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Can Zequanox end the era of malicious mussels?

Scientists from the New York State Museum documented zebra mussels suffocating native clam species in June 2013. (Photo contributed by NYSM)

Buzz has been circulating that another Zequanox trial is planned for a Douglas County lake this summer. It's true.

In 2012, a mobile laboratory trial was conducted on Lake Carlos. The 2013 study planned for Little Lake Darling will determine how effective Zequanox can be at saving native clam species from zebra mussels.

Denise A. Mayer, director and senior research scientist with the New York State Museum's Field Research Laboratory (NYSM-FRL) in Cambridge, New York is working on a U.S. Environmental Protection Agency (EPA) project in collaboration with the United States Geological Survey (USGS) out of La Crosse, Wisconsin and in cooperation with the Minnesota Department of Natural Resources. Scientific teams visited Douglas County and scoped out a prime location during a scuba dive expedition in June.

"Lake Darling had both clams and zebra mussels," Mayer said. "Carlos had zebras but the clams were already dead."

Jim Luoma, study director with the USGS said the test on Lake Darling will be conducted this summer. A timetable is contingent on weather but could begin as early as the end of July, Luoma said.

Originally, Lakes Cowdry, Taylor, Stony and Union were proposed for the experiment. However, none had the proper composition of clams and zebras mussels.

Mayer described Zequanox as a natural product used to eliminate the threat of zebra mussels. The NYSM-FRL developed Pseudomonas fluorescens strain CL145A, the active ingredient in Zequanox. Mayer has been with the project since 1995.

"This product is safer than many things we consume."

Jim Luoma, Study Director, United States Geological Survey


The 2013 trial involves quarantining off five-foot square sections in Lake Darling where zebra mussels are prevalent. Plastic sheeting will be inserted into the lake in depths of up to five-feet of water. Zequanox will be added to six of nine control units while inside a plastic membrane.

Some people are wary of the next step in the process - returning the zebra mussels to the lake and removing the plastic walls separating the controlled environments from the rest of the lake water, thus releasing Zequanox into the local aquatic habitat. Mayer attests that Zequanox is not active 24 hours after application.

In a letter to the Cowdry, Taylor, Stony and Union Lakes Association (CTSULA), Mayer wrote that the goal of this year's trial is to demonstrate whether treatment with Zequanox will effectively remove zebra mussels from native clams to ensure the clams' survival.

Zebra mussels have been suffocating clams, which kills a vital part of the ecosystem. Clams dig down into the sediment and provide oxygenation to water bodies. Mayer said native clam species in North America are endangered.

"Since zebra mussels have come into waters, they've become the biggest threat [to clams]," Mayer said.

CTSULA is researching the use of Zequanox and consulting professionals before making its opinion public. Members were notified of the 2013 research project when their lakes were being considered.

"We have not taken a stand as an association at this point," said Peggy Olson with CTSULA.

Luoma said a lot of people are confused about Zequanox. "It's a killed cell, it can't be infectious," Luoma said. "This product is safer than many things we consume."

Luoma directed the 2012 study on Lake Carlos.


People hear the term biopesticide associated with Zequanox. The product has a Materials Safety Data Sheet (MSDS) with the EPA. Personal protection equipment is recommended when handling the bacteria in powder form. But is it dangerous?

"No more dangerous than dust," said Sarahann Rackl, director of water technologies for Marrone Bio Innovations (MBI). "Even when people are cleaning their yards in the fall, it's recommended to wear a mask."

Mayer said that it's the terminology that trips people up when it comes to biological based products, that chemicals are so common that people automatically think Zequanox is a chemical.

"It's probably the most common species of bacteria in the world."

Denise Mayer, Senior Research Scientist, New York State Museum-Field Research Laboratory

Mayer explained that unlike a chemical, Pseudomonas fluorescens is a naturally occurring bacteria. Zebra mussels eat the bacteria and are killed by a reaction that occurs after consuming the product. A mussel would not ingest a chemical, it would just close up, Mayer said.

Initially, Zequanox was developed as an environmentally friendly agent for power plants to use in cleaning zebra mussels from pipes. The NYSM-FRL scientists were concerned with the use of poisons such as bleach and cancer causing agents for pipe cleaning, which led to the screening for a biological alternative. The strain of Pseudomonas fluorescens is a bacteria that occurs naturally in North America.

"It's probably the most common species of bacteria in the world," Mayer said. "In truth, a low percentage of bacteria are bad. We need bacteria."


Zequanox's MSDS rates the material as "Stable." It is tan in color and has a sweet, musty odor. The label also says it is not expected to bioconcentrate in organisms.

Mayer said Zequanox is degraded within 24-hours of being applied to water and toxicity trials have demonstrated safety to other fish and mussels at the highest concentration tested.

Although representatives of the NYSM-FRL have said Zequanox use has demonstrated safety to other fish and mussels, EPA documents precaution that the product is hazardous to humans and domestic animals if inhaled.

Rackl said "harmful to humans and domestic animals if inhaled" is standard EPA language for all dry or potentially dust-forming products, adding that MSDS are written for workers who handle the product in raw form and are regulatory. Luoma agreed with Rackl, stating that even baking soda has an MSDS.

"It's part of nature. We're looking at nature to solve nature's problem."

Sarahann Rackl, Director of Water Technologies, Marrone Bio Innovations

MBI acknowledges on Zequanox's MSDS that the product may be irritating to skin, eyes and respiratory tracts of some individuals, while maintaining that the product has "very low toxicity by ingestion, skin contact or inhalation." Zequanox's toxicity was tested on rabbits and rats. Irritation and skin sensitization was measured in rabbits and guinea pigs, according to the MSDS.

Rackl cited the EPA's position on Zequanox as: "Determination of safety to the general population, including infants and children: The use pattern of application to water at a dilute rate and the lack of toxicity noted from oral, dermal, inhalation and eye exposures indicate that there would not be any significant hazard posed to sensitive populations from exposure to Pseudomonas fluorescens MOI-401."

The EPA label for Zequanox also states that discharging effluent containing the product into lakes, streams, ponds, estuaries, oceans or other waters is an environmental hazard unless done in accordance with the requirements of a National Pollutant Discharge Elimination System permit.

Luoma said the group is working closely with the DNR and assures all proper permits are in place. Applications of Zequanox must be used under the supervision of MBI.

MSDS data from April 2013 lists Zequanox as nontoxic or practically nontoxic to mammalian and avian wildlife. Zebra and quagga mussels are affected by the product while it poses a low toxicity to freshwater fish, native mollusks, insects, plants, crustaceans and other aquatic organisms.

People can swim in, eat fish from, irrigate crops with and even drink water that has been treated with Zequanox.

"It's part of nature," Rackle said. "We're looking at nature to solve nature's problem."

Read article on Lake Carlos study Lake Carlos zebra mussel study produced results.

DeyCrystal Dey Crystal Dey is a staff reporter for the Echo Press. Originally from Minnesota's Iron Range, Dey worked for newspapers in North Dakota, Florida and Connecticut before returning to her home state to join the Echo Press in October 2011. Dey studied Mass Communications at Minnesota State University Moorhead with an emphasis in Online Journalism. Follow Staff Reporter Crystal Dey on Twitter at @CrystalDey_Echo.

Crystal Dey

Crystal Dey is a staff reporter for the Echo Press. Originally from Minnesota’s Iron Range, Dey worked for newspapers in North Dakota, Florida and Connecticut before returning to her home state to join the Echo Press in October 2011. Dey studied Mass Communications at Minnesota State University Moorhead with an emphasis in Online Journalism. Follow Staff Reporter Crystal Dey on Twitter @Crystal_Dey.

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