Known as the "liver of the river," mussels are considered one of nature’s greatest filtration systems, according to biologists. They purify water by feeding on algae, plankton, dead wildlife and sediment.
But these unique creatures, which look and feel like rocks, are more special than we think, filtering almost 15 gallons of water daily.
Last week, the U.S. Fish and Wildlife Service listed six Central Texas mussel species as endangered and another as threatened or soon to be endangered. These seven species are found in lakes and creeks throughout the region.
Biologists at the agency said the mussels were listed due to declines in water quality, loss of stream flow and habitat destruction. Urbanization and climate change exacerbate these threats.
The endangered mussels are not to be confused with zebra mussels, which have infested Austin’s waterways in the past few years. Zebra mussels are not native to North America and disrupt entire ecosystems by consuming large amounts of aquatic food needed by other wildlife.
Ryan Blankenship, a certified wildlife biologist with Environmental Consulting and Technology, says North America is known as the “mecca” for freshwater mussels: There are more species here than anywhere else in the world. However, they’re easily overlooked.
"Freshwater mussels are not cute and they're not cuddly and they're not charismatic, but they do serve a very important ecological role in our river systems," Blankenship said. "I've done enough public outreach to know that most people don't even know that these animals are in our rivers."
The U.S. Fish and Wildlife Service identified 1,577 river miles essential to the mussels' conservation, including the Brazos, Colorado, Guadalupe and Trinity river basins. After the endangered listing goes into effect July 5, any work occurring in these areas will require consultation with federal agencies.
Blankenship said he expected the mussel species to be listed as endangered after the agency published the Texas Freshwater Mussel Survey Protocol with the Texas Parks and Wildlife Department in 2021.
“We sat in limbo until ... the press release from the U.S. Fish and Wildlife Service came out," he said. "This has been a long time coming.”
Blankenship said river authorities in the region were educated ahead of the listing. They’ve created voluntary agreements to protect the waterways.
“They knew this was coming. Now there’s going to be a regulatory hook to ... adhere to the Endangered Species Act," he said. "It won’t just be a voluntary good-faith effort.”
More than anything, native freshwater mussels are biological indicators of healthy streams and rivers, which benefit people and wildlife. If we don’t have mussels, we don’t have good water.
“They're kind of our canaries in a coal mine,” Blankenship said. “The fact that these mussel species are not doing well and that we’ve seen these massive declines is maybe an indicator of a larger biological health and biodiversity loss and water quality degradation.”
