After reading a recent Star Tribune article about a new bacterial control agent capable of killing zebra mussels (“Heavyweight mussel fighters,” abridged from the New York Times, March 2), I examined the online readers’ comments. They had a lot of questions. Hopefully, I can provide some answers.
I know a lot about this control agent, since I invented it, and because my lab at the New York State Museum did two decades of research evaluating its effectiveness and safety before passing the baton to a commercial developer that gave it the product name Zequanox. Its active ingredient is a naturally occurring strain of a common microbe, the bacterium Pseudomonas fluorescens.
The Zequanox product contains dead bacterial cells. When a zebra mussel eats them, its digestive tract is disrupted by natural products inside the bacterial cells, leading to the mussel’s death. Since the bacteria are dead, once a treatment is made, the bacteria would not become established in a lake.
Safety trials performed at numerous labs have indicated that the specificity of this bacterium in killing zebra mussels (and their close cousins, quagga mussels) is extraordinary. No control agent, however, is perfect. It would be naive to think that a control method exists that has no risks whatsoever. As an environmentalist, I am pleased to see that researchers are continuing to define the safety of this bacteria-based product. My original goal when I started this project back in the 1990s was to invent a “green,” naturally derived control option for the zebra mussel problem. Thus, environmental safety is of the utmost importance.
Zequanox is now registered for use with the U.S. Environmental Protection Agency to clean these invasive mussels out of clogged pipes, thus reducing the use of potentially polluting chemical pesticides. Because of the size of lakes, however, it is quite unrealistic to think that it would be technically or economically feasible to use Zequanox or any other currently available method to control mussels throughout an entire lake. Zebra-mussel eradication (that is, 100 percent elimination) is even more unrealistic throughout an entire lake. No matter how environmentally safe and efficacious current formulations of Zequanox prove to be, I believe that lakewide applications will not occur. Efficacious use of Zequanox, however, in limited, high-value areas like bays, beaches, docks and marinas is definitely a possibility.
So should we all just quit and give up on trying to achieve economically feasible, environmentally sound, lakewide control of these tiny striped invaders? No. Definitely not. I gave a talk at the University of Minnesota this past fall that focused on this very point. But don’t hold your breath waiting for this research solution to arrive, because it is at least a decade away.
What will it look like?
Here’s what I envision:
I am convinced that there are “natural-born killers” of zebra mussels — lethal parasites that are extremely specific to infecting, reproducing in and ultimately killing zebra mussels. How would this control approach work? The zebra-mussel-specific parasites would be added to a lake, where they would be become established, then spread to other lakes on their own. Where are these natural-born killers now? They are in the native range of these mussels, in Eurasia, and my colleagues and I have been hunting them down for the last two decades. We’ve made progress in identifying some of these killers, but are still years away from finding the ideal candidate.
To say that this “natural-born killer” research project is daunting is a vast understatement. It’s like training to win the Olympic gold medal of pest control. With extraordinary hard work and a bit of luck, we might have a candidate in five years … and then it would be a minimum of another five years to comprehensively demonstrate its environmental safety — this latter goal being again of paramount importance.
So Zequanox may not be the perfect solution — the silver bullet that Minnesotans having been hoping for. But once its use in lakes is EPA-approved (which I anticipate this year), it should prove to be an effective and environmentally safe tool for use in a comprehensive program to fight off these invasive mussels in your land of 10,000-plus lakes.
Daniel P. Molloy is a research scientist at the University at Albany, State University of New York.