(12/22/25) BATON ROUGE, La. — Beneath the surfaces of rivers, lakes and ponds throughout Louisiana, freshwater mussels work to improve water quality and build habitats for other aquatic species, research shows.

While these important bivalves perform crucial ecosystem functions in numerous Louisiana streams, they remain undervalued and at risk, said Garrett Hopper, an assistant professor of aquatic ecology at the LSU AgCenter.

More than half of Louisiana’s freshwater mussel species are considered critically imperiled, imperiled or vulnerable by the Louisiana Department of Wildlife and Fisheries, and five species are listed as threatened or endangered by federal agencies.

“Our goal is to figure out how to protect them and manage them so that they can basically keep doing what they’re doing to make our water healthier,” Hopper said.

Hopper’s fish and mussel ecology lab in the School of Renewable Natural Resources focuses on freshwater fish and the bivalves while educating the public about many lesser known, yet significant, species. While scouring the state’s waterways, Hopper and his student researchers can be found distributing “mussel propaganda,” as Hopper calls it, such as educational posters and booklets.

The most recent outreach publication, Freshwater Mussels of Louisiana: A Field Guide, was published in December after nearly two years of work by Hopper and undergraduate researcher Franchesca Ruiz.

Hopper said the 84-page booklet was 95% of the vision of Ruiz, who became fascinated by mussels during an introductory class in the School of Renewable Natural Resources. She completed much of the work on the project as an intern in the LSU AgCenter ASPIRE program, which helps undergraduates earn hands-on agriculture experience and is funded by a U.S. Department of Agriculture grant.

“These animals have a really special place in my heart,” Ruiz said. “They’re so amazing once you learn more about them and what they do. This is something I personally enjoy, but a lot of the public aren’t aware of these animals.”

The booklet features a primer on mussels and a glossary of important terms along with vivid photographs and information about each of the 63 species of mussels found in the state, including maps of their ranges.

Hopper became interested in freshwater mussels while in graduate school at Kansas State University. After completing his doctorate, Hopper researched the bivalve creatures for four years in Alabama, a state with an incredibly diverse mussel population. The intriguing creatures’ lives captivated him.

“There’s this complex life history where mussels need a fish to carry around their parasitic larvae,” Hopper said. “That can be a very specific interaction between one mussel and one fish or many different kinds of fish and one kind of mussel.”

Mussels grow from larvae and form dense beds, living for decades while they feed and filter water and store bacteria and other substances in their tissues as they grow. The waste they produce becomes available to algae and aquatic plants, Hopper said, and “fuels the bottom of the food web.”

Nutrients from mussel beds can be traced to plants along the stream banks and into insects that emerge from the stream and provide food for birds, bats, spiders and other animals.

“Those mussel beds form these really big hot spots of biodiversity,” Hopper said.

Hopper strives to better understand these organisms and what purpose they serve in the ecosystem. Through the work of Hopper’s lab, graduate students are studying mussels’ nutrient cycling in the Bogue Chitto River and have surveyed mussels in Bayou Pierre in the northwestern region of the state.

“We all need freshwater,” Hopper said. “Ultimately, protecting mussels and fish and learning more about them and how they interact with their environment is really important for understanding how to keep our freshwater safe and healthy.”

The lab recently received funding from the Environmental Protection Agency for a long-term study of mussels in six of Louisiana’s rivers: the Sabine, Calcasieu, Atchafalaya, Tangipahoa, Tchefuncte and Pearl.

“We’re going to learn a lot about the life history of different mussels, and then we’re going to compare what we collect now to mussels in museum collections that are from relatively similar locations that predate the Clean Water Act.”

“It can help address whether or not freshwater systems are healthy here in Louisiana,” Hopper said. “We’ll be looking for mercury in the soft tissue. I know a lot of people are interested in that. Because these animals sit in the mud at the bottom of the river for decades and decades, they just collect things. We can use them to collect information about the river.”

Learn more about mussels and the work of Hopper’s lab at https://garretthopper.wixsite.com/streamecology/outreach.

Franchesca Ruiz, a senior in the LSU School of Renewable Natural Resources, became fascinated by mussels early in her college career. She has contributed to a comprehensive guide to the freshwater mussels of Louisiana that was published this month. Photo provided by Franchesca Ruiz

Franchesca Ruiz and Garrett Hopper worked to create Freshwater Mussels of Louisiana: A Field Guide to help educate people about freshwater mussels in the state and spread the word about the importance of these animals as wildlife and a natural resource. LSU AgCenter file photo

Garrett Hopper, an assistant professor of aquatic ecology at the LSU AgCenter, studies the freshwater fish and mussels of Louisiana and aims to educate the public about their important place in the ecosystem. Photo provided by Garrett Hopper