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Faculty Research Spotlight

Benjamin Schwartz, Department of Biology and Edwards Aquifer Research and Data Center Director

Edwards Aquifer Close to Being World’s Most Biodiverse Site


“We have discovered that nearly twice as many species occur in the artesian well on campus than previously described, making it very close to being the most biodiverse single site in the world.”

Dr. Schwartz in Bob Marshall Wilderness, Montana: Hauling gear during a wilderness expedition to help map what is now the deepest cave in the USA
Dr. Schwartz in Bob Marshall Wilderness, Montana: Hauling gear during
a wilderness expedition to help map what is now the deepest cave
in the USA

The earliest discoveries of strange eyeless and albino animals living in the Edwards Aquifer were made soon after the first artesian well was drilled in 1895 (now known as the San Marcos Artesian Well: SMAW). This well was drilled on what is now part of the Texas State campus. After the transfer of ownership, easy access to the site led scientists to begin a more focused study spanning from the 1960s through the early 1980s. In 1981, the Edwards Aquifer was hypothesized to be the most biodiverse aquifer in the world, but soon after that, discoveries and research slowed. Other aquifer systems in Europe and Australia received persistent attention and were documented as the most biodiverse aquifers.

During the late 2000s, we began work to learn more about the number of species and the organization of animal communities in the Edwards Aquifer. We assumed that pretty much all the species had been discovered and scientifically described, especially here at the SMAW. Incredibly, over the last 10 years, our work has revealed that this could not be farther from the truth. We have discovered that nearly twice as many species occur in the artesian well on campus than previously described, making it very close to being the most biodiverse single site in the world. Many undescribed species remain to be described both here at SMAW and throughout the karst aquifers of Texas. With more work, the Edwards Aquifer could certainly regain the crown of “most biodiverse aquifer.” This has opened a new phase of research on the aquifer, and we are beginning to understand how little we actually know about how this deep and isolated ecosystem works.

Our current research is focused on several long-term goals: 1) fill some of the very large gaps in knowledge about diversity in deep aquifer ecosystems (amazingly, we know more about deep-sea creatures than we do about creatures in the aquifers beneath our feet), 2) understand how biodiversity and deep aquifers evolve, and 3) understand the function of life forms that inhabit the deep Edwards Aquifer from microbes to vertebrates.

Gaps in our knowledge can be filled by curating existing historical information and samples, searching for animals at new locations, and disseminating information to people and groups who can use it. To accomplish this, we are modernizing existing information and digitally curating existing and new collections so that the information is accessible and useable. Some of our funded research projects also focus on understanding habitat requirements and distributions of Texas species in need of state conservation. In the process we collect similar data for many other groundwater species. Finally, we publish research results, incorporate current knowledge in educational materials, and actively pursue and support collaborations with other researchers and resource managers who can use the information.

Dr. Schwartz in Lechuguilla Cave, New Mexico: Geologic sampling trip
Dr. Schwartz in Lechuguilla Cave, New Mexico: Geologic sampling trip

A few examples may help illustrate our approach. From our previous research, we now know that species richness in the Edwards Aquifer depends on food produced by microbes in-situ in the absence of light, using chemical energy. In many ways, this is analogous to the strange ecosystems documented at deep-sea hydrothermal vents. However, whether this food resource is utilized by subterranean organisms near Barton Springs, including the federally endangered Austin Blind Salamander, is unknown. To answer that question, we are just now starting a project using stable isotope analysis to help define food-web structure in that sensitive habitat. Endangered groundwater-dependent species occur elsewhere in Texas as well. For example, no fewer than six federally endangered invertebrate species live in springs of the Trans-Pecos region. Although the arid Chihuahuan desert may seem an unlikely place for groundwater organisms, you can find isolated springs and other groundwater habitats scattered throughout that landscape if you know where to look. Those sensitive habitats are almost completely unassessed for groundwater organisms. Characterizing the groundwater communities of the Trans-Pecos (which we are funded to begin in early 2020) will fill a large knowledge gap for the state and help us better understand the conservation and management needs for one of the Trans-Pecos’ most sensitive resources: groundwater dependent ecosystems.

Aside from the thrill of finding and describing new life forms, our work has broad applications and implications. State and federal agencies tasked with managing resources need extensive information about how and where animals live in order to make informed management decisions. Especially in Texas, many species that depend on or live in aquifers are federally endangered or threatened. Resources invested in the maintenance, restoration, and regulation of habitat for these species are directly responsible for the continued flow at iconic springs such as the San Marcos and Comal Springs here in Central Texas. This is in contrast with many other springs around the state that have periodically or permanently ceased flowing due to poor groundwater management.

Current funding for this work is through US Fish and Wildlife Service, Texas Parks and Wildlife Department, and the City of Austin.