, so much of the lake was being depleted of oxygen that a terrifying dead zone was forming on the bottom.

Spurred to action, government and industry spent billions on pollution controls, upgrading sewage-treatment plants at big U.S. cities such as Detroit and Cleveland, and sparked an environmental renaissance. By the mid-1990s, the lake was being held up as proof that environmental degradation can be overcome. It was deemed to be cleaner than it had been in 50 years, and many of those responsible for its recovery moved on.

But there was a problem with Lake Erie's return from the brink. It didn't last.

Lake Erie is in serious trouble. The dead zone is growing again, and the floating mats of smelly algae are back, along with a blue-green variety that is toxic. As in the 1960s, a vicious strain of avian botulism is claiming thousands of the birds that feed on Erie's fish, and chemical toxins are building up in the fish and fowl.

The walleye -- the top fish in the lake's food chain -- is also in trouble. Prized for its tasty white flesh, the species has undergone a dramatic population crash in Lake Erie, from about 100 million in 1988 to less than one-third of that two years ago. And while the cleaned-up Cuyahoga no longer catches fire, fish in parts of the river suffer from persistent and mysterious tumours.

Nobody really knows what is causing all this, except that "we declared victory too soon," admits David Dolan, a professor of applied science at the University of Wisconsin at Green Bay who tracks phosphorus pollution for the U.S. Environmental Protection Agency. "We let our guard down. It wasn't over."

So a huge EPA-financed team of Canadian and U.S. researchers has attacked a body of water almost five times the size of Prince Edward Island this year in search of clues. The theories range from global warming to the possibility that zebra mussels and other alien species from the Black Sea have so altered the ecology that all the old scientific rules no longer apply.

The situation is critical because Erie acts as a kind of sentinel for the rest of the Great Lakes, the world's largest body of fresh water. Bad things usually show up first on the shallowest and warmest of the big lakes because Erie has far more aquatic life and far less water than the others.

In fact, the renewed algae blooms plaguing Erie have already begun to crop up elsewhere -- on "Lake Huron, Lake Ontario and I've heard reports from Lake Michigan," says Ralph Smith, a biologist at the University of Waterloo.

He warns that "we can definitely point to quite a few trends that are reversing, things moving back in the wrong direction, the algae, the fouling of the beaches. It's not just a one-summer peculiarity. It's happening too regularly."

Mr. Smith says his research vessel often stalls, sometimes 10 kilometres from shore, when clumps of algae clog its propellers, and he predicts that people who like to think of Erie as relatively clean are in for a shock. "The amenity value of the lake is at peril right now. I'd hate to be a shoreline property owner. I'd be worried."

Of all the problems, the dead zone alarms researchers most. It is a wide portion of the lake's central basin between Cleveland and Port Stanley on the Ontario shore where in summer the deeper water suffers from anoxia -- it's almost devoid of oxygen and thus lethal to aquatic life. Any fish that swims to the depths and lingers too long suffocates.

Researchers thought this problem had been solved by the controls on phosphorus imposed in the 1970s, but water samples taken from the basin last year showed that its oxygen content had declined more rapidly than anything seen in almost 10 years.

Some scientists believe that the central basin may have always had a small dead zone simply because of the way water in large lakes tends to form layers based on heat. Winter turbulence means than in spring Erie's water is pretty much a uniform temperature, with oxygen content identical from top to bottom. But once the surface begins to warm in the summer, the lake's water column divides into two.

Being less dense, warm water rises to the top and sits on the heavier, colder water. The two become as distinct as layers in a cake, with the surface water always exposed to air, but because it doesn't mix with what's below, oxygen at the bottom isn't replenished. Whatever is there when the lake stratifies in spring has to last until early fall when surface cooling restores the lake's uniform temperature. Only then do the layers merge, permitting wind and wave action to drive fresh oxygen to the bottom.

The part of the basin that runs out of oxygen is "always here," says Tim Johnson, who is in charge of Erie research for the Ontario Ministry of Natural Resources, "but suddenly it seems to be growing worse. That was the part that puzzled us."

Surface water in spring can have as much as 12 parts of oxygen per million while readings in the dead zone have plunged to 1 ppm -- one-quarter of the amount that leaves big fish such as salmon and lake trout highly stressed. Anything less and they may as well be on life support.

Phosphorus is the key nutrient that controls the lake's ecosystem -- in excessive amounts, it's like a steroid to algae, driving growth out of control. When algae dies, it sinks to the bottom and rots, depleting the water of oxygen.

In the early 1970s, scientists believed that slashing the phosphorus pollution would make the dead zone disappear. Canadian and U.S. governments set their sights on allowing only 11,000 tonnes into the lake every year, versus almost nearly 30,000 tonnes in the sixties. They reached their target in the early eighties, thanks to bans on phosphates in detergent and improved sewage treatment.

Since then, the annual figure has varied, but has generally stayed under the limit, at least according to official records -- about 9,000 tonnes in 2000 and only 7,000 tonnes a year earlier. And still the dead zone continues to grow, which leaves scientists scratching their heads.

"We kind of hoped this oxygen depletion would be a lot, lot better by now," concedes Murray Charlton, a researcher at Environment Canada.

Mr. Johnson of the MNR is equally perplexed. The arrival of the zebra mussel in the 1980s altered the way phosphorus is distributed in the lake, he says, but concentrations of the pesky mollusk have stayed much the same in recent years. "Phosphorus loadings haven't changed, mussel densities haven't changed diametrically, and so why now," he wonders, "is the lake suddenly changing, reverting back to more of a 1970s state?"

Suspicion has fallen upon the official figures -- should they be so rosy? Perhaps not. They are based on estimates and voluntary reporting by polluters, and even Mr. Dolan, who tracks the data for the EPA, questions their reliability.

The task is further complicated by the fact that, when Lake Erie looked so healthy 10 years ago, scientists dismantled much of its pollution monitoring. Thinking Erie had been saved and facing major government budget cuts, they assumed money could safely go to more pressing problems. Now, only eight instead of all 30 major rivers running in the lake are monitored, even though they carry most of the fertilizer runoff from farms, the single biggest source of phosphorus. Farmers face no restrictions on its use even though it is so soluable in water that anything not immediately absorbed by plants is washed from a field by the next rain.

Spending cuts also have reduced the number of spot checks conducted to verify the emission claims of sewage-treatment plants, which Mr. Dolan says are running out of capacity because of population growth and suburban sprawl. To make matters worse, major U.S. cities such as Detroit have antiquated systems that carry human waste and storm water in the same pipes. This approach doesn't cause extra pollution -- as long as it never rains.

"The sewage treatment plants are at their capacity and it doesn't take much of a rain, a half-inch or a quarter-inch, and they're already overflowing," Mr. Dolan says. "What you'd like to see is them handle at least a moderate rain before overflow starts."

He tries to account for how much untreated phosphorus this generates, but the calculation is imprecise. "I'm concerned that if trends continue, I won't be able to make a credible estimate at all. I know I'm under-reporting," he says but he is "probably missing 10 per cent at worst."

Dealing with the phosphorus problem this time promises to be difficult. Back in the 1970s, the cleanup meant upgrading a few dozen highly visible sewage-treatment plants and industrial polluters. Any reductions now will require weaning tens of thousands of farmers in the lake's watershed off the synthetic fertilizers they've come to rely on.

According to Mr. Dolan, voluntary appeals have been tried and just don't work. There has to be a strict limit on fertilizer use or producers have to make a mass switch to sustainable farming. "Until they actually regulate it, I don't think you're going to see appreciable changes. People are concerned about the yield of their crops, and phosphorus is the short track to increasing their yields."

Global warming also may play a role in the burgeoning dead zone.

Municipal intake pipes that draw supplies from the lake have shown a consistent increase in temperatures since the early 1960s. This added warmth may be extending the period that Erie is stratified every year, forcing the deep zone to subsist even longer on its springtime oxygen infusion.

Warming also dries up the lake, lowering water levels in each of the past three years. The central basin is typically about 22 metres deep, with the dead zone occupying the bottom two or three metres. A thinner water column could lead to a thinner cold-water zone at the bottom and a smaller reservoir of oxygen.

Scientists realize there is nothing they can do about global warming, but they aren't convinced that either climate change or phosphorus is the only culprit. Some believe that much of the blame belongs to two tiny foreign invaders: the thumbnail-sized zebra mussel and its relative, the quagga mussel.

When they arrived, most likely in bilge water dumped by an ocean-going tanker, they were viewed as just a nuisance that clogged water pipes and cut swimmers' feet. But they had one beneficial effect, at least from the human perspective. By filtering out the microscopic algae they like to dine on, they made Erie's water much clearer.

But now some scientists speculate that the mussels are far more pernicious, causing not only the dead zone, but the renewed growth of toxic algae, avian botulism and toxic chemical contamination of wildlife.

They grow in dense mats -- thousands per square metre -- on the lake bottom not far off shore. Mr. Smith, the Waterloo biologist, is trying to determine whether they have become so numerous that, between the food they draw to the bottom and the waste they generate, their presence is what's robbing the water of oxygen. "The possibility is that they are moving a lot of organic particles into the deep zone of the lake," he says. "An obvious candidate would be the fecal material of the mussels themselves."

By depleting the oxygen, the mussels also may be creating an ideal habitat for botulism, which is caused by Clostridium botulinum,a nasty bacterium that thrives in oxygen-starved waters. Environment Canada biologist Jeff Robinson warns that "this is a working theory -- at this point, we haven't proven it," but the bacterium is a natural part of Lake Erie's ecosystem and usually hasn't been much of a problem. "Traditionally . . . conditions would very rarely come together to allow this botulism toxin to move up through the food chain," he explains.

So, something has happened to allow it to kill off thousands of waterfowl along the Lake Erie coastline since 1999, including, scientists suspect, a major attack this year near Long Point, Ont. As well, the disease has attacked birds on Lake Ontario and on the Canadian side of Lake Huron, wiping out loons around Grand Bend.

How does a disease created on the bottom reach birds on the surface? Researchers have begun to suspect that another newcomer -- the round gobi -- plays a major role. A bottom dweller first seen in Erie in 1993, it is now among the lake's more abundant fish. It preys upon its fellow Black Sea natives, the mussels, and in turn is a favourite food of mergansers and other waterfowl, which may be how they contract the botulism.

The end result, says Mr. Robinson, who is recording the death toll for the Canadian Wildlife Service, isn't for the faint of heart. "It's pretty disturbing to see large numbers of [dead] fish and sick and dying birds."

Margrit Kapler agrees. She has a cottage at Point Ryerse, just west of Port Dover, Ont., and has been a happy neighbour of Erie for 30 years. But on the Labour Day weekend, she was shocked to see hundreds of dead fish and birds start to wash up on her beach. Worried by the smell, she began to bury the carcasses but found she couldn't keep up. It turned into a long weekend of death on the beach. "I have never seen anything like that," she says.

As well as botulism, the zebra mussel is linked to renewed outbreaks of cyanobacteria, the toxic blue-green algae that produced huge "blooms" at the western end of the lake until the 1970s phosphorus-abatement program. Suddenly, in 1998, it made a major comeback and this summer, after laying low for three years, came back yet again.

The blooms can kill people, although the Great Lakes region has no known victims, and their return may be due to excessive farm fertilizer. Or it may be because zebra mussels feed on the algae but spit out the cyanobacteria, in the process helping them thrive while eliminating many competitors.

Higher on the food chain, the picture looks no brighter.

In August, fisheries researchers from Ontario, Ohio and Michigan conducted their annual trawl of the lake in search of young walleye that were born this spring. "We didn't find any," says John Cooper of the Ontario Ministry of Natural Resources. "We've never seen it this bad before."

The walleye may have had a difficult spawn because the spring was so cool. But the fish also prefers murky water -- its eyes have adapted to feed in low-light conditions -- and the zebra mussel is making Lake Erie too clear for them.

Jolted by the decline, Ontario and state governments bordering the lake have have cut fishing limits in half to see if stocks can be rebuilt.

The walleye is important because it is what's called a keystone species. Just as a keystone supports all the bricks in an archway, an ecosystem's keystone creature stabilizes the entire community. If the walleye is in trouble, fish it preys upon -- smelts, for example -- may run riot, taking over the lake, as they did in the 1960s.

With Lake Erie in such dire straits, what can be done to help it?

In the 1960s, when scientists discovered that phosphorus was such a problem, there was a sense of confidence. The solution was simple: Reduce the amount of chemical reaching it, and Erie would recover.

Now, the researchers are far less certain. They consider the challenges the lake faces to be far more daunting -- perhaps even unfixable.

Roger Knight, supervisor of Ohio's Sandusky Fisheries Station, has studied Erie for 20 years and still considers it "a much better lake than it was in the sixties and early seventies."

But he worries about the impact of the alien species and feels these exotic "bad guys" are causing an "unprecedented level of change" and "now dominate a large part of the community."

He says biological pollution is more difficult to counteract than other environmental threats. If chemicals are a problem, levels can be reduced or a product banned altogether. Not so with a round goby or zebra mussel, whose prodigious breeding overwhelm any control efforts. "There is nothing you can do to eliminate these unwanted guests," Mr. Knight says.

Hugh MacIsaac, a biologist with the University of Windsor's Great Lakes Institute, also worries that the foreign species, coupled with climate change and all the toxic chemicals, may pose a threat far greater than that of the 1960s. "We have problems that are at least as pressing, and even maybe more pressing than some of the ones that we thought we had solved," he explains.

The MNR's Mr. Johnson warns that Erie, although cleaner than before, is in an "extreme state of turbulence." Based at the ministry's Lake Erie fisheries station, a collection of metal-clad buildings at Wheatley Harbour, he works within a few feet of the trouble lake and says that all he knows about the answers to its problems is that they won't be easy.

"The more time I spend here," he says, "the more I realize the true depth and breadth and complexity of the issues."

Martin Mittelstaedt writes on the environment for The Globe and Mail.

Erie by the numbers

Length: 388 kilometres
Width: 92 kilometres
Average depth: 19 metres
Maximum depth: 64 metres
Volume: 483 cubic kilometres -- *fifth among Great Lakes
Shoreline: 1,402 kilometres (including islands)
Surface area: 25,655 square kilometres -- *fourth among Great Lakes
Age: 14,000 years since last glacier, 4,000 years in present form
Neighbouring population: 10.5 million U.S. and 1.9 million Canada

* Lake Ontario has a smaller surface area, but holds more than three times as much water.


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