Algae Blooms
In August, the abundance of algae blooms along prairie waters and beaches have become a growing nuisance. In an effort to tame the blooms, many regulators sought to limit nitrogen-based fertilizers. Interestingly, the limitation of such fertilizers actually causes the algae blooms to flourish. In his long-term study of thirty-seven years at Lake 227, David Schindler proved that restricting nitrogen has little effect on algae blooms. Instead, Schindler proved that it is the phosphorous content which controls algal growth. The unappealing blue-green algae merely fix nitrogen from the atmosphere and, therefore, the nitrogen content of the water is irrelevant. Restricting the amount of nitrogen actually succeeds in the increase of bloom size. The increase in blue-green algae proceeds to have detrimental effects on the food chain within the lakes as it is unfit for insect consumption. However, despite this knowledge, governments have recently focused on nitrogen restrictions due to the short-term experiments having shown positive results, contrary to the long term results presented by Schindler. Nitrogen and phosphorous limitations are currently suggested for Lake Winnipeg. While Alberta has proposed nitrogen usage guidelines to the public, it has yet to enforce them. The European Union is spending millions of dollars on nitrogen controls in an attempt to reduce the algal blooms of the Baltic Sea.
Reference
The Canadian Press. 2008. Algae blooms in lakes boosted, not cut, by nitrogen restrictions [online]. Available from http://www.cbc.ca/technology/story/2008/07/22/nitrogen-lakes.html [accessed 28 July 2008].
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Original text
Algae blooms in lakes boosted, not cut, by nitrogen restrictions
Last Updated: Tuesday, July 22, 2008 | 8:43 AM ET Comments24Recommend22
The Canadian Press
It's a familiar problem to prairie lake-lovers: yucky tangles of algae that make beaches and waters unappealing even on the hottest summer day.
Although some regulators are attempting to address the problem partly through restricting the use of nitrogen-based fertilizers, results from 37 years of experiments on lakes in northern Ontario show that reducing levels of the chemical just makes the problem worse.
"By cutting nitrogen, you get exactly the opposite of the desired result," said David Schindler of the University of Alberta, one of the co-authors of a paper published Monday in the Proceedings of the National Academy Sciences.
Schindler and his fellow researchers began experimenting on algae in 1971 by adding various quantities of nitrogen and phosphorous — two essential elements of fertilizers.
Over the years, they found that algae bloomed in proportion to the amount of phosphorous added. The availability of nitrogen, Schindler said, seemed to have little effect on how much of the green gunk grew.
"It didn't make any difference at all," Schindler said.
What was happening was that the blue-green algae that people find most objectionable were simply fixing nitrogen from the air, just as legumes do in farmers' fields. With unlimited nitrogen, and phosphorous taken from the lake water, that algae took over from other types.
"It actually intensified the blooms of these floating nuisance blue-green algae that people object to. Rather than cure the problem, it actually made it worse."
Affects food chain
Giving blue-green algae an advantage by limiting nitrogen affected the lake's entire food chain, because small animals like insects and snails can't eat it as they can other types of algae.
"They're untouchable as food," said Schindler.
Algae blooms are very common in prairie lakes, especially in August.
"(They're) rampant in the West," said Schindler, who has an international reputation for his work in freshwater ecosystems.
Schindler proved in the 1970s that phosphorous was the key factor in controlling algal blooms, a discovery that resulted in new regulations across Canada.
But he said that although there has been good evidence for years that the blooms can be successfully limited by focusing on phosphorous controls, there has been a recent trend for governments to look at nitrogen.
"Recently, there have been people making the same mistakes that we revealed back then."
In an effort to improve beaches at Lake Winnipeg, for example, engineers at the City of Winnipeg are proposing phosphorous and nitrogen restrictions, despite Schindler's results.
As well, countries in the European Union have spent hundreds of millions of dollars trying to end algae blooms in the Baltic Sea through nitrogen controls.
"We believe it's for no reason," said Schindler.
Nitrogen restrictions only show results in short-term trials, he said. The long-term results are demonstrated in his experiment, which studied the results over 37 years at Lake 227, a small lake in the Canadian Shield at the Experimental Lakes Area in northwestern Ontario.
Alberta does not regulate nitrogen use around bodies of water, but has suggested guidelines on the issue.