Ghost Fish of the Ozarks
Mystery and imagination take over when we think about caves. These dark places harbor magical creatures. In fact, stories of "ghost fish" living in caves have been told since the days Native Americans roamed the Missouri Ozarks.
That "ghost fish" today is known as the Ozark cavefish. It is a 2-inch long, pale, almost colorless blind fish living only in caves and springs on the Springfield Plateau of southwest Missouri and nearby parts of Oklahoma and Arkansas.
Ruth Hoppin, a caver and explorer, collected cavefish in Jasper County in 1888. She also collected the first specimens of the bristly cave crayfish, an unpigmented, blind crayfish that has a range similar to the Ozark cavefish.
Like many other cave-adapted animals, Ozark cavefish have lost their skin pigmentation, leaving them so translucent that their blood vessels are visible. Eyes are unnecessary for creatures living in near perpetual darkness, so they have gradually devolved to become small spots of residual nerves. Although cavefish do not have eyes, they "see" with sensory organs on their head and sides. These small whiskerlike projections help the fish feel its way through the water and detect the movements of prey.
Because the nutrient supply is limited in a cave, Ozark cavefish are not picky about what they eat. Cavefish eat bacteria, fungi, protozoans and aquatic insect larvae, as well as mites that feed on decaying organisms brought into the cave by animals. Their diet also includes plankton (microscopic plants and animals) and small invertebrates, such as crayfish, cave crickets, salamander larvae, amphipods and isopods. If food is really hard to find, they may even eat their own young.
Because caves have relatively constant temperatures and stable dissolved oxygen levels, cavefish have evolved low metabolic rates and do not require much food. Regardless, life in a cave is life "on the edge."
When the early settlers dipped drinking water out of the well, they sometimes found cavefish in their bucket. The custom of calling them "spring keepers" or "well keepers" sprang from these encounters. People saw them as a good luck charm and believed that the cavefish meant the water was safe to drink-a belief that continues today.
Clifford Lewis, a landowner near Sarcoxie in southwest Missouri, remembers seeing cavefish when he was a boy. "My brother and I were mowing hay on a hot summer day. When we got thirsty, we headed to the nearby cave to quench our thirst with spring water. Those blind fish were all around. It was not unusual back then to see 10 to 15 cavefish."
Ozark cavefish have declined over the years and now are federally threatened. There were probably never great numbers of cavefish, and scientists and curiosity seekers who collected specimens may well have contributed to their decline. It is now illegal to collect the Ozark cavefish.
The most important factor causing the decline of the cavefish has been pollution in the groundwater caves where they live. Polluted surface water enters the underground water supply through sinkholes, losing streams and percolation through the thin soils and cracked limestones and dolomites of the Ozarks.
Too often these surface waters carry human sewage, agricultural wastes and heavy silt loads from a variety of sources. Once underground, the polluted water destroys the delicate balance of life found there. The "ghost fish" is one of the first to disappear.
Landowners can help reduce threats to Missouri's cave systems and the organisms that live there by following a few simple guidelines:
- Make sure your septic tank and tile fields are installed properly and maintained.
- Dispose of all trash and other solid wastes properly.
- Control domestic animal waste runoff and repair leaking sewage lagoons.
- Keep forested buffer areas near cave entrances and sinkholes and along streams. These provide a natural filter that improves water quality. Buffer zones also trap soil particles and ensure that cleaner water enters the underground system.
- Put up fences or gates around sinkholes or cave openings on your property that allow wildlife to enter but restrict human access.
- Seal abandoned wells properly.
Missourians have a tradition of concern for all of our wildlife resources, including those that do not appear to have food or sport value, like the Ozark cavefish. We cherish the song of the green tree frog and the sizzle of a crappie fillet in the pan with equal ardor.
A number of concerned Missourians have joined forces to improve the habitat of the "ghost fish." The Conservation Department has worked in several southwest Missouri counties to reestablish wooded corridors along streams, cap open wells, fence cave entrances and sinkholes and post educational signs. Biologists also remove introduced fish species that prey on cavefish and compete with them for food.
One individual can make a significant difference. Charles Salveter, a southwest Missouri landowner, has fenced his cattle out of the streams and sinkholes that pass through a local cave's recharge area. He has also posted cave refuge signs to protect the cave's ecosystem. "There's so much nature being destroyed in the Ozarks," Salveter says. "We need to save what we can."
To learn more about cave conservation, write American Cave Conservation Association, P.O. Box 409, Horse Cave, KY 42749. Visit their web site at<http://www.cavern.org>
Technology Goes Underground
by Charlotte Overby
Ozark cavefish and other aquatic animals aren't the only imperiled creatures living in Missouri's caves. Missouri is or was home to three endangered species of bats-Indiana, gray and Ozark big-eared bats-and they need caves to survive. They use caves at various times of the year to hibernate, raise their young and seek shelter.
Thanks to the popular children's book, Stella Luna, the bat character in Disney's movie, "Fern Gully," and educational campaigns by conservation groups, bats are gaining popularity, says Bill Elliott, cave biologist for the Conservation Department.
"People are beginning to see bats as interesting, beautiful mammals that are beneficial because they eat insects," explains Elliott. "A single little brown bat, which inhabits many neighborhoods in Missouri, can eat up to 1,200 insects in just one hour."
Finding ways to save Missouri's bats is the responsibility of Elliott and bat ecologist Rick Clawson. They survey caves, gather data about bat populations and work to design steel gates over entrances to especially sensitive bat caves. They are trying to figure out why populations of some bats have plummeted. The population of Indiana bats, for example, has declined 80 percent in Missouri since 1983. Ozark big-eared bats are extirpated in Missouri; small populations live in Arkansas and Oklahoma.
The Conservation Department recently applied for a $1,477 grant to help purchase 12 palm-sized data loggers. They are digital devices that measure temperature and humidity. Installed inside caves, the data loggers track the microclimate on cave walls-near where bats hibernate and raise their young. Every six months, Clawson or Elliott returns to the caves and downloads data from the data logger directly into a laptop computer. They can instantly graph climatic conditions in the cave and begin to discover how climate affects the bats.
"Bats are very sensitive to disturbance. With data loggers, we get a great deal of data without disturbing the bats during hibernation' says Clawson. We used to get just one reading, on one day, in one spot in the cave. The data loggers give us continuous data, and we'll begin to see long-term trends and changes in their habitat."
In addition to using new technology for research, Clawson and Elliott are working to keep people out of sensitive caves and to educate Missourians about caves. Disturbance by humans is a big threat to the bats' survival. Bats possess limited stores of fat in their bodies, which they need to survive while hibernating. Every time they are awakened, they use up valuable energy. If they are disturbed too many times, they won't have enough reserves to survive until spring. During summer, when females nurse and raise young, people going into caves frighten the bats and cause the mothers to drop their young. The young bats die. Females only raise one offspring per year, so populations can be decimated by just one uninformed caver or vandal.
Bat Conservation International is working around the world-including Missouri-to support bat research, educational campaigns and preservation of habitat. The organization also publishes many beautiful books, photographs, calendars and posters about bats for people of all ages. Write Bat Conservation International, P.O. Box 162603, Austin, TX 78716; or call 512/327-9721. Visit their web site at <http://www.batcon.org>