Low-frequency radio waves might someday be used instead of chemicals to control zebra mussels that cause millions of dollars in damage by clogging water intake pipes, researchers said.
Zebra mussels in an aquarium that were exposed to very low-frequency electromagnetic waves - around 60 hertz, or similar to what is emitted by a power outlet - died within 40 days, according to a study conducted by undergraduate students at Purdue University-Calumet in Hammond, Ind., and presented at an American Chemical Society meeting in Chicago.
Though field trials still must be conducted, the technology appears promising, said Matthew F. Ryan, associate professor of chemistry at Purdue. The technique appears to be safe for fish and other aquatic life, he said.
Chemicals such as chlorine and bromine have been used to kill the mussels, but there are concerns about the safety of the substances, Ryan said.
Brought to the United States in the ballast water of oceangoing ships in the 1980s, zebra mussels spread rapidly through the Great Lakes and other inland waterways and have caused millions in damage to power plants and boats.
Gary Wege, a biologist with the U.S. Fish and Wildlife Service in Minnesota, welcomed the study, saying that most efforts to control zebra mussels have failed.
``If you could zap the critters right from the water, that would be great,'' Wege said.
If the technique proves effective, Wege said, electrical barriers could block the mussels from infesting other waters.
Ryan said irradiation appeared to cause zebra mussels to lose large amounts of calcium - essential for shell health and muscle control - as well as sodium and potassium. Only 10 percent of unexposed mussels in another tank died after 40 days, he said.
During experiments, fish collected from the same waters and put in the same tank as the mussels survived. Native clams did not die until being exposed for 90 days.
Ryan said the technology would have to be installed in intake pipes and the radio waves aimed at specific spots.