Devils Hole is a geologic formation located within the Ash Meadows National
Wildlife Refuge, in Nye County, Nevada Southwestern United States.
Devils Hole—a detached unit of Death Valley National Park—is habitat for the
only naturally occurring population of the endangered Devils Hole pupfish. The
40 acre unit is a part of the Ash Meadows complex, an area of desert
uplands and spring-fed oasis designated a national wildlife refuge in 1984.
Description Devils Hole is a geothermal pool within
a limestone cavern in the Amargosa Desert in the Amargosa Valley of Nevada,
east over the Amargosa Range and Funeral Mountains from Death Valley. Its waters
are a near constant salinity and temperature.
Devils Hole branches into deep caverns at least 300 feet deep from an opening
at the surface that is approximately 6 by 18 feet. According to geologists, the
caves were formed over 500,000 years ago. The pool has frequently experienced
activity due to far away earthquakes, which have been likened to extremely
small scale tsunamis. Devils Hole is the only natural habitat
of the Devils Hole pupfish, which thrives despite the hot, oxygen-poor
water. It is an IUCN Red List endangered species. The enclosing cave is
occasionally used as a roost for barn owls, which tend to increase diatom
growth via guano. Ash Meadows
Ash Meadows is the discharge point for a groundwater system extending over a
hundred miles to the northeast. Thirty seeps and springs bring to the surface
"fossil" water which entered the groundwater system thousands of years
ago. Ash Meadows is home to 26 species of endemic plants and animals, including
three other endangered fish and seven threatened plants.
Tsunami in the Desert Devils Hole is a window into this vast
aquifer and an unusual indicator of seismic activity around the world. Large
earthquakes as far away as Japan, Indonesia and Chile have caused the
water to 'slosh' in Devils Hole like water in a bathtub. Waves may splash as
high as two meters up the walls, sweeping clean the shallow shelf so
important to the pupfish. Devils Hole Pupfish
Earlier pluvial periods allowed colonization of present sites;
subsequent xeric conditions served to isolate the aquatic habitats, with the
result that the inhabiting organisms have differentiated and evolved into the
relict species found today. The Devils Hole pupfish have been isolated 10,000
to 20,000 years, longer than any other in the Death Valley system.
Devils Hole itself is a water-filled cavern cut into the side of a hill. The
cavern is over 500 feet deep and the bottom has never been mapped. Devils
Hole provides its resident pupfish with conditions of constant temperature and
salinity, unlike the fluctuating environments of many other pupfish.
Although pupfish have been found as deep as 66 feet, the fish forage and spawn
exclusively on a shallow rock shelf near the surface, feeding on the algae and
diatoms found there. The Devils Hole pupfish is considered an
annual species, with the historic population fluctuating between 100 - 200
in winter and 300-500 in late summer. Research indicates that pupfish
population numbers respond primarily to the amount of algae present on the
shelf. The algal growth depends, in turn, on the amount of solar radiation
the shelf receives and the concentration of nutrients in the water. Finally,
recent evidence suggests that nutrient availability is highest when the cave is
used by barn owls as a roosting/nesting site. The owls increase the pool
nutrient levels by casting nutrient-rich pellets into the water.
Conservation Efforts The history of conservation efforts for
the Devils Hole pupfish is instructive. The Devils Hole unit was added to Death
Valley National Monument by presidential proclamation in 1952. Ten years later
the NPS installed a hydrograph in the Hole to monitor water levels.
Subsequently, the Hole was fenced after two divers drowned in its water. In 1967
the Devils Hole pupfish was officially listed as an endangered species.
New Threats That same year saw a farming corporation
amass 12,000 acres in the Ash Meadows area; by 1968 the hydrograph had begun
to register a decline as large capacity wells were drilled and pumped in Ash
Meadows. The alarming water drop threatened to expose the critical
spawning/feeding shelf and precipitated the formation of two groups to work for
protection of Devils Hole: the Desert Fishes Council in the West, and the
Desert Pupfish Task Force in Washington D.C.
By 1970, drastic conservation efforts had been undertaken: refugia populations
were established, and a floating artificial shelf, artificially lighted,
was suspended in Devils Hole to substitute for the partially exposed
natural rock shelf. The fish never used the artificial shelf. In August 1971 a
federal court issued an injunction to halt further pumping, that threatened to
completely expose the natural shelf. Further litigation finally resulted in
the landmark Supreme Court decision of 1976. It recognized the prior water
right of Devils Hole vis-a-vis its designation as part of a national
monument. The permanent injunction did not halt pumping, but limited it to a
level which guaranteed sufficient water to inundate the natural rock shelf.
Recovery In their Devils Hole pupfish recovery
plan of 1980 the U.S. Fish and Wildlife Service designated as essential habitat
about 21,000 acres where the groundwater most influenced the water level in the
Hole. One of the identified goals of the recovery plan was to maintain the
aquifer at such levels that the population fluctuates from 300 in winter
to 700-900 in late summer. The water source for the Devils Hole pupfish was
now adequately secured, but the remainder of Ash Meadows was as yet
unprotected. A land development company bought the Ash Meadows land from the
farm corporation in 1977, planning to subdivide the area into 30,000
residential lots. This new threat to the Ash Meadows region prompted California
Senator Alan Cranston to introduce legislation in 1981 which would
establish a Desert Pupfish National Wildlife Refuge. Furthermore, in 1982
the U.S. Fish and Wildlife Service emergency-listed as endangered two more
of the fish species in Ash Meadows, thereby conferring protection to all
three levels of pools in the area. Finally, in 1984 Ash Meadows National
Wildlife Refuge was established by Congress. The Nature Conservancy bought
the bulk of the land from the development company and resold it to the
USFWS. By 1986 the USFWS had drafted a recovery plan for the entire Ash Meadows
area, including Devils Hole. A Mysterious Decline
Starting in the mid-1990s, the Devils Hole pupfish population began what was
to become a severe decline. Studies have been undertaken to better understand
energy flow in the system, water chemistry, pupfish genetics, organisms
living in the water, and other factors. Although the decline’s cause has not yet
been determined, knowledge of the Devils Hole ecosystem has been greatly
extended. Efforts continue to save this species that has existed for ten
thousand years. See also
Pupfish Cyprinodon - Genus
Amargosa Pupfish Station References
Landwehr, J.M. and Winograd, I.J., 2012, Devils Hole, Nevada—A Primer: U.S.
Geological Survey Fact Sheet 2012–3021, 6 p., available online at
http:pubs.usgs.gov2012/3021. External links
"Devils Hole". Geographic Names Information System. United States
Geological Survey. Retrieved 2009-08-10. The Southwestern Naturalist: "Pupfish
Populations"