Researchers Say Non-Native Earthworms Pose Risk To Ecosystems On One Of The Channel Islands

Feb 13, 2017

It sounds ominous. An army of invaders has infested one of the Channel Islands.

It’s “The invasion of the earthworms.”

Okay, so when you hear that it’s earthworms, it doesn’t sound quite so ominous.

But, the invasion by the non-native worms is creating big concern, because it’s disrupting San Clemente Island’s unique ecosystems.

Dr. Travis Longcore is a spatial scientist at USC, and is part of a team than conducted a two year study on the earthworm problem. San Clemente Island is the southernmost of the Channel Islands. The 56 square mile island is owned and operated by the U.S. Navy, which uses it for everything from flight training to Navy SEAL drills.

But, the island, which isn’t open to the public, is largely untouched, and contains some archaeological artifacts dating back some 10,000 years. The Navy commissioned the earthworm study, over concern the non-native creates would disrupt the native habitat, including the archaeological sites. There’s also concern that long term, they could disrupt the island’s unique biodiversity, because they alter the soil.

The researcher says it’s believed the earthworms were accidently brought to the island as part of a construction project several years ago. There’s no way of telling how many of the worms now call the island home, but without native predators to at them, they have flourished, and spread. Longcore says while concern is high about the damage they may cause, there’s no practical way to get rid of them.

The researcher says one of the big lessons is that island managers have to be cautious about what’s transported to the Channel Islands. Island managers are much more cautious now about what comes into the islands, to try to insure there aren’t more invasive hitchhikers.

The study done in conjunction with Dr. Scott Loss at Oklahoma State University is now complete, with two papers published on the research, and a third still pending. Longcore says it would be interesting to do more research to monitor what impacts the earthworms are having on the island’s environment, and how much they are continuing to spread.