There are numerous anthropogenic activities which may affect cave ecosystems. Impacts related to human use of caves, which may disrupt the functioning of ecosystems, include: (a) cave sediment compaction, which can reduce cave fauna productivity, reduce soil microhabitats and may lead to extinction of small, cryptic species (depending upon the degree of soil compaction and species' sensitivity); (b) introduction of molds and other micro-organisms, these organisms may place competitive or predation pressures on cave-dwelling animals; (c) introduction of lint from clothes, which serve as substrate and food source for molds, fungi and bacteria; (d) increase in carbon dioxide levels and ambient temperatures, can alter cave microclimates making the cave less hospitable to cave-dwelling animals, and; (e) nutrient stress related to cave abandonment by bats.

Impacts related to human surface activity include: (i) water diversion projects and over-pumping of the aquifer; (ii) land development via vegetation conversion, road development, and/ or mining; (iii) nutrient enrichment from agricultural fertilizers can adversely affect cave-dwelling animal populations; (iv) invasive species such as vertebrates, insects, fungi, and worms; and, (v) chemical effluents that run off the surface and into caves. Human water use and development can alter subsurface hydrology thus potentially changing cave microclimates and eliminating standing water within caves. Nutrient stress, invasive species and chemical effluents are direct threats to cave-dwelling animals. These impacts can alter the cave in ways that make it difficult for cave-dwelling animals to compete and persist.

Threats to Cave-Roosting Bats

In North America, cave-roosting bat populations have been in decline for over half a century. Bats have been disturbed and even killed throughout North America by humans due to numerous misconceptions and myths about these animals. Human disturbance has been identified as detrimental to caves containing roosting bat colonies including maternity/ nursery colonies and hibernacula. Activities as seemingly benign as briefly entering a roost area, or shining a light can result in permanent bat abandonment, decreased chances for survival, abandonment of the roost site and even death. If maternity roosts are entered or disturbed, some bat species (such as the lesser long-nosed bat (Leptonycteris yerbabuenae) of southeastern Arizona and southwestern New Mexico) are known to abandon the roost and their offspring.

Human use for both recreational and scientific activities is a well known culprit leading to the decline of bat populations.

The recent outbreak of White Nose Syndrome in the northeastern U.S. is particularly alarming. While little is known regarding this pathogen that is killing bats, all bats that have died have a characteristic white fungal growth on their noses. To date, bat deaths have been reported in New York, Vermont and Massachusetts. It appears the fungus may block the nasal passage making it difficult for the hibernating bat to breath. Researchers studying this condition suspect they may have been responsible for spreading this condition to other bat roosts. They now wear biohazard suits when entering caves in the Northeast to evaluate bats. Scientists have also requested that cavers refrain from going underground until they can learn more about this disease. While there have been no reports of White Nose Syndrome in the Southwest, researchers are remaining vigilant until more can be learned regarding this condition.

For more information on White Nosed Syndrome, refer to the National Public Radio Story, Northeast Bat Die-Off Mirrors Honeybee Collapse (19 February 2008).

Also, watch the NPR Science Friday Video Dead Bat Mystery (18 April 2008)

Threats to Other Cave Dwellers (Troglobites)

Troglobites and stygobites (troglomorphic cave-dwellers) are considered some of the most fragile and endangered species on Earth. These cave-adapted animals have evolved to exist in a nutrient-starved environment and often under a narrow set of environmental conditions. Some of these animals are endemic to a specific cave or region. Unlike bats, if their habitat is diminished by human activities, these animals have nowhere to go. Dramatic changes in their ecosystem, such as increased nutrient loading from agriculture or pollution or sedimentation, may cause some species to become extirpated from a cave or even globally extinct (if the organism is endemic to a specific cave).

Additionally, researchers do not know how cave-adapted organisms will respond to global climate change. We can reasonably suggest that those organisms persisting under the narrowest suite of environmental conditions may be most susceptible to becoming extinct. We further suggest, as was observed during the last glaciation, that certain organisms intolerant of rising surface temperatures may retreat underground. These new colonizers to the subterranean world may represent organisms on the evolutionary path toward troglomorphy.

Because many troglomorphs rely directly or indirectly upon the nutrients brought into the cave by bats (via guano), the proper management of healthy bat populations is vitally important to the persistence of many cave ecosystems. When bats abandon a cave (for whatever reason), other cave-dwelling animals become less common, and may even become extinct.