Over the past year, Michael Rennie has dumped 30,000 tiny freshwater shrimp into a remote lake in northern Ontario.

Rennie, a freshwater ecologist at Lakehead University in Thunder Bay, is trying to find out if these shrimp can help the lake’s ecosystem recover from an environmental catastrophe that many people probably thought had already been solved: acid rain.

Anyone who was alive during the 1970s and ’80s in North America will remember acid rain as the big environmental issue of the time. Dead lakes, corroded statues and spiking rates of asthma made for compelling stories on the evening news. But as measures to deal with the pollution came into effect, the issue slipped from public consciousness, even though the story was far from over.

“Many people probably feel that we’ve solved acid rain, because there is a lack of awareness that the recovery will take a long time,” says Karen Kidd, an ecotoxicologist at McMaster University.

Scientists are experimenting with adding mysis shrimp back to a lake in northern Ontario, which has been used in experiments about the effects of acid rain. Photo: IISD Experimental Lakes Area

What exactly is acid rain? 

Acid rain forms when nitrogen oxide and sulphur dioxide gases are released into the atmosphere from the burning of fossil fuels. Those gases react with water molecules in the atmosphere to produce nitric and sulphuric acids, which then fall across the landscape as rain, snow and fog. The rain acidifies lakes and soils and corrodes buildings, while the nitrogen oxide and sulphur dioxide particles contribute to heart and lung problems. More acidic systems also tend to make mercury more available, and promote its uptake into the food web.

Aside from the lakes, acid rain also damaged the ground around them, leaching minerals like calcium and magnesium out of the soil, reducing the land’s ability to buffer the system. This was especially damaging in Atlantic Canada, where Kidd does most of her research, because the region’s many bogs meant the soils and waters were already naturally more acidic, so they started with even less neutralizing capacity.

“The chemical recovery happens fairly quickly, but the biological recovery lags behind.”

At the time, it seemed like an intractable problem. The vested industrial and economic interests involved were too strong, and the damage too severe to reverse.

“It seemed like a hopeless issue,” says John Gunn, a fisheries biologist at Laurentian University in Sudbury who has been studying the effects of acid rain for more than 30 years. “There were hundreds of damaged lakes, the complete collapse of the sport fishery.”

But a combination of scientific evidence and public pressure succeeded in forcing industry to clean up its act. The 1990 Clean Air Act Amendment in the United States and the 1991 Canada-U.S. Air Quality Agreement set strict limits on emissions and set up a cap-and-trade program to encourage companies to adopt cleaner technologies. The amount of acid rain falling in the U.S. and Canada dropped dramatically.

“It’s been a big success story,” says Gene Likens, an ecologist at the University of Connecticut who first discovered the effects of acid rain in 1963 at the Hubbard Brook Experimental Forest in New Hampshire. “At Hubbard Brook the acidity is now 80 per cent less than it was in the 1960s.”

Without new inputs of acid, many lakes and streams were able to return to their previous, more neutral, composition. But other parts of the ecosystem do not bounce back so easily.

“The chemical recovery happens fairly quickly, but the biological recovery lags behind,” says Rennie. So he is looking for ways to give it a boost.

Restoring the food chain

In the 1970s scientists acidified lake 223, at the Experimental Lakes Area in northern Ontario near Kenora, in an experiment to study the effects of acid rain on ecosystems. They found that while larger fish like lake trout weren’t directly affected by the lower pH, many of the things they eat, such as crayfish, fathead minnows and mysis shrimp, were wiped out, so the trout starved. Pictures of those starving trout were part of what helped to convince politicians to act on acid rain.

A healthy trout. Photo: IISD Experimental Lakes Area

A starving lake trout from acidified lake 223 at the Experimental Lakes Area. Photo: IISD Experimental Lakes Area

When the lake was restored to its natural pH level after the experiment, most of those prey species recovered. But not the mysis. Today, more than 30 years later, the trout in lake 223 are smaller, grow more slowly and have higher levels of mercury than those in neighbouring lakes, all because they don’t have the shrimp to eat.

“What if we put them back? Would it help the trout?” asks Rennie.

Rennie and his team are trying to answer that question. Each spring and fall for three years they will add 10,000 shrimp to the lake. Then, after waiting a couple of years to see if the shrimp can re-establish a breeding population, they will check to see if the trout are getting healthier. If so, restocking missing species could be a technique to help speed the recovery of other lakes affected by acid rain.

Because the lake is part of the long-term research at the Experimental Lakes Area, Rennie knows exactly what the ecosystem looked like before the lake was acidified, so he has a target to shoot for in restoring it.

“This is one of the rare instances where we know what used to be there, so it is okay to put it back,” he says.

Lake 223 at the Experimental Lakes Area in northern Ontario. The lake has been used to study the effects of acid rain. Photo: IISD Experimental Lakes Area

Not every lake’s history is as well documented as that of lake 223, though. So Rennie is also testing a method of reconstructing the past conditions for lakes without that documented history. He is looking at environmental DNA – the genetic traces left behind by long-dead organisms – in sediment cores from the bottom of the lake. If those match up with lake 223’s historical record, the same technique could be used to see into the past of other lakes, and figure out what creatures are missing today.

“We could use sediments to see what the lakes looked like before, and use that as our restoration target,” he says.

Fears of a backslide from increased emissions

It might prove impossible to return the damaged ecosystems to their historical state, of course. The loss of neutralizing minerals from the soil has left many in an extremely fragile state, Likens says, comparing it to someone with heartburn who has lost all of their Tums and Rolaids. Even a small amount of backsliding could undo 30 years of recovery.

“If we were to increase emissions again in these poorly buffered systems, the effects could be very large,” he says.

“When we were faced with what everybody described as irreversible damage, that proved not to be true.”

And in the decades since the lakes were ravaged by acid rain they have also been hit by another environmental disaster, climate change, which may mean it is not possible to get the ecosystem back to the way it was before.

“The climate may have changed enough already that it is no longer suitable for the organisms we want to bring back,” says Rennie.

The success of the efforts to control acid rain leave many scientists optimistic for the fight against climate change. The root cause of the problem — the burning of fossil fuels — is the same, and so are many of the solutions.

“We came together to make effective regulations and forced industry to adopt cleaner technologies, which made them more profitable,” says Gunn.

And the recovery shows that the earth has the resilience to bounce back from an insult, even if it might take decades, he adds.

“When we were faced with what everybody described as irreversible damage, that proved not to be true.”

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Six B.C. mines pose threats to Alaska’s most productive salmon rivers and should be investigated by the U.S. Secretary of the Interior, according to a coalition of conservation groups and Alaskan First Nations who are invoking legislation that says it is the Interior Department’s duty to investigate when foreign nationals may be affecting U.S conservation treaties.

A petition presented to Interior Secretary Sally Jewell suggests that B.C. mines close to the Taku, Stikine and Unuk watersheds diminish the effectiveness of two treaties that protect Pacific salmon, steelhead trout, grizzly bears and woodland caribou.

The treaties are the Convention for the Conservation of Anadromous Stocks in the North Pacific Ocean and the Convention on Nature Protection and Wildlife Preservation in the Western Hemisphere.

The coalition of U.S. and Canadian groups, including Earthjustice, the United Tribal Transboundary Mining Work Group, Sierra Club of B.C., Craig Tribal Association, Friends of the Stikine Society and Southeast Alaska Conservation Council, are echoing a previous call by Alaska’s congressional delegation to refer the transboundary mines controversy to the International Joint Commission.

DeSmog Canada wrote a series on the transboundary tensions stirred up by B.C.’s mining ambitions last year.

Kenta Tsuda, Earthjustice associate attorney, said the petition provides another reason for the U.S. federal government to take action.

“Canadian authorities are letting these projects go ahead and the U.S. government is still waiting on the sidelines,” he said.

The six mines that the coalition says are endangering the rivers are:

– The Tulsequah Chief, which has leaked acid drainage for decades;

– Red Chris, which is owned by Imperial Metals, the same company that owns Mount Polley (where the collapse of a tailings dam sent mine waste and sludge flooding into local lakes and rivers);

– Schaft Creek;

– Galore Creek;

– Kerr-Sulphurets-Mitchell (KSM), which will tap into one of the largest gold and copper deposits in the world; and

– Brucejack.

Frederick Olsen Jr., United Tribal Transboundary Mining Work Group chairman, said it is time for Jewell to become involved in the problem as the federal government has a fiduciary responsibility to the tribes.

“The development and operation of the B.C. mines could severely impact life on the U.S. side of the border,” Olsen said.

“Already the Tulsequah Chief Mine has polluted the Taku watershed for decades.”

The petition to Jewell says all the mines involve large-scale infrastructure development and generate immense quantities of tailings and mine wastes, meaning water treatment will be required in perpetuity.

“The threats of acid-mine drainage and heavy metals pollution — not to mention catastrophic dam failures — will hang over the watersheds for centuries after the closure of the mines,” says a statement from the group.

A spokeswoman for Jewell’s office said she is aware of the situation and the petition.

Tsuda said the petition is being submitted under the 1971 Pelly Amendment, which does not define a timeline for a response, but which makes it clear the agency is required to act within a reasonable time.

“In this particular case, Secretary Jewell should respond promptly by undertaking an investigation of the six mines we describe. Not only because we believe the circumstances legally obligate the agency to do so, but also because so much is at stake for communities in southeast Alaska,” Tsuda said in an e-mailed response to DeSmog Canada.

Salmon from the rivers support local fishing businesses and First Nations.

“Commercial fishermen from Southeast Alaska also rely on these harvests, harvesting tens of millions of dollars worth of salmon from these three rivers annually. The watersheds collectively support hundreds of Alaskan workers and their families,” he said.

There have been recent precedents where the Secretary of the Interior has stepped in, such as in 2011 and then 2014 when the department concluded that Iceland’s whaling activities were undermining worldwide efforts to conserve whales and diminishing the effectiveness of the Convention on International Trade and Endangered Species. The U.S. federal government then instructed agencies to undertake diplomatic action to encourage Iceland to change its policies.

Image of Mount Polley mine disaster by Global News

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