Six Texas freshwater mussels, the “livers of the rivers,” added to endangered species list

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The U.S. Fish and Wildlife Service declared six species of freshwater mussels found in Central Texas as endangered and another as threatened on Monday.

Environmental scientists refer to freshwater mussels as “the liver of the river” because they filter harmful substances like algae from bodies of water. But the species, once found in abundance in Central Texas, have declined in recent years due to population growth and development destroying its habitat.

In its ruling, the agency also designated 1,577 miles of rivers and creeks in the Colorado, Guadalupe, Brazos and Trinity river basins as critical habitat or an area important to the species’ conservation and recovery. The designation bans development or projects that could harm the species and requires a federal permit or license, unless the permit seeker works with the Fish and Wildlife Service to modify their projects to protect the endangered species.

Texas is home to more than 50 species of native freshwater mussels. The new rule adds the Guadalupe fatmucket, Texas fatmucket, Guadalupe orb, Texas pimpleback, Balcones spike, and false spike to the endangered listing, meaning the species is in danger of extinction. The Texas fawnsfoot is receiving a threatened listing, which means it is likely to become endangered in the future.

Experts say this designation will result in cleaner rivers, streams and creeks.

“[Freshwater mussels] really are foundational keystone species in any river system,” said Shaun Donovan, a manager of environmental sciences at the San Antonio River Authority.

Donovan has worked for years on mussel conservation efforts in San Antonio. Most recently, he worked with other biologists and scientists to reintroduce mussels to the region’s river basin. He describes the freshwater mussels as living rocks.

Freshwater mussels eat algae and other bacteria, which helps clean water systems. According to the Wildlife Service, a single freshwater mussel can pump and filter between eight and 15 gallons of water per day, making them some of the most powerful filters in watersheds.

They also stabilize sediment at the bottom of a river, which keeps bugs at the bottom of the food chain healthy and numerous and increases biodiversity. The creatures come in all shapes, sizes and colors. They’re found if you dig through mud, sand or gravel at the bottom of a river. Some are textured, with ridges on the shells. Others are smooth and shiny.

But the creatures have been heavily impacted by changes to rainfall and droughts, which increase water temperatures when rivers are low. Their habitat has also been threatened by the construction of dams on rivers.

“The struggle is trying to figure out how to balance providing water for communities, while also making sure that there's water in those rivers to sustain wildlife,” said Charles Randklev, a research scientist and mussels expert at Texas A&M Natural Resources Institute.

Randklev said the new listing will promote water conservation because it provides protections for a species that depends on rivers.

“This is about awareness. I think of mussels, but really what I do is I think of these rivers, and I do think we have a job to make sure that those rivers are around for future generations,” he said.

The Fish and Wildlife Service said that several water authorities in Texas including the Brazos River Authority, Lower Colorado River Authority, Trinity River Authority, and Tarrant Regional Water District have entered into voluntary conservation agreements. These agreements outline actions river authorities can take to reduce threats to the species, like making sure there is enough water flowing in rivers and addressing water quality for mussels to thrive.

“Creative collaboration with Central Texas river authorities has led to some groundbreaking conservation actions making it possible to list the Texas fawnsfoot as threatened,” Amy Lueders, the agency’s southwest regional director, said in a press release.

“That's important because it opens the door to more flexibility for solutions that reduce the threats to these mussels while boosting water quality in the watershed,” Lueders added.

Disclosure: The Lower Colorado River Authority and the San Antonio River Authority have been financial supporters of The Texas Tribune, a nonprofit, nonpartisan news organization that is funded in part by donations from members, foundations and corporate sponsors. Financial supporters play no role in the Tribune's journalism. Find a complete list of them here.

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