Scientists puzzled by rising mercury contamination in some Great Lakes wildlife

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Editor’s note: Mercury contamination is one of the issues that will be discussed Oct. 11-14 in Detroit at the 2011 Great Lakes Week.  Detroit Public Television is providing ongoing coverage of Great Lakes Week at

Giant leaping fish, millions of mussels and a changing climate often push old school threats to the Great Lakes off front pages and minds.

But after decades of decline, mercury levels are increasing in some Great Lakes fish and birds, according to a recent study.

Some Great Lakes common loon populations were found to have increasing methylmercury levels. Photo: jackanapes (Flickr)

And health problems are occurring at lower concentrations than expected.

The study published in the journal Ecotoxicology examined recent research on mercury and, more specifically, methylmercury in fish, wildlife and their food webs in the Great Lakes region.  It is the most toxic form of the element and the only form that accumulates significantly in fish.

After years of decline, methylmercury levels are again rising in some species.

“Overall things remain encouraging, but we’re seeing trend reversals in some species,” said James Wiener, professor at University of Wisconsin-La Crosse and study coauthor.  “We observed increasing levels in common loons in Wisconsin, walleye in Ontario, Minnesota and Lake Erie, and northern pike in Minnesota.”

The study didn’t pin down why methylmercury is increasing in these species.  Whatever the cause, it is happening from the bottom up, Wiener said.

“We suspect something is happening regionally or globally to increase the concentrations at the base of the food web.” he said.

At each step in the food chain, the concentration of methylmercury in organisms increases, Wiener said.

The study also found lower levels of mercury and methylmercury are causing harm at levels once not thought to be dangerous.

“We now realize effects and risks have increased in fish and wildlife because they’re occurring at a much lower level,” Wiener said. “And the same thing goes for humans.”

In the common loon, for example, exposures that cause no effect in the adults can impair egg fertility, survival of newly hatched chicks, and overall reproductive success.

Mercury can harm the brain, heart, kidneys, lungs and immune system in humans.  Women who may become pregnant and young children are the most at risk.  According to the study, between 300,000 and 600,000 children are born in the U.S. each year with enough mercury to harm brain development.

Eating fish is the most common way for humans and wildlife to be exposed.

All Great Lakes states have mercury fish consumption advisories. Photo: EPA

All of the Great Lakes states warn people to limit how much fish they eat because of mercury contamination.

The element occurs naturally but is often introduced into the environment through human activities — burning coal or waste are the two largest sources.  Coal-burning power plants are the largest human-caused source of mercury emissions to the air in the United States, accounting for more than half of all human-caused emissions, according to the Environmental Protection Agency.

In 2010,  Great Lakes government officials developed a strategy to reduce mercury.   It is a partnership of federal and state agencies, Great Lakes governors, mayors and tribes.

All eight Great Lakes states are implementing the voluntary recommendations, said Debra Jacobson, regional operations manager with the Illinois Sustainable Technology Center and coordinator of the reduction strategy team.

The recommendations include reducing emissions from power plants and waste incinerators, and getting mercury out of products.  States are getting mercury out of products first, Jacobson said.

“It’s a priority pollutant that’s not going away,” Jacobson said.  “But use and emissions are on the decline because states are taking these recommendations.”

And while there’s been a steady decrease in mercury emissions since the mid-1980s, there’s still a lot of work to be done, Wiener said.

“Efforts to reduce emissions are going to produce results,” he said.  “But we’ve learned that we need to get concentrations even lower than previously and figure out why there’s some trend reversals.”

9 thoughts on “Scientists puzzled by rising mercury contamination in some Great Lakes wildlife

  1. puzzling? how?
    GET RID OF ALL THE COAL FIRED POWER PLANTS BEFORE ITS TOO LATE…where all we will be able to do is view the lakes-not swim fish boat or enjoy them…at least until we humans are dead and gone.
    and i am just a layman…

  2. Pingback: Scientists head to D.C. with mercury findings | All Kinds of Wind

  3. Pingback: Scientists head to D.C. with Great Lakes mercury findings « Ohio Citizen Action

  4. Pingback: Scientists puzzled by rising mercury contamination in some Great Lakes wildlife « Environmental News Bits

  5. Dealing with pollution and other environmental problems clearly USED to be nonpartisan. Most of our greatest environmental laws were passed in the early 1970s under Republican administrations. But the Republican Party has turned away from those conservative values. In doing so, I have turned away from the Republican Party, even though I continue to be a staunch fiscal conservative. But, I don’t have much good to say about some Democrats either. The worst of them also subscribe to a faulty notion that environmental health and economic prosperity can’t coexist. They, too, have become shills for multi-national corporations that don’t always have our best interests at heart (to say the least). Corporate lobbyists in this country have greatly contaminated our political system but, in all fairness, they seem much more aligned with Republicans these days–and to a lesser extent with Democrats. I make this observation as a former Republican. Of course Republicans DON’T deserve ALL of the blame, but any objective observer would admit that they should take their share of it. As for our national debt, we need to get rid of it (which neither Republicans or Democrats seem inclined to do), but I think our greatest deficit to be concerned about is the one we’re creating in nature. Worldwide, we have a tremendous “nature deficit disorder” going on and no politician seems to be taking a lead on dealing with it–Republican or Democrat.

  6. In the pacific northwest and alaska they found where the salmon all die in the spawning areas enmasse, there’s a 25 fold increase in mercury levels. The salmon swim around collecting it, and deposit it in concentrated form. It has to be happening here, it’s just not studied. There was one brief mention in a Muskegon river Walleye study, which led me to google the salmon mercury. All fish have mercury, salmon are the only ones that all die in one spot at the same time.

  7. Mercury is a nonpartisan toxic contaminant. We know what the largest sources are, and know they need to be cleaned up. Reducing our dependence on coal will go a long way to reduce mercury in our water, our fish and our growing children’s bodies. It will also foster innovation in renewable energy source and move our energy strategies into the 21st Century. Good for people, good for global leadership, and really, really good for loons, fish and other innocent storehouses of toxic pollution from the skies.

  8. Your partisan rhetoric is almost as humorous as it is misguided. So, to continue your train of thought: While Republicans continue to wish for heavy drinking water, Democrats continue to think that borrowed dollars absorb mercury.

    Keep buying into the Kabuki.

  9. Why should this be a surprise? The new mantra of the Republican Party is to weaken environmental protections at every turn so corporations can spew more toxics into our air, water and land. They think it will boost the economy (sic).

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