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Mussel lab attracts graduate student to Missouri State

Tuesday, October 1, 2013

The Ozarks are known for natural beauty and especially clean streams ideal for outdoor adventures like fishing, camping and canoeing. Madeline Pletta, recent alumnus of the biology graduate program at Missouri State University, found that it is also a wonderful place to intensely study freshwater mussels with great faculty mentors, like Dr. Chris Barnhart.

“Dr. Barnhart can be considered the godfather of mussel rearing,” said Pletta.

After working a year and a half in Minnesota on a field survey team studying mussels in the Mississippi River, graduate school beckoned to Pletta, and the opportunity to work with someone like Barnhart drew her to Missouri State.

A place to call home

The lab is unique: it’s a captive propagation facility and a home both for mussels and students who study them. Pletta gained hands–on lab experience and led research projects on a variety of mussels, including the federally endangered pink mucket and invasive species like the zebra mussel.

The larvae of freshwater mussels are tiny, temporary parasites on the gills of fish, which are captured on fine screens after they leave the fish in the lab. Several hundred nearly microscopic juvenile mussels can be obtained per fish. These tiny juveniles grow to several centimeters in the Missouri State facility. Barnhart also has a mussel culture facility at the Kansas City Zoo where the animals are grown to larger size. The mussels are used for toxicology research as well as restoration of endangered species.

“Mussels from a pinhead to the size of your fist are raised at Missouri State and at the Kansas City Zoo,” Pletta said. 

Finding the perfect chemical balance

Barnhart’s lab was approached by Marrone Bio Innovations, a green pesticide company, to test the effect of its new biologically friendly molluscicide Zequanox on native mussels. Zequanox is used to control the zebra mussel, a non-native species that has become a pest in many parts of the world. This project became part of Pletta’s thesis research, to ensure that Zequanox does not harm native mussel species.

While mussels benefit the ecosystem as great bio filters, the invasive zebra mussel is hazardous since it can adhere to anything. One example Pletta noted was the ability for zebra mussels to clog pipes carrying cooling water in power plants.

The first stage of her research involved testing toxicity of Zequanox on four species of native mussels, one being the endangered pink mucket.  The tests showed that Zequanox has very little effect on the native species, indicating it is a promising product, she noted. Then she expanded her research to include seven species, researching their ability to capture different sizes of food particles.

Using a highly sensitive particle counter, Pletta released polystyrene micro-beads along with food into tanks of mollusks and tested the water at specific increments. As she watched, waited and tested, she found some surprising results.

“The overwhelming knowledge and literature out there says zebra mussels are excellent at clearing small particles and that native mussels aren’t,” she said. “Realistically, what I’ve seen is that natives are as efficient as or more efficient than zebra mussels at capturing the smallest particles when you’re taking the body size into account.”

Ultimately, her findings will be instrumental in determining the appropriate particle size and concentration for Zequanox, as well as allowing Marrone Bio Innovations to get Environmental Protection Agency approval for open water use of the product.


College of Natural and Applied Sciences
The College of Natural and Applied Sciences incorporates more than 20 undergraduate and 13 graduate programs along with one cooperative program offered through a partnership with Missouri S&T. The academic departments that make up the college include: biology; chemistry; computer science; engineering; geography, geology and planning; hospitality and restaurant administration; mathematics; and physics, astronomy and materials science. Students have the opportunity for intense hands-on research and internships through a number of outreach and research centers and work alongside faculty who are producing cutting-edge research in their fields.

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