JUNK FOOD FOR FISH
Pollution Altering Alpine Lakes
Those remote mountain lakes aren't so remote after all.By David Frey, 11-10-09
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| Twin Lake in Colorado's Rocky Mountain National Park. | |
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What seem to be pristine alpine lakes high in Colorado’s Rocky Mountain National Park are getting greener, and not in a good way.
A report in the current edition of Science finds that those lakes are being swamped with nitrogen from the atmosphere, caused by pollution from cars, factories, feed lots and fertilizer. The nitrogen is essentially fertilizing lakes that aren’t used to being fertilized, causing a growth of algae and threatening to harm the fish at the top of the food chain.
In addition to our carbon footprint, researchers say, human activity leaves a more subtle nitrogen footprint that is affecting natural systems around the world, even in some of the most remote places.
“It’s part of a global phenomenon,” says James Elser, life sciences professor at Arizona State University, the lead author of the report.
The increase in nitrogen has caused so-called “dead zones” each summer in the Gulf of Mexico and around the country, where algae blooms consumes the available oxygen and starves aquatic life off the coast. Researchers say a similar phenomenon is occurring in alpine and subalpine lakes in Rocky Mountain National Park, and at remote lakes in Sweden and Norway. Parts of the world that seemed far-removed from human impacts are being affected by a doubling of nitrogen released into the earth’s atmosphere since the Industrial Revolution.
“This is as serious a problem (as global carbon levels),” says co-author Jill Baron, ecosystem ecologist for the US Geological Survey’s Natural Resource Ecology Laboratory Colorado State University. “What we have is nitrogen that’s up in the atmosphere with the prevailing winds and it comes down in rain and snow. It’s fertilizing places that have never seen it before.”
Nitrogen is released into the atmosphere from tailpipes, industrial operations, cattle manure and artificial fertilizer. High-alpine lakes have historically been low in nitrogen. When nitrogen pollutes the lakes, it causes microscopic phytoplankton to become deficient in phosphorus, which is needed for the plants to grow properly. That can mean more—but less nutritious—algae in the lakes for the animal plankton to feed on. When the fish eat the animal plankton, they don’t get the proper food either.
“It’s junk food for fish,” Elser says, “like expecting a teenager to grow by just eating marshmallows.”
The algae bloom can also contribute to greenhouse gases, Baron says. The additional plant growth often ends up dying, floating downstream and putting more carbon into the atmosphere.
“We have disrupted the global nitrogen cycle and few ecosystems if any are immune from this,” says Baron, who will address the upcoming climate talks in Copenhagen. “Even very low amounts of this nitrogen that comes out of the sky can cause major changes to protected ecosystems. ... One of the nice things that I think we have in our grasp is our ability to reverse it. None of this is permanent.”
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Comments
I fail to see why the author would write; "...are getting greener, and not in a good way." Is it just more hype? Maybe we should attack all life-sustaining elements. Afterall, Hydrogen and Oxygen are the only other's that haven't been vilified.
Ocean species would die without salt, but it can kill freshwater species. Same with nitrogen. Hydrogen and oxygen are fine, too, as long as you don't try to breathe the two of them together. Then they're not life-sustaining anymore - unless you're a fish.
Nice quips about compounds, too. NaCL and H2O. Good ones. I may not want to breath H2O, but I will continue the risk of drinking it, thank you.