Cargo ships that cross the oceans often end up transporting more than goods for sale. Invasive species can hitch a ride in a vessel’s ballast water. But now researchers have found a new way to get rid of unwanted stowaways before they disrupt local ecosystems, according to a BBC News story.

Ballast tanks fill with water when a ship’s cargo is unloaded, keeping the ship stable and upright. Then, when the cargo holds are refilled, the ballast tanks jettison water they were holding — along with whatever creatures may be living inside.

Like Your Microwave

Researchers at the Louisiana State University Agricultural Center say in a study that microwave heat is an effective way to kill stowaway species before they can cause harm to marine ecosystems.

Dr. Dorin Boldor, a co-author of the study, explains to BBC News:

“The basic idea is that you take the ballast water and pump it through a microwave cavity.” He added that the system would follow the same principle as a household microwave oven.

“The power level is much higher and a different frequency, but it creates a very high intensity electric field in the centre of the cavity that oscillates rapidly…”

The friction created among the water molecules causes enough heat to kill alien invaders.

The Culprits

While the UN’s Global Ballast Water Management Program advises that more than 7,000 species can be transferred in ballast water, only some of them find their new environment hospitable.

For example, European zebra mussels are said to have arrived in the US in the ballast tanks of ships. Now they have taken over almost half of inland waterways here.

To learn more about the serious environmental and human impacts invasive species can cause, visit “Animals Behaving Worse” on NATURE Online. Find out why the zebra mussel is among the Top 10 Least Wanted Species, and discover other pesky creatures (like the bed bug) that have spread across the globe.