Slipping under Texas Biologists search for unique species

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Slipping under Texas Biologists search for unique species

Postby Lynn » Jan 26, 2006 9:05 am

Slipping under Texas
Biologists search for unique species

By Scott Solomon

Floating on a crystalline stream just beneath the reach of jagged stalactites, Andrew Gluesenkamp is surrounded by complete darkness except for the sweeping beam of his headlamp underwater as he slowly moves deeper into the cave. His tattered, multicolored wetsuit is the only speck of color in an otherwise dark and gloomy world.

Suddenly, he lets out a muffled scream through his snorkel. He has found what he is looking for. A small, pale creature, no larger than a guppy, swims toward the muddy cave floor, its thin, delicate limbs tucked close to its body as it wriggles from side to side in an attempt to escape.

Gluesenkamp emerges from the water, a big grin clearly visible through his dive mask. He holds the creature in a net and examines it in the beam of his headlamp. It has a flat head, almost no eyes and a pink mane, which is actually its gills.

They look like deep-sea creatures," Gluesenkamp says, referring to the animals' complete lack of pigment and vision.

Gluesenkamp, a freelance biologist, has captured a Cascade Cavern Salamander from deep inside Honey Creek Cave in Comal County. It is one of several species of blind salamanders thought to be unique to Central Texas. The Edwards Aquifer, which spans 175 miles from Salado to Del Rio, is a hotspot for cave life, with dozens of species of fish, amphibians, insects and other invertebrates living right beneath the surface. Thousands of caves exist in the area, many of which are connected directly to the aquifer. Gluesenkamp's research aims to uncover some of the basic facts about these salamanders, such as how many species there are and where each one lives.

Such information is critical to help conservationists decide which species need to be protected, as the life in these caves is threatened by the increasing human population in the region. Gluesenkamp, along with other biologists and cavers, is racing to learn about these unique species before they disappear.

"Hidden diversity beneath our feet"

The blind salamander is a living example of how evolution can shape an organism to fit its environment. Known to scientists as Eurycea latitans, it has lost both the pigment in its skin and the function of its eyes, which have been reduced to tiny dots. It keeps its frilly, pink gills throughout its lifetime, unlike other salamanders, which lose them when they leave the water to live on land. This cave-adapted species never leaves the water, so it has evolved to retain its gills.

Gluesenkamp's enthusiasm for these animals is contagious. He refers to the incredible variation among cave organisms as "hidden diversity beneath our feet." In addition to salamanders, the dark recesses of caves such as Honey Creek are home to many cave-adapted invertebrates. As seen through a clear plastic box used to reduce glare from the water's surface, cave isopods, which are related to pill bugs or "roly-polies," look like small, pale aquatic centipedes, with long legs extending out from the front and the back of their flat bodies. Above the water, slender, elegant-looking ground beetles crawl about, searching blindly for cave cricket eggs. The crickets leave the caves at night to find food and serve as an important intermediary between the two worlds, bringing organic material and energy into the cave, which species inside depend upon for survival.

Biologist Jean Krejca, a friend and colleague of Gluesenkamp, led a team that recently discovered 27 new species of cave-adapted animals in three national parks in California. Among them was a spider with jaws more than half the size of its body. Krejca, who also received her doctorate from UT, speculates that it uses these massive jaws to crush snail shells, which they are thought to feed upon. The team also discovered a new species of flatworm that they were able to find in only one pool of one room within one cave, suggesting that it is incredibly restricted in range and therefore exceedingly rare according to Krejca, whose environmental consulting firm, Zara Environmental LLC, is based in Buda.

Gluesenkamp remains confident that even more species exist in California's caves, but a lack of taxonomists, biologists that specialize on identifying and describing new species, made their report an underestimate of the total diversity.

"The number easily could have been 54, and not 27," Gluesenkamp says. "If only we could have found more taxonomists."

"A window into the aquifer"

Despite the high number of species Krejca and her colleagues found in California, Krejca believes Central Texas still has a greater diversity of cave-adapted creatures because of its proximity to highly diverse tropical regions of Central America. She says that many of the ancestors of Texas cave species came from that region, although Gluesenkamp believes the ancestors of the blind salamanders came from the eastern United States. Both biologists say that being between these two areas contributes to the high diversity of Texas cave fauna.

A few Texas caves stand out as showcases for biodiversity. Ezell's Cave, in Hays County, for example, provides what Gluesenkamp calls "a window into the aquifer," allowing researchers direct access the underground waterway and its inhabitants.

"Ezell's Cave is probably the most famous cave in terms of biology in the world," Gluesenkamp says. "Most of the invertebrates known from the aquifer were described from that cave."

He says that the diverse fauna of Ezell's Cave was nearly destroyed when a cover was installed on the cave entrance to prevent access by untrained cavers. The cover prevented not only people, but also the bats that roost inside the cave from entering. The entire cave ecosystem depended on the bats bringing nutrients and energy into the cave during their nightly excursions. When the bats disappeared, so did the other cave life.

Joe Furman, a driver for UPS and part-time documentary filmmaker, is working on a movie about Ezell's Cave and the complex yet fragile interactions between its former inhabitants. In order to recreate the cave community, Furman is following Gluesenkamp in search of the various species that used to live in Ezell's Cave, which he hopes to film.

"I'm going to put it together like it has been for thousands of years," Furman says, "put it together like it was."

A river runs through it

Thousands of caves have been discovered and explored in the limestone hills of central Texas. Philip Rykwalder, a geologist and cave enthusiast who joined up with Gluesenkamp to search for salamanders, says that these caves formed as a result of millions of years of water moving through the rock.

"Limestone is comprised mainly of calcite," Rykwalder says. "While the water moves, it dissolves away the calcite."

This leaves empty cavities, which allow even more water to pass through, enlarging the passage.

"If you have large cavities and conduits," he says, "more caves are likely to form."

In caves such as Honey Creek, this process is still occurring. The slow-moving stream that flows through Honey Creek Cave has carved a passage that is about 15-feet wide near the entrance, but upstream, it splits into several channels.

"Picture a tree and all its branches," Gluesenkamp says, describing the layout of the various chambers radiating from the main passage.

According to Gluesenkamp, spelunkers in the mid-1960s had a hole drilled into the ground about two-and-a-half miles from the natural entrance to facilitate exploration of the cave's deepest recesses. They attached themselves to a rope that was linked through an elaborate system to the back of a tractor. The tractor would first move forward, raising the person over the shaft, then slowly back up, lowering them 140 feet down into the abyss. By the time the entire cave system was explored, it was found to be the longest in Texas, at nearly 20 total miles of underground rivers.

Rykwalder, who manufactures expedition-style caving bags to help pay the bills, wonders how many other caves in Central Texas await discovery.

"We don't see most of the caves, because they're all under water right now - they're a thousand feet down," Rykwalder says.

He says there are also many small caves that probably contain life, but are too small to be explored by people.

"Caves are voids that humans can fit in," Rykwalder says. "But of course there are lots and lots and lots of voids, far more voids, that humans cannot fit in."

"The muddy office"

For Gluesenkamp, Honey Creek Cave is about more than just rare salamanders. It was the site of his first caving experience. When Krejca took him there in 1998, he was instantly hooked.

"I have Jean to thank for baptizing me," he says. "I went caving eight of the next nine weekends after that."

Prior to learning about caving and blind salamanders, Gluesenkamp studied the evolution of frogs as a graduate student at UT. He received his doctoral degree in zoology in 2000, then completed post-doctoral laboratory research in Los Angeles, which he did not particularly enjoy.

"I had a post-doc salary in LA, and I was buying groceries with jars of change," he says.

He did not care much for lab work and was eager to get back to the field. After he finished his post-doctoral studies, he returned to Texas where he worked to enlarge cave entrances in order for researchers to access rare species.

"It's something else swinging a pick for a living after you get your Ph.D.," Gluesenkamp says. But the work satisfied his need to be close to the organisms he loves, and he felt his work was making a difference.

"The caves aren't all that big," he says. "But they're chock full of endemic species - a lot of listed, endangered species." Now a freelance biologist, Gluesenkamp is able to work in what he calls his "muddy office," pursuing his interest in cave salamander research in the field as much as possible. His skills as a caver make him one of only a handful of scientists able to find Eurycea cave salamanders in the field and study them in their natural environment. As a result, Gluesenkamp is able to secure funding from non-governmental organizations as well as state and local government agencies.

The risks of working in caves include hypothermia from prolonged exposure to cold water and suffocation as a result of the high levels of carbon dioxide that are often present in caves and can be lethal. These risks can be avoided with careful preparation and training, according to Colin Peden, president of the UT Grotto, a chapter of the National Speleological Society, a club for cave enthusiasts.

"Good cavers go into caves very well prepared," Peden says.

In addition to gear such as helmets, ropes and at least three sources of light, Peden says it is important not to forget water and extra batteries.

The difficulties biologists face in accessing cave-adapted species, as well as a general lack of knowledge about their biology, make it difficult to assess their risk of extinction, according to Gluesenkamp. He believes that learning more about their natural history, including important data such as how many individual salamanders remain in certain caves and springs today, will help to protect these unique animals. Such basic biology, according to Gluesenkamp, "is the sharpest sword in the cabinet for making conservation arguments."

In the coming months, Gluesenkamp plans to begin searching for the rarest of all cave salamanders - the Blanco blind salamander, Eurycea robusta. Five of these large, white salamanders were discovered in the summer of 1951 in the Blanco River, when local residents tapped into a small underground water source that quickly dried up.

According to Gluesenkamp, the locals collected two specimens, which he described as "muscle-bound" in comparison with the scrawny-looking species in Honey Creek. One of these was eventually lost. The other still sits, preserved, in the herpetological collection at UT and remains the only example of this species known to science. Although no one has ever seen the species again in the wild, Gluesenkamp is determined to find it and learn about its ecology, before rapid development in the area ensures the loss of its natural habitat and therefore its extinction. For him, it would be the discovery of a lifetime.

"Finding robusta," he said, laughing, "would be like finding a panda in Alaska."

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