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Southwest caves reveal new forms of life

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Abstract

Caves in northern Arizona and western New Mexico are being researched and inventoried by scientists with the U.S. Geological Survey and cooperating agencies. Southwestern caves have been little studied, and scientists are now finding that these lightless and nutrient-poor natural systems are home to life forms found nowhere else on Earth. This research has identified unique communities of arthropods (insects, arachnids, and crustaceans) that include 3 new genera, or groups of species, and at least 15 new species— some only known to exist in a single cave. This exciting research is yielding information that will be used by resource managers to better understand and protect fragile and important Southwestern cave ecosystems.
aves in northern Arizona and
western New Mexico are be-
ing researched and inventoried by
scientists with the U.S. Geological
Survey and cooperating agencies.
Southwestern caves have been
little studied, and scientists are
now finding that these lightless
and nutrient-poor natural systems
are home to life forms found no-
where else on Earth. This research
has identified unique communities
of arthropods (insects, arachnids,
and crustaceans) that include 3
new genera, or groups of species,
and at least 15 new species—
some only known to exist in a
single cave. This exciting research
is yielding information that will be
used by resource managers to bet-
ter understand and protect fragile
and important Southwestern cave
ecosystems.
C
Southwest Caves Reveal New Forms of Life
U.S. Department of the Interior
U.S. Geological Survey
USGS Fact Sheet 2009–3024
2009
Few caves in any region of the
world have been studied at an ecosys-
tem level, and the caves of the south-
ern Colorado Plateau—the Four Cor-
ners region of the Southwestern United
States—are no exception. Scientists
from the U.S. Geological Survey
(USGS), Northern Arizona University,
National Park Service, and Bureau
of Land Management have begun an
effort to inventory and study caves in
northern Arizona and western New
Mexico. The research team is not only
studying the physical environments
found in caves but also documenting
their biodiversity.
When it comes to the American
Southwest, many people think of the
desert as the region’s ultimate chal-
lenging environment, but a South-
western cave may be an even more
extreme environment than the above-
ground desert. Isolated from light
A scientist explores a recently discovered cave in Grand Canyon-Parashant National Monument, Arizona. This
desert cave is unusual because it has numerous standing pools of water. (Photograph courtesy of Jon Jasper,
Bureau of Land Management, and Kyle Voyles, National Park Service.)
A breeding pair of cave crickets that belongs to a genus new to science. U.S. Geological Survey scientists and
their cooperators recently discovered the crickets in Grand Canyon-Parashant National Monument, Arizona. (Pho-
tograph courtesy of Kyle Voyles, National Park Service.)
In cooperation with Northern Arizona University Merriam-Powell Center for
Environmental Research, National Park Service, and Bureau of Land Management
and vegetation, caves are inherently
nutrient starved and rely on inputs
from the surface to support life under-
ground. Cave dwellers like bats and
crickets “import” nutrients by feed-
ing outside of caves and returning to
deposit guano, or feces. Guano can
be a critical part of the food web in
cave environments. Other nutrients
are brought into caves when ooding
or wind carries vegetation and other
organic material into caves.
Not only are Southwestern caves
nutrient poor, but also water is often
scarce. Those subterranean pools and
streams that do exist in caves can be
oases for cave-adapted species.
Despite being extreme environ-
ments, caves shelter a wide range
of life. Some cave animals such as
bats live part of their lives outside
of caves, and some creatures never
leave them. For example, “troglo-
bites” are animals that spend their
entire lives underground and may
include invertebrates such as spiders,
insects, and millipedes. Aquatic tro-
globites called “stygobites” include
animals such as shrimp, craysh, and
sh.
Cave-adapted animals have
interesting evolutionary adaptations
that reect the extreme environments
found in caves. These animals often
lack skin pigmentation and eyes and
have elongated appendages that help
them to move more efciently, thus
conserving energy. Troglobitic inver-
tebrates may also have longer hairs,
or “setae,” and antennae than their
surface counterparts that help them
sense their surroundings in complete
darkness.
Microbes are some of the organ-
isms best adapted to life in caves.
Some microbes can feed on the
minerals found on rocks or within
subterranean pools, and others
even lter nutrients from the air.
These tiny organisms can be very
important to cave ecosystems—in
some cases, microbes can serve as
the center of a cave’s food web.
To better understand and document
cave ecosystems, scientists have
developed an inventory protocol
based on the most effective tech-
niques of specimen collection and
random sampling to better character-
ize cave environments.
As of March 2009, USGS
scientists and their cooperators
have identied 3 new invertebrate
genera—a millipede, a cricket, and
a barklouse—and at least 15 new
species of arthropods from caves in
northern Arizona.
Pools and streams in caves are
proving to be good places to look for
new forms of life. USGS researchers
have found a new species of amphi-
pod, a small shrimp-like crustacean,
in a stream cave in Grand Canyon,
Arizona, that is not known to exist
anywhere else on the planet. Scientists
may also have identied a new species
of copepod, a small crustacean, in sub-
terranean pools in a cave on the north
rim of Grand Canyon.
Cave dwellers and cave environ-
ments are proving to be fragile. For
example, pregnant female bats congre-
gate in the early summer at roost sites,
known as maternity roosts, to bear
For more information contact:
U.S. Geological Survey
Southwest Biological Science Center
Colorado Plateau Research Station
Flagstaff, Arizona
928-523-9080 or
Jut.Wynne@nau.edu
Charles_Drost@usgs.gov
This Fact Sheet and any updates to it are available
online at http://pubs.usgs.gov/fs/2009/3024/
and raise their pups. Even seemingly
harmless activities, such as shining
a light into a maternity colony, may
cause some species of bats to leave
their roosts and abandon their pups.
Bat populations are of special concern
because they are in decline worldwide.
These winged mammals are impor-
tant pollinators and seed dispersers
and help to control agricultural insect
pests. To limit their impacts on caves,
researchers schedule their investiga-
tions at times when bat maternity
roosts are not in use, or they wait until
the bats have left for the night before
they begin work in the cave.
The discovery of new species and
communities of organisms living in
cave environments may help scientists
piece together the unique natural sys-
tems that Southwestern caves support.
New research and recent discoveries
help to underscore the importance of
cave ecosystems. USGS scientists
are working cooperatively with land
managers to develop biodiversity
inventory and monitoring strategies
and ways to monitor visitor impacts
on caves. Expanding the body of
knowledge available to land manag-
ers about cave ecosystems in the
American Southwest is an important
step toward conserving these fragile
natural systems.
This tiny barklouse, measuring only 1. 3 millimeters (smaller than a grain of rice), represents a new
genus. It was recently discovered from a cave in Grand Canyon-Parashant National Monument,
Arizona. (Photograph courtesy of Ed Mockford, Illinois State University.)
This eyeless cave-limited millipede represents
a new genus, Pratherodesmus, and is helping
scientists better understand cave ecosystems.
(Photograph courtesy of Bern Szukalski, Cave
Research Foundation.)
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