Texas Hill Country Cave Dwellers: Freshwater Species of the Week

Comal Springs Riffle beetle. Joe N. Fries, USFWS


My parents recently retired to the Texas Hill Country, a picturesque area outside Austin and San Antonio that is home to a unique, dry ecosystem, as well as working ranches. There are also caves in those hills, some of which are home to endangered species (and possibly cattle rustlers).

This week, the U.S. Fish and Wildlife Service proposed to set aside 169 acres of “critical habitat” for three invertebrates in the region, in Comal and Hays counties, Texas. This includes two insects and a crustacean, namely the Comal Springs riffle beetleComal Springs dryopid beetle, and Peck’s cave amphipod.

These three freshwater species are known to exist only in four springs in the Hill Country, although scientists have warned that they have been at risk due to pumping of the Edwards Aquifer.

“These unique Texas creatures need protection of both their surface water and the underground recharge area, and I’m so pleased they’re getting the protected critical habitat they need to survive,” Tierra Curry, a conservation biologist at the Center for Biological Diversity, said in a statement.freshwater species of the week

The Center (along with Citizen’s Alliance for Smart Expansion and Aquifer Guardians in Urban Areas) had sued the Fish and Wildlife Service to force them to designate critical habitat, after those species were listed under the Endangered Species Act in 1997. Critical habitat was protected in 2007, “but that designation was deemed insufficient by scientists because it included only surface water and not the underground recharge area crucial to the species’ survival,” reports the Center. “The Center and allies again filed suit, resulting in today’s proposal.”

Picture of Peck's Cave amphipod
Peck's cave amphipod. Joe N. Fries, USFWS

The new areas overlap and include: 39 acres of surface habitat and 139 acres of subsurface habitat for the Comal Springs dryopid beetle; 38 surface acres and 138 subsurface acres for the Peck’s cave amphipod; and 54 acres of protected surface habitat for the Comal Springs riffle beetle.

The Peck’s cave amphipod depends on clean water and steady flows, although it has shown some resilience at surviving through droughts in the past. Still, as the aquifer has been pumped down, flows have decreased, driving its numbers down.

The Comal Springs riffle beetle is an aquatic insect that has a mass of tiny, unwettable hairs on its underside. It uses these hairs to form a bubble of air so it can breathe underwater. But it needs clean, strong flows with relatively high levels of dissolved oxygen for this innovative technique to work.

The Comal Springs dryopid beetle is a blind aquatic insect that can’t swim. It lives in air-filled cavities underground.

Comal Springs dryopid beetle
Comal Springs dryopid beetle. Photo: Photo by Joe N. Fries, USFWS

Brian Clark Howard covers the environment for National Geographic. He previously served as an editor for TheDailyGreen.com and E/The Environmental Magazine, and has written for Popular Science, TheAtlantic.com, FastCompany.com, PopularMechanics.com, Yahoo!, MSN, and elsewhere. He is the co-author of six books, including Geothermal HVACGreen LightingBuild Your Own Small Wind Power System, and Rock Your Ugly Christmas Sweater.