Texas

Energy and Environment Reporting for Texas

Invasive Zebra Mussels May Have Finally Met Their Match

Texas Parks and Wildlife's Todd Robinson holds a rock covered with zebra mussels in Lake Texoma, Texas. The mollusk can stick to nearly anything, posing problems for power plants and fishing boats.

Max Faulkner/MCT/LANDOV

Texas Parks and Wildlife's Todd Robinson holds a rock covered with zebra mussels in Lake Texoma, Texas. The mollusk can stick to nearly anything, posing problems for power plants and fishing boats.

At first glance, zebra mussels appear harmless, perhaps even cute. But the tiny creatures are anything but cute for Texas lakes.

Originally from Eurasia, zebra mussels made their first appearance in North America in the Great Lakes in the early nineties. The mussels have since made their way to Texas, and over the years, this invasive species has proliferated in the state, killing off alarming numbers of native species and clogging pipes used for power plants, drinking water, manufacturing and boating. Now they may have finally met their match, in the form of microscopic bacteria.

Currently, zebra mussels are combated with several strategies, including chlorine and metal-based solutions, filtering systems and hot water. But none have proven capable of wiping them out.

“There is not one silver bullet that is effective in killing the mussels in all situations that won’t harm other species and keep our waters safe,” says Brian Van Zee, from the Texas Parks and Wildlife Department.

Now Texas is looking into an up-and-coming pesticide that attacks zebra mussels and zebra mussels alone.

Daniel Molloy, a research scientist at the State University of New York at Albany, created a bacterium that gave way to an environmentally safe pesticide called Zequanox. Once Marrone Bio Innovations — a bio-based pest management company located in California — finishes commercializing the product, companies in Texas may buy Zequanox to rid their pipes of the invasive mussel, without harming native species. “In fact, the warmer the water is, we have seen in our tests, the more effective the kill is,” Molloy says.

Molloy's environmentally friendly pesticide may bring relief to lakeside companies.

Photo courtesy of New York State Museum

Molloy’s environmentally friendly pesticide may bring relief to lakeside companies.

The drawback?

The Environmental Protection Agency (EPA) prohibits treatment of Zequanox in open water and “unconfined infrastructure.” This means fishing boats, marinas and pipes exposed to open waters are off limits for Zequanox.

The EPA only allows use of Zequanox in enclosed water infrastructure, such as water storage chambers of power plants, pump stations, irrigation systems, industrial and manufacturing facilities and dams.

“A lot of lake associations are hearing about this product called Zequanox and they say, ‘Hey, we want to get rid of them from our lakes,’” Molloy says. “And I go, ‘Wait a minute.’”

He says for financial and technical reasons, “there is nothing on the market today that can be used to eradicate — eliminate — zebra mussels from a lake.”

Molloy says the only documented case in the world of a water body successfully eradicated of zebra mussels took place in Virginia 12 years ago.

“They took a quarry several acres large and on private land, and they took this fresh water quarry and they converted it into a saltwater quarry by adding a salt,” Molloy says. “But there was no outlet to contaminate any rivers.”

Eliminating the invasive species from a water body may be rare and unfeasible, but Molloy says it may be possible in smaller, “high value areas like a beach or a marina.”

Van Zee, TPWD representative, says Zequanox is still in the “developing stages, but it looks promising” for Texas. The US Army Corps of Engineers is currently researching the product as well.

If it ends up working, perhaps one day zebra mussels in Texas will be a thing of the past.

Comments

  • Dan Molloy

    Here are a few thoughts I would like to add this story.

    More info on my views on the potential for the use of the naturally-occurring bacterial strain that is now being commercialized under the product name Zequanox for zebra and quagga mussel control is available in a Commentary I wrote for the Minneapolis Star Tribune (http://m.startribune.com/opinion/?id=249354851&c=y). Bottom line is that I do not see any currently available control agent being feasible to use for highly effective control, much less eradication, throughout entire lake systems. Zequanox used in local high-value areas within a lake, like docks, beaches, etc., yes! But not throughout an entire lake. Nothing yet is.

    Yes, the treatment of a quarry in Virginia in 2006 with the salt potassium chloride remains the only successful example of the complete eradication of an established zebra mussel population that I am aware of. Potassium chloride does have a relatively low toxicity to aquatic organisms, except of course for mussels and other bivalves. If communities in Texas or elsewhere are thinking about using potassium chloride to similarly eradicate (completely eliminate) zebra mussels from their lakes, I caution that there would be very significant challenges in achieving that goal. There is an excellent discussion of these challenges in a document recently issued by the Iowa Department of Natural Resources that I highly recommend reading (http://www.iagreatlakes.com/2014/01/options-for-zebra-mussel-eradication-management). The document was produced in response to a request from the Iowa Great Lakes Association since zebra mussels were recently detected in their chain of lakes. The Iowa DNR document correctly emphasized that the successful eradication in the Virginia quarry would not be easily repeated in the Iowa Great Lakes because:
    — Application of potassium chloride in Virginia was feasible because of the absence of sensitive or imperiled native species in the quarry. In contrast, the chain of lakes that Iowa DNR was evaluating supports a diverse native ecosystem and several plant, animal, and fish species considered to be threatened, endangered, or of special concern, and the native mussel species in those lakes would be sensitive to the target concentration of potassium chloride used to kill the zebra mussels in Virginia.
    — In contrast to the relatively small (12-acre) Virginia quarry water body there
    would be a number of very significant logistical hurdles for application of potassium chloride in an attempt at whole-lake eradication. These included:
    1) lake stratification preventing mixing of the potassium chloride in the water column; 2) high water exchange rates diluting treatment dosage (the Virginia quarry essentially had no inlet or outlet); 3) the challenge of avoiding the creation of “hot spots” where potassium chloride concentrations temporarily would exceed target levels, thus potentially negatively impacting non-target organisms.
    — The Virginia quarry was on private land, thus making the application so much easier since there was complete control over any public access to the water body. A very comprehensive plan to ensure public safety and an action plan for the unintended release of concentrated potassium chloride would need to be developed if a public lake were to be treated.
    — Application of potassium chloride is not approved for use on water bodies used as a drinking water supply and thus governmental exemption for treatment would be required.

    The Iowa DNR document also mentioned that a treatment of a Texas creek in
    2010 with potassium chloride to stop the spread of zebra mussels downstream (http://www.dallasnews.com/news/community-news/collin-county/headlines/20100921-Texas-wildlife-officials-in-Collin-County-7515.ece)
    failed because the target concentration could not be maintained in the creek
    due to water flow.

    So sorry, there’s no practical method currently available to manage these pesty mussels in an entire lake or river. However, don’t give up hope for the future
    development of a variety of effective control techniques. Researchers like myself and my invasive-species-control colleagues continue to look for better and better ways to control these unwanted invaders, but this kind of research unfortunately can take a decade or more to come to fruition. Patience is a virtue.

    • mike hamblett

      Thank-you for taking time to write this very informative piece.

About StateImpact

StateImpact seeks to inform and engage local communities with broadcast and online news focused on how state government decisions affect your lives.
Learn More »

Economy
Education