Professor & Associate Dean of Sciences
Hurst Hall 12
voice 202.885.2180 | dculver@american.edu
Quick Links: CV | Culver Lab (under construction)
I am interested a wide variety of aspects of the biology of caves and other subsurface environments. I have done research on ecosystem services, species interactions, population regulation, evolution, adaptation, and biogeography in the subterranean realm. I have written several general books on subterranean life, most recently Encyclopedia of Caves, which I edited with William B. White published by Academic/Elsevier Press and Biology of Caves and Other Subterranean Habitats, written with Tanja Pipan, and to be published by Oxford University Press. My current research involves three aspects of the conservation biology of the subterranean biota.
Subterranean Biodiversity: There are over 1000 described species of obligate cae-dwelling animals in the United States and several times that number in Europe. Together with colleagues in Europe and the U.S., we are mapping and comparing biodiversity patterns in different regions. We have looked at the question of sampling adequacy and discovered broad scale patterns in both Europe and North America. This work continues at a meso-level scale with a more detailed analysis of patterns in West Virginia and to determine human impacts on this biodiversity in the last 50 years. .
- 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. [pdf]
- Culver, D.C., L. Deharveng, A. Bedos, J.J. Lewis, M. Madden, J.R. Reddell, B. Sket, P. Trontelj, and D. White. 2006. The mid-latitude biodiversity ridge in terrestrial cave fauna. Ecography 29:120-128. [pdf]
- Zagmajster, M., D.C. Culver, and B. Sket. 2008.
Species richness patterns of obligate subterranean
beetles in a global biodiversity hotspot - effect of
scale and sampling intensity. Diversity and Distributions
14:95-105.[pdf]
Superficial Subterranean Habitats: The standard view of subterranean habitats is that they are food-poor, aphotic, and without temporal cues, making successful colonization extremely difficult. Superficial subterranean habitats do not fit this paradigm. A variety of habitats, including talus slopes and regolith, superficial ground emerging in small seeps, and cracks, fissures, and shallow tubes in lava, are aphotic, but with relatively high resources and temporal variability. All of these habitats harbor species modified for subterranean life (eyeless and without pigment, and with elongated appendages), similar to species found in caves. This suggests that the absence of light is the primary selective factor in the evolution of the distinctive morphology of cave animals, and that species in superficial subterranean habitats may give rise to species in deeper subterranean habitats such as caves. Colonization of superficial subterranean habitats may be the result of adaptive shifts or the result of unfavorable conditions in surface habitats. Work to characterize these habitats is continuing, both in the Washington, DC area (seeps), West Virginia caves (the skin of karst—epikarst), and in Slovenia (talus slopes).
- Pipan T., Christman M.C. and Culver D.C. 2006. Dynamics of epikarst communities: microgeographic pattern and environmental determinants of epikarst copepods in Organ Cave, West Virginia. American Midland Naturalist 156:75-87. [pdf]
- Culver, D.C., T. Pipan, and S. Gottstein. 2006. Hypotelminorheic—a unqiue freshwater habitat. Subterranean Biology 4:1-8. [pdf]
- Pipan, T., and D.C. Culver. 2007. Copepod
distribution as an indicator of epikarst system
connectivity. Hydrogeology Journal 15:817-822. [pdf]
Caves as Ecosystems: It has long been recognized that caves and other subterranean habitats are likely to be food-limited because of the absence of photosynthesis. There is a great deal of indirect evidence such as reduced metabolic rate, larger but fewer eggs, and increased longevity of subterranean animals that is consistent with the hypothesis of resource limitation. However, there has been remarkably little direct measurement of the input to and subsequent use of energy in caves. The lack of emphasis by speleobiologists on the flux of food, especially organic carbon, is all the more remarkable because the discipline of ecology was revolutionized in the 1950’s and 1960’s by the introduction of ecosystem concepts. Perhaps the most important advance of ecosystem ecology was re-parameterization. Instead of a focus on numbers of individuals, numbers of species, and the like, systems ecology focused on standing stocks and fluxes of matter and energy (especially carbon, phosphorus, nitrogen).
We developed a conceptual model for the movement of organic carbon through a karst basin. There are three main inputs—(1) localized flow of particulate organic carbon (POC) and dissolved organic carbon (DOC) through sinks and shafts (2) diffuse flow of POC and DOC from soils and epikarst, and (3) deep groundwater inputs. We measured inputs of the first two in Postojna-Planina Cave System Slovenia and Organ Cave in Wst Virginia. Most DOC enters through streams entering the cave but diffuse flows from soils and epikarst is more generally distributed and appears to play an important role in subterranean food webs. We detected considerable spatial variation in DOC among epikarst drips, and these differences were consistent through time. DOC concentration was a good predictor of the abundance of copepods in dripping water, which in turn is a measure of community abundance in epikarst. Current work is focused on estimating differences in both quantity and quality of organic carbon in various fluxes.
- Simon, K.S., T. Pipan, and D.C. Culver. 2007. A
conceptual model of the flow and distribution of organic
carbon in caves. Journal of Cave and Karst Studies
69:279-284. [pdf]