The new microcapsules, which contain toxins that dissolve within a zebra mussel's digestive tract, offer a safe and cost-effective way of eliminating one of the world's "most important economic pests", without harming other aquatic life, according to scientists at the University of Cambridge.

The report, in the Feb. 1 issue of the American Chemical Society's Environmental Science & Technology journal, outlines how zoologist David Aldridge and colleagues developed microcapsules about the size of the algae particles that zebra mussels feed on. Once ingested, the "biobullets" slowly release small amounts of potassium chloride, a salt that is poisonous to most freshwater mollusks. Unlike other methods used to eradicate zebra mussels, such as chlorine, "biobullets" pose little or no threat to other marine animals, the researchers say, because they rapidly degrade and disperse in water.

Since their accidental introduction from Eastern Europe into the Great Lakes in the late 1980s, zebra mussels have become notorious aquatic pests, fouling water intake pipes at hydroelectric stations, nuclear power plants and industrial facilities.

In addition, zebra mussels can anchor themselves to other mollusks, making it impossible for native species to thrive. In some case, as many as 10,000 zebra mussels have attached themselves to a single native mussel, according to the U.S. Geological Survey (USGS). In all, the researchers note, coping with these pests costs upward of $5 billion annually.

Without many natural predators, zebra mussels have rapidly spread and are now found in 21 states including Oklahoma, Louisiana and Vermont, according to the USGS. Unchecked, many scientists suspect zebra mussels will soon spread throughout North American waterways.

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