Since their arrival in the United States during the mid-1980s, freshwater zebra mussels have practically topped the list of America's most wanted pests. The tiny molluskswhich crossed the Atlantic in the tanks of foreign shipsfirst settled in the Great Lakes but have now fanned out from the Mississippi River to Wisconsin's inland lakes. Wherever they go, they wreak havoc: the creatures suck in liters of water a day, depriving other indigenous marine animals of much-needed nutrients. They also lay their eggs near electric plant's intake pipes, fouling those systems for good.

New research presented at the annual meeting of the American Chemical Society suggests a novel way of eliminating these invaders. Although scientists have used molluscicides, chlorine and bromine to remove zebra mussels from certain lakes in the past, no one is certain what long-term environmental effects these chemicals might have. So Matthew Ryan, a chemist from Purdue University, and colleagues turned to low-energy radio waves instead.

The researchers exposed approximately 1,100 zebra mussels in large fish tanks to radio waves coming from a generator approximately a meter away. They found that all of the mussels died within 40 days. Among unexposed mollusks, only 10 percent died during the following weeks. The scientists further discovered that the tank holding the exposed animals contained four times as much calcium as the one that housed the unexposed mussels. "Zapping zebra mussels with these waves forces them to surrender essential minerals, such as the calcium they need to maintain their shells," Ryan explains.

Additional tests revealed that the waves had less effect on crabs, crayfish and other freshwater mussels and left fish entirely unharmed. The researchers are now planning to field-test the approach. "We can't get the zebra mussels out of the Great Lakes," Ryan adds, "but we can certainly prevent them from settling into intake pipes.