Mussels’ last meal; Scientists want to add bacteria that are lethal to invasive mollusks to water at Hoover or Davis dams, but they say tests will be done to ensure safety
Posted by: Aqua Blog Maven on June 20, 2008 at 6:30 amFrom the Las Vegas Sun:
They are so common they’re swimming in your spoiled milk, growing on the cheese left too long in the back of the fridge. But if bacteria were about to be released into your drinking water supply, would you worry?
The Bureau of Reclamation says you shouldn’t. Its scientists want to set Pseudomonas fluorescens loose at either Hoover Dam or Davis Dam (near Laughlin) this fall as a cavalry charge in what has so far been a losing battle against the invasive quagga mussel. Quaggas, which can clog water intakes and damage pumps and other machinery, hitched a ride from their native Ukraine to the Great Lakes about 20 years ago and were found to be infesting Lake Mead last year.
Water authorities and power plants now use chlorine and other chemicals to rid pipes of the clinging critters. But the quaggas can recognize the chemical as bad for them, and when they do, they close up and often avoid ingesting enough of it to kill them, according to Pam Marrone, founder of the California organic pesticide company working on an alternative.
There are other drawbacks to using chemicals against quaggas, including the detrimental effects on the environment. Chlorine and similar chemicals also can form cancer-causing carcinogens when combined with organic matter in the water supply, according to Peggy Roefer, regional water quality program manager for the Southern Nevada Water Authority.
Enter the bacterium that guards against root rot in the typical garden plot. Turns out it produces a toxin that kills the quagga, and its equally troublesome cousin, the zebra mussel. Mussels feed on the bacterium and don’t realize it’s deadly until it’s too late. Even dead Pseudomonas fluorescens kill the quagga, according to Dan Malloy, a research scientist at the New York State Museum in Albany who searched for the right bacterium for years.
He found the quagga killer to be harmless to several native fish and shellfish species tested, as well as to humans, Malloy said.
“We have been working with this bacterium for well over a decade. It’s everywhere. It’s already in the drinking water,” Malloy said, adding that his job is to work to preserve the environment, not pollute it. “I am a tree-hugger devoted to reducing the use of poisonous pesticides.”
In tests performed at New York power plants more than a year ago, the bacteria succeeded in killing up to 90 percent of zebra mussels and 70 percent of quagga mussels. And the bacteria may be even more successful at killing quagga and zebra mussels in the Southwest, because their kill rate is higher in warm, hard water.
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