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NSF PR 95-73 - October 24, 1995
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Cheryl Dybas |
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Program contact: |
Cliff Dahm |
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Feature Buried in Romania: Forever-Dark Cave Crawling
With Life
It's a scene straight out of a Halloween horror flick:
Isolated from the world for millions of years, forever-dark
Movile Cave in Dobrogea, Romania is crawling with
life. Despite the fact that the cave receives no energy
from the sun, a unique community of animals stalks
its tortuous inner reaches: hundreds of spiders and
other creatures, and previously unknown microbes.
Water scorpions, predatory leeches, and troglobites,
oh, my!
Funded by the National Science Foundation, a team
of biologists from the University of Cincinnati will
soon return to the cave to conduct further research.
An artificial entrance shaft, created by accident
during a construction project, first allowed scientists
access to the subterranean system. Biologists found
a diverse, and by cave standards abundant, fauna in
the dank chambers -- some 47 animal species to date.
Thirty of the 47 species were previously unknown.
In a pattern called troglomorphy, all show a reduction
or loss of eyes and pigmentation, and enlargement
of appendages and what scientists call extraoptic
sensory structures, "antennae" of gigantic proportions.
The ancestors of some of these species may have become
isolated from their surface-dwelling relatives more
than five million years ago, when the climate of southern
Romania became very dry. Today, these creatures are
an underground Addams Family.
Located west of the Black Sea and bordered by the
Danube River and the Casimcea Valley, Movile Cave
was discovered in 1986. It was not explored, however,
until the fall of Romanian dictator Nicolae Ceausescu.
Since then, researchers have proved that there are
no links between the outside world and the cave's
hidden galleries and air bells, or pockets. Cave sediments
are also devoid of Cesium radionuclides, significant
because surface sediments in Dobrogea contain high
levels of these nuclides, due to the 1986 Chernobyl
accident.
"So food and bacteria don't come in from the surface,"
says University of Cincinnati biologist Brian Kinkle.
"The sole sources of food appear to be hydrogen sulfide
and methane from groundwater trickling through the
cave's inner chambers."
Thick deposits of loess -- silt mixed with fine sand
or clay -- overlying the cave's limestone surface,
and a lack of nutrient-rich surface streams or lakes
in the region, indicate that the cave's animal community
receives little, if any, organic input from the surface,
according to biologist Thomas Kane, also of the University
of Cincinnati. "Despite the extreme isolation of the
system, which has apparently existed for some time,
the huge population sizes of the invertebrate species
in the cave suggest a large energy base. And the presence
of thick microbial mats in the cave's deeper recesses
supports this idea."
Movile Cave differs in two important aspects from
other caves: Its waters are much warmer than those
of "typical" limestone caves, and are rich in hydrogen
sulfide. To find out which strains of bacteria are
most important in converting this hydrogen sulfide
to a food source, the scientists are studying unusual
microbes growing in waterborne mats on the cave's
walls, and in its underground lake. Says Luminita
Sarbu, a graduate student at the University of Cincinnati,
"We developed fluorescent antibodies that bind only
with certain strains of bacteria, and used them in
the cave samples to see how abundant these bacteria
were. We're now checking to see how important a component
the bacteria are to life in the cave." The scientists
must take extreme care not to contaminate the cave's
fragile environment. Only three people are allowed
in the cave at a time, for periods of one hour. Researchers
change their clothes upon entering the cave, to avoid
bringing in "foreign" microbes. By returning to Movile
Cave, Luminita Sarbu hopes to determine whether stringy
filaments she's seen under the microscope are fungi.
"Some filamentous bacteria can be as big as fungi,
so judging by size alone is not enough." If the suspected
fungi turn out to be the real thing, yet more questions
will arise. How can the fungi survive when so little
organic material exists in the cave? Do they have
unique metabolisms, or have they adapted in some way
to the scarcity of food?
The answers lie hidden in Movile Cave's black depths,
the perfect setting for a Stephen King novel.
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