SUPERIOR, Wis. (AP) -- A research center located on Lake Superior is helping figure out the best way to kill the invasive species that often hitchhike in ballast tanks of giant cargo ships.

On-board ballast water treatment systems are seen by many as a solution to the problem of invasive species in the Great Lakes. But the treatment systems have to be tested first.

A research program called the Great Ships Initiative uses a lab at the University of Wisconsin-Superior along with a testing center on the lake where pipes and tanks mimic a ship's ballast system, which is used to help keep a ship balanced before it takes on cargo.

The treatment systems use everything from ultraviolet light to sound waves to ozone to kill organisms that might otherwise harm the Great Lakes ecosystem.