Fighting Aquatic Invasive Species

In the summer of 2013, a team of Nature Conservancy and Notre Dame researchers found something unsettling in Calumet Harbor: two environmental DNA (eDNA) samples that tested positive for the DNA of Eurasian ruffe, an aquatic invasive species (AIS) currently threatening to invade southern Lake Michigan and the Mississippi River basin.

Like many of the crime labs in today’s most popular TV shows that use DNA to tie the criminal to the crime scene, our experts are using eDNA as a surveillance tool to monitor for aquatic invasive species, which damage local wildlife populations and cost the economy of the Great Lakes region hundreds of millions of dollars annually. Because all fish shed DNA material into the environment through mucus and excrement, this technique detects the presence of different species through the collection of water samples that are filtered in the lab and analyzed for target species’ DNA.

The Eurasian ruffe findings are not the first time that the team’s eDNA science has alerted researchers to the possible presence of aquatic invasive species in our waters. In 2009, eDNA samples tested positive for Asian carp in Lockport and Brandon Road locks and dams in the lower Chicago Area Waterway System (CAWS)—directly downstream of the electric barriers built to prevent Asian carp entering the Great Lakes. These positive eDNA results preceded the first live capture of bighead carp in the Lockport pool in December 2009. Subsequently, eDNA for Asian carp species was detected above the electric barriers in 2009 and 2010 throughout much of the CAWS, including Calumet Harbor in Lake Michigan, and then more recently at sites in Lake Erie and also Sturgeon Bay in Green Bay, Wisconsin.

While positive eDNA results like these are not good news, they do have a silver lining. Surveillance techniques of the past had a limited chance of detecting new introductions while populations were still small and vulnerable. eDNA makes early detection possible. For example, the discovery of Asian carp eDNA above the barriers in late 2009 and 2010 ultimately prompted the Asian carp regional response and over $200 million in investments for new control tools, response planning, control and monitoring efforts by government agencies.

The hope is that the most recent Eurasian ruffe eDNA findings, which shortly preceded the release of the U.S. Army Corps of Engineers’ Great Lakes Mississippi River Interbasin Study (GLMRIS), will guide regional stakeholders to join forces and take action to protect both the Great Lakes and Mississippi from the spread of AIS. The GLMRIS is an assessment to identify potential solutions to prevent the passage of AIS through the CAWS to the Great Lakes or Mississippi River basins.

“All of this mounting scientific evidence demonstrates the very real economic and environmental threat these organisms pose to Illinois, the Great Lakes, and downstream Mississippi basin states. We must take action now; we cannot afford to wait,” said Illinois State Director Michelle Carr.