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A DAILY dose of radio waves may help destroy invasive zebra mussels, the tiny
freshwater molluscs from Europe that are clogging up the waterways of North
America.

Zebra mussels are native to the Baltic countries and Russia, and only reached
the US and Canada in 1988. Unfortunately they thrived in their new habitat and
spread rapidly throughout the Great Lakes region. Now the mussels are blocking
water intakes at power plants and factories, damaging docks and clogging boat
motors. They are also outcompeting native mussels for food.

But Matthew Ryan of Purdue University Calumet in Hammond, Indiana, thinks he
has found their Achilles鈥� heel. Exposing the zebra mussels to extremely
low-frequency radio waves makes their body chemistry go so badly awry that they
die within weeks. In lab studies, mussels exposed to radio waves of up to 300
hertz for a few hours will close their shells in a stress response. Over the
next few days, the mussels start to lose calcium from their shell. After 20
days, more than half will be dead. This technique might cut the use of toxic
chemicals such as chlorine now needed to control them, Ryan told the American
Chemical Society meeting in Chicago last week.

Ryan thinks the mussel鈥檚 weakness is its inefficient metabolism that requires
it to filter vast amounts of water鈥攐n average 1 litre per mussel per day.
The radiation may stress the creatures, causing them to filter less water, which
in turn means that the calcium they release is not replenished.

Susan J. Nichols of the US Geological Survey鈥檚 Great Lakes Science Center in
Ann Arbor, Michigan, cautions that field trials could produce very different
results, but 鈥渋f it works in the field, it would be absolutely wonderful鈥�.