Scientists developing new method of curbing invasives in Great Lakes

Discharging ballast water
Ballast water is discharged from a ship in a file photo. Scientists have wrapped up three years of research on a new method of cleaning ballast water, which can carry invasive aquatic species.
Photo courtesy of the U.S. Geological Survey

Federal scientists are one step closer to developing a new way to treat ballast water in ships on the Great Lakes in a effort to prevent the spread of aquatic invasive species.

Scientists have wrapped up three years of research on a new method that uses sodium hydroxide to kill zebra mussels and other species that are transported in ballast tanks. Then carbon dioxide is used to clean the water before it's released.

Phyllis Green, the superintendent of Isle Royale National Park, is spearheading the research for the National Park Service.

"What we're doing is we're using the ballast tanks themselves as a holding tank, both for treating them with an active biocide designed to kill the organisms inside the tank, but also then we're treating the biocide after it's done its job with the organisms, to neutralize it before we release it," she said. "Basically we want to kill as much as we can but still be able to release back into the environment benign water that won't harm the resident fish or animals."

Shore tests done in Lake Superior using this method have killed nearly 99 percent of invasive species. Results from this new test will show whether the process also works on an actual ship.

More than 60 percent of invasive species introduced in the Great Lakes have come from ballast water discharged by ocean-going ships. Green hopes ships will use this new method of treating that water within the next two years.

Invasive species cause an estimated $5.9 billion in damage to the Great Lakes every year.