When a group of laborers began digging a well in San Marcos, Texas, in 1895, they had no idea they would soon encounter what naturalist Leonhard Stejneger described as “one of the most important and interesting herpetological events of recent years.” After about 60 meters of drilling, the workers were awarded with a gush of fresh water, still cold from its tenure in the deep, underground caves of the Edwards Aquifer. Their excitement quickly dimmed to confusion as a barrage of translucent salamanders surfed upward on the projectile stream of groundwater. 

Even though people had lived in the area more than 13,000 years, there were no records of an animal matching the salamander’s alien appearance. “The legs are very long and slim; the animal lacks pigment; the eyes are aborted,” reads one description, written years after the creature’s initial discovery. Scientists catalogued these bizarre features and puzzled over what, exactly, they were studying. Finally, in 1965, the Texas blind salamander received the taxonomic classification of Eurycea rathbuni.

Even today, mysteries surround the amphibian. But geneticist Katie Bockrath is trying to change that at the San Marcos Aquatic Resources Center (SMARC) where she leads the Edwards Aquifer Species Conservation program. The program houses the world’s largest captive population of Texas blind salamanders alongside many of the other salamanders, fish, and aquatic invertebrates native to the Edwards Aquifer.

“First and foremost, there is intrinsic value,” Bockrath said of the animals she works with. “These species are only found here, and if they go away, they’re gone.”

Randy Gibson, a supervisory biologist at the San Marcos Aquatic Resources Center, sets up nets near a natural spring. | Photo by Pete Diaz/USFWS

The Edwards Aquifer encompasses as much as 8,000 square miles in central Texas, but most of the species associated with the aquifer dwell in a few select pools and springs. This exclusivity puts many species at risk, especially as more wells are drilled to supply the growing population of central Texas with fresh water and climate change intensifies existing drought cycles. The fees that municipalities and large industrial companies pay to withdraw water from the aquifer fund the refugia. Scientists believe that at least one species, the San Marcos gambusia, has already gone extinct, and seven others, including the Texas blind salamander, are currently listed as endangered species by both the state and the federal government because of concerns for the quantity and quality of water in the Edwards Aquifer.

In 2017, as part of the Edwards Aquifer Habitat Conservation Plan, the Edwards Aquifer Authority requested SMARC establish an “off-site refugia” for 10 animal species and one plant species. The plan stressed that the Edwards Aquifer Authority would continue to conserve the wild habitat of these creatures while also caring for a captive population to serve as a “safety net,” ensuring that an unexpected event would not cause total extinction, and extending a unique opportunity to study otherwise inaccessible animals. Cave-dwelling species such as the Texas blind salamander are difficult to observe in the wild, but scientists have been able to gain firsthand insights into the lives of these elusive creatures through SMARC’s captive population. 

“We start[ed] off with nothing,” said Bockrath. “We knew nothing about these guys.”

To capture their first specimens, SMARC researchers outfitted the mouth of wells and springs with nets. When heavy rainfall inundated the aquifer, the excess water flushed underground critters into the nets. Bockrath also found that baiting the traps with pistachios made them extra enticing.

For every four salamanders captured, one joins the refugia. The other three are released after a short surgical procedure in which researchers take a clipping from each salamander’s tail, for DNA analysis, and insert a half-square-millimeter microchip under its skin. The microchip tags the individual with a unique identifier, allowing scientists to track the salamander as it moves through the aquifer. 

Back at the lab, captive salamanders are quarantined for 30 days before being released into temperature-controlled tanks. A stream of water pumped from the section of the Edwards Aquifer just below the SMARC facility circulates through the tanks, to emulate natural habitat conditions as closely as possible.

Researchers quickly discovered that each species had a distinctive personality. The San Marcos salamanders (Eurycea nana) liked to slither under rocks and plastic plants in their terrarium, making them nearly impossible to spot, but the Comal Springs salamanders (Eurycea pterophila) were far more adventurous, often escaping their tank. The Texas blind salamanders proved to be gluttons, and Bockrath joked that they had become “chunks” on a specially curated diet of worms, daphnia, and lipid-infused sea monkeys.

In addition to helping animals, the San Marcos Aquatic Resource Center is conserving native plants, such as Texas wild rice, in this propagation area. | Photo by Hailey Smalley

This diet is just one example of the knowledge gained over seven years of research and observations. While collecting, caring for, and breeding salamanders, SMARC scientists have published studies on everything from the hormones that trigger reproduction to the movement of wild salamanders through the aquifer.

“We’ve had the opportunity to learn so much more about these species,” Bockrath said. She considers this increasing knowledge base to be the program’s largest success, but there are still more questions to answer.

One of the biggest unknowns is the true extent of the Edwards Aquifer’s biodiversity. SMARC has successfully established a refugia for Comal Springs riffle beetles, Comal Springs dryopid beetles, Peck’s Cave amphipods, fountain darters, and Texas wild rice, but others have yet to receive the same rigorous attention. As of 2019, scientists had identified over 60 species endemic to the Edwards Aquifer. Randy Gibson, a supervisory biologist at SMARC specializing in invertebrates, believes this is just the tip of the iceberg.

“We’re still discovering new species,” said Gibson. “Most of the diversity is in little tiny things that nobody is looking at.”

Gibson is hopeful that SMARC’s ongoing research will draw attention to the role small species, such as aquatic beetles and amphipods, play in environmental health. He said that many of the invertebrates SMARC studies could be used to better understand and manage the Edwards Aquifer. Population declines could prove an essential warning to poor water quality, and the movements and evolutionary histories of different species could help map out otherwise inaccessible parts of the aquifer.

“It’s not just about a beetle,” Gibson concluded. It’s about the rivers, the springs, the underground caves. It’s about an entire system of water and the plants, animals, and people that rely on it.