A Strange, Endangered Ecosystem Hides in Underground Waterways

This story originally appeared on Undark and is part of the Climate Desk collaboration.“I DON’T KNOW that there’s much to prepare you for entering a black hole,” said Ruben Tovar. In the fall of 2021, Tovar was outside of San Antonio, Texas, preparing to enter a hole in the ground the size of an oven door—the entrance to a cave carved out of the limestone.Equipped with climbing gear and flashlights, Tovar and his caving partner descended into gloom, shimmying down a roughly three-story near-vertical tunnel and brushing up against colonies of spindly-legged cave crickets. Along the way, Tovar could see water seeping through the limestone walls. There had been storms the week before and the rain was slowly percolating into the Edwards Aquifer, a vast reservoir of fresh water below.Tovar was looking for salamanders. While many people might more readily picture a salamander hiding under a log, the Texan underground is home to a subterranean aquatic ecosystem rich in these lizard-like amphibians, as well as invertebrates and fish, hidden where humans can barely visit.

Groundwater—held in caves, pores, and cracks—is actually the world’s largest unfrozen freshwater habitat, containing more water than all lakes and rivers combined. And where there is water, there is life. Often blind, pale, and adapted to live in near starvation, these groundwater-dwelling animals—known as stygofauna—are poorly understood and difficult to study.

But lately scientists from France to India and Australia are using genetic and chemical techniques to better understand stygofauna—and warning that many of these strange creatures may soon face extinction, including Texas’ salamanders. Many people rely on groundwater for drinking and domestic use, and in the past it has often been treated like an infinite resource. But groundwater is already running out in many areas. And the world is going to get even thirstier in the coming century: According to the World Meteorological Organization, by 2050, 5 billion people may lack adequate access to water.

How much are humans willing to do—or give up—to save an ecosystem that’s largely impossible to visit or even see? And if this ecosystem is damaged, what is at stake?

Conserving salamanders and other underground life is a “huge deal,” said Tovar, “because they rely on the water that we rely on.” The health of underwater ecosystems can act as a barometer for the health of everything living aboveground, too, including people. And when it comes to understanding underwater ecosystems, Tovar added, “we’ve only scratched the surface.”

RESEARCHERS HAVE KNOWN about Texas’ underground salamanders for more than a century, ever since a dozen or so turned up in a newly drilled well in San Marcos in 1895. But finding more has often been pure accident. Workers digging up a spring near a dry riverbed in 1951, for instance, discovered four specimens of a species now known as the Blanco blind salamander, but left unattended, the story goes, two were quickly eaten by a heron. Another was lost, leaving science with only a single specimen of the species to this day.