Web Exclusive: Zebra mussel study takes high schooler to international science fair


TRAVIS COUNTY, Texas (KXAN) — A Lake Travis High School senior in Texas who researched a new way to kill zebra mussels in lakes is presenting his research at the International Science and Engineering Fair (ISEF) in Phoenix.

Jack Delli-Santi won both regional and state science fairs to reach the international competition with a project he started more than a year ago when he started scuba diving in Lake Travis.

“And you reach the bottom and there’s just a wasteland of mussels down there,” he said. “I’ve always seen signs for zebra mussels, but I’ve never seen anyone actually do anything about it.”

He decided he would do something, and started researching the invasive mollusks. Zebra mussels filter nutrients out of the water, depriving other organisms of what they need to thrive. Delli-Santi thought he could use the mussels’ gills against them, so he reached for a common food additive he was familiar with through his dad’s work as a biomedical engineer.

Carboxymethyl cellulose (CMC), also known as cellulose gum, is used as a thickener in various types of cooking, such as gluten-free baking. It remains viscous even when completely submerged in water, so Delli-Santi theorized it could effectively clog the mussels’ filters and kill them.

He liked the substance for other reasons, too: “It’s naturally biodegradable, it’s generally recognized as safe by the FDA, and it’s also biologically inert, meaning that it won’t affect the environment it’s placed into.”

Once he got the permits he needed to collect zebra mussels, Delli-Santi donned his scuba gear and, using a bucket and dive knife, scraped his test subjects off a buoy at Windy Point on Lake Travis.

Delli-Santi tested various concentrations of CMC, coating trays of zebra mussels he collected personally from Lake Travis and letting them sit for a few days. Higher concentrations, left to sit for six days, were the most effective at reducing the mollusks’ ability to filter water, killing them.

The top prize at ISEF, a contest among 1,800 students from 75 countries, is $75,000, and there are many other smaller prizes up for grabs. Regardless of what happens, though, Delli-Santi hopes to continue his research and turn his findings into a viable solution for the zebra mussel problem in central Texas.

“I’m hoping that something good will come of this,” he said, “because it’s definitely consumed a year of mine and I would like to see the community take a little more action against zebra mussels.”

His biology teacher, Kallie Nichols, has encouraged him along the way, accompanying him to the two science fairs he’s won and now to the ISEF as well. “He has just taken the bull by the horns, and I was mostly a cheerleader, honestly,” she said. “He’s actually got a provisional patent for this.”

But whether the method might be used in local lakes anytime soon is unclear. Brian Van Zee, regional inland fisheries director with the Texas Parks and Wildlife Department, said it’s an interesting idea, but he has concerns.

He hadn’t heard about Delli-Santi’s research until KXAN called, but among the reservations he brought up on hearing about it, is the potential cost of using CMC on a large scale. Delli-Santi found he could make 50 liters of an effective concentration of CMC for about $1.50, enough to seal off and treat an infested pipeline.

An open-water scenario would be more challenging, Van Zee said, due to the flow of water moving solutions around. It’s an issue TPWD encountered recently while trying to eliminate mussels from Sister Grove Creek north of Dallas. The department used potassium chloride and had to keep it in place in moving water for 48 hours. It was difficult to do, but the solution was effective, killing all but a few stragglers. 

Van Zee also said any new treatment would need to go through many levels of federal testing and approval, which would potentially take years. The department would also have to make sure the method wouldn’t kill native mussel species in the process.

That’s where Delli-Santi’s continued research might come into play. He’s been talking to a scientist in Michigan who’s been working with a specific type of bacteria that kill zebra mussels. “You could the CMC as a transport to put the bacteria directly where you want it, onto the mussels,” Delli-Santi said.

That way, the substance could be used in much lower concentrations and would not need to be present in the water as long. 

The rising college freshman plans to keep pursuing the research as he moves into the next phase of his education. “It’s followed me for this entire year,” he said. “It’s probably going to follow me into next year.”

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