An Iowa State University researcher’s come up with an inventive solution to fight off alien invaders. In this case the invaders are plants and animals that don’t belong here, and scientist Hans van Leeuwen is an environmental engineer who’s studied how big cargo ships and small boats carry those “exotic species” to parts of the world where they don’t belong. Invasive species can be things that live in water or on land, but are life forms that may live in a similar climate but wouldn’t normally have come here on their own. With no natural enemies, the scientist explains a new weed, bug, animal or bird can overpopulate its new region and cause all kinds of problems. One of those species is a tiny clam called the zebra mussel, which van Leeuwen says arrived in the Great Lakes via ocean-going cargo ships and was carried to inland waterways including the Mississippi River in Iowa. The compete with other mussels and crowd out the existing larger species of clams. That’s just the ecological damage: financially they’re a headache, too, as they attach their shells to the intake pipes for city drinking-water systems and power-plant cooling systems. By blocking the intake pipes, they cause enormous economic damage. The researcher says they’re looking at a cost between five and fifteen-billion dollars from the zebra mussels in the Great Lakes area of the north-central U.S. They can’t poison Lake Superior or the whole Mississippi River to get rid of the hard-shelled pest, but the ISU scientist has come up with a plan to “gas” them.He uses ozone, which he says is a very good disinfectant for coping with invasive species. He says ozone will work on other invasive species that infest waterways, too, and it quickly dissolves leaving no poisonous or hazardous residue.