There are over 1000 described species in the United States that are obligate cave dwellers, and several times that number in Europe.   We have launched an ambitious project of mapping this biodiversity with the goals of identifying subterranean biodiversity hotspots for protection and of understanding the pattern itself.   The database, with more than 8000 records, is maintained in Microsoft Access©, and mapping is done using ArcMap©.   Previous work has focused on the relationship between species richness and habitat availability, causes of regional differences in subterranean fauna, and the bias introduced by differences in sampling intensity.   Current projects include mapping and describing the pattern of single site endemics, a comparison of the U.S. and European cave fauna, and predictive models for the location of hotspot caves.

 

Christman, M.C., and D.C. Culver.   2001.   The relationship between cave biodiversity and available habitat.   Journal of Biogeography 28:367-380.

Culver, D.C.,   M.C. Christman, W.R. Elliott, H.H. Hobbs III, and J.R. Reddell.   2003.   The North American obligate cave fauna:   regional patterns.   Biodiversity and Conservation 12:441-468.

Culver, D.C., M.C. Christman, B. Sket, and P. Trontelj.   2004.   Sampling adequacy in an extreme environment:   species richness patterns in Slovenian caves.   Biodiversity and Conservation, 13: 1209-1229

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Project:   Epikarst--An Underappreciated and Unknown Habitat

In regions with soluble rock, especially limestone, a landscape formed largely by the dissolution of rock rather than erosion, often forms.   Characterized by sinkholes, sinking streams, caves, and springs, such a landscape is called karst.   The skin of the karst, the boundary between soil and rock, often has many small channels and voids, some of which are air filled and some of which are water filled.   This epikarst habitat is exceptionally difficult to sample and exceptionally rich in species.   In conjunction with Dr. Anton Brancelj of the National Institute of Biology in Slovenia and Dr. Tanja Pipan of the Karst Research Institute of Slovenia, I am beginning to investigate this habitat in the Appalachians.   The species are typically collected in specialized nets from drips in the ceiling of caves.   We have found over 20 species, at least 5 of which are obligate subterranean species.   This work will continue both in the Appalachians and in Slovenian caves.

Jones, W.K., D.C. Culver, and J.S. Herman [eds.]. 2004. Epikarst. Karst Waters Institute Spec. Publ. 9, Charles Town, WV.

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Project:   The Subterranean Amphipods of the Potomac River Coastal Plain

In The groundwater of the Coastal Plain of the Potomac River is home to an exceptionally diverse community of amphipods.   It includes six species of the genus Stygobromus :   S. hayi Holsinger , S. indentatus (Holsinger) , S. kenki Holsinger , S   phreaticus Holsinger , S. pizzinnii (Shoemaker) , S. tenuis potomacus (Holsinger) , and a new undescribed species.   All of these species are found only in groundwater, and nearly all records of these species are from national park lands.   Three species are endemic to the Washington, DC metropolitan area.   S. hayi is on the endangered species list, and the even rarer S. kenki has been petitioned for inclusion as well.   Nowhere else in the country except for the Edwards Aquifer in Texas is there an equivalent concentration of groundwater amphipods.

The groundwater habitats occupied by Stygobromus are both fragile and fragmented at local and regional scales.   They are found in seeps and small springs, called "hypotelminorheic" habitats by the groundwater ecologists.   These seeps and small springs are tiny aquifers, typically lined by a layer of clay, limited to a depth of a meter or so, and draining area of only a few hundred or thousand square meters.   Some of the Stygobromus species also occur in the underflow of spring runs and tributaries of the Potomac--the hyporheic habitats.   Stygobromus may occur in the hyporheic of the Potomac itself.

Stygobromus occurring in the Potomac Coastal Plain are vulnerable to several threats.   Because of their small area and superficial aspect, seeps and small springs are vulnerable both to spills and chronic contamination from road chemicals and lawn chemicals.   An increase in impermeable surfaces has   negative impacts due to reduction in recharge areas.   Even the placement of trails may eliminate or degrade a seep because of compaction.   Hyporheic habitats are at risk from contaminant spills and especially from storm water runoff.   Storm water runoff clogs spaces in hyporheic habitats, thus degrading the habitat.

In conjunction with the National Park Service, we are expanding the records for species occurrences, assess risks, and help create management plans for this remarkable fauna.