In March the New York Times published a story called “Science Takes on Silent Invader,” a version of which was reprinted in the Star Tribune. The article seems to indicate that scientists are closing in on a “silver bullet” solution, something that can be safely added to lakes that will kill zebra mussels and nothing else.
Unfortunately the article is misleading and the hope it generates unfounded. The article outlines the work of Dr. Dan Malloy with Pseudomonas fluorescens, a naturally occurring bacterium that kills zebra mussels. The bacterium is being marketed under the name Zequanox.
The public is justifiably excited about this discovery. Zebra mussels can threaten fisheries, lake ecology, and Minnesota’s $4 billion annual recreation-based economy, Mille Lacs being the most recent and painful example. Aquatic Invasive Species can lower property tax base and destroy public infrastructure like dams and water intake pipes at drinking water and hydroelectric facilities.
“The blogosphere and many newspapers have recently declared the war on zebra mussels to be won, but sadly those reports are grossly premature,” Jeff Forester, executive director of Minnesota Lakes and Rivers Advocates and member of the Statewide AIS Advisory Committee said.
“Yes, Zequanox can kill zebra mussels without harming other life, but it has an insurmountable obstacle of scale. There is simply no viable open water application,” Forester added.
Zequanox will kill ZMs in a pipe or tank with better than 90 percent effectiveness, and does not harm other creatures. But Zequanox is not a live bacterium, and so must be reapplied, which is cost prohibitive. If an inexpensive method of synthesizing Zequanox were to be developed, it would still be impossible to get concentrations high enough to treat even a small open water lake with currents, wind and waves.
Dr. Malloy is actively seeking funding of research building on his earlier work with Pseudomonas fluorescens, with an emphasis on trying to find a live organism that was self-replicating, could get federal approval, and would not harm any other aquatic life in the system. Dr. Malloy recognized that while his work to create Zequanox was like looking for a “needle in a haystack,” finding a similar live organism for open water treatments would be like initiating a moon shot and predicts an open water solution would take decades, if it was found.
“As we look for solutions to the state’s AIS problems we need to recognize that a combination of approaches that includes prevention and short-term fixes, as well as new science that aims for fundamental change with long-lasting effects is needed. This will take sustained effort and time,” said Dr. Peter Sorensen, the chair of Minnesota Aquatic Invasive Species Research Center.
There may never be a “cure” for the common cold or zebra mussels, but that doesn’t mean our lakes have to get sick. Instead we will need to enlist an array of strategies, behavior changes, tools and laws to continually lower the risk of transmission. Controlling AIS is about controlling the pathways on which they travel from one lake to another. The good news/bad news is that the great majority of these pathways rely on humans. We do have a certain amount of control. Zequanox may well play a role in this work, for instance as a treatment for ballast water tanks in wakeboard boats or in live wells and difficult to reach bilges, but Zequanox is no silver bullet.