David C. Culver

American University | AU · Environmental Science

Iron Formations (IF) are threatened by mining, particularly the Mesovoid Shallow Substratum (MSS), an understudied subterranean environment. We evaluate the spatiotemporal patterns of subterranean fauna in MSS of iron duricrust (canga) in the Iron Quadrangle and Southern Espinhaço Range, southeastern Brazil. Samplings took place between July 2014 a...

We describe a new species of subterranean amphipod (Amphipoda: Crangonyctidae) in the genus Stygobromus from a hypotelminorheic seepage spring at Shepherd Parkway, part of National Capital East Parks, Washington, D.C., USA, part of the National Park System, using both morphological and genetic approaches. The Anacostia Groundwater Amphipod, S. anac...

Iron Formations (IF) are among the most threatened environments due to the extensive mining activities. Mesovoid Shallow Substratum (MSS) in IF represents a poorly known subterranean environment and evaluating its fauna has the potential for expanding knowledge about the distribution of troglobiotic populations. We evaluated the spatiotemporal dist...

Groundwater is a vital ecosystem of the global water cycle, hosting unique biodiversity and providing essential services to societies. Despite being the largest unfrozen freshwater resource, in a period of depletion by extraction and pollution, groundwater environments have been repeatedly overlooked in global biodiversity conservation agendas. Dis...

The study of subterranean life in general and cave life in particular has been given several names, most especially biospeleology and speleobiology. Historically, biospeleology came first, and signalled that biological study was part of speleology, the science of caves. Speleology itself has come to have several meanings beyond the science of caves...

The Western Balkan’s Vjetrenica Cave in southern Bosnia and Herzegovina is renowned for high richness of subterranean species. However, the data on its fauna have been published only in monographs printed in a small number of copies, making them hardly accessible to the wider scientific community. To overcome this issue, we compiled the data from p...

Twelve seepage springs in a 3 km ² area of the Goldmine Tract in the C&O Canal National Historical Park in Montgomery County, Maryland, USA were sampled in 1994–1995 and again in 2023 for three amphipod species: Stygobromus tenuis potomacus , Stygobromus pizzinii , and Crangonyx shoemakeri . During that time interval, there were 11 colonizations an...

Subterranean biology has a rich history of a special terminology used to describe the ecological distribution of subterranean species, their mode of colonization and speciation, and their morphology. This special terminology has several sources, including the exotic nature of the habitats, the often bizarre morphology of their inhabitants, as well...

Throughout the evolutionary tree, there are gains and losses of morphological features, physiological processes, and behavioral patterns. Losses are perhaps nowhere so prominent as for subterranean organisms, which typically show reductions or losses of eyes and pigment. These losses seem easy to explain without recourse to natural selection. Its m...

Groundwater is a vital ecosystem of the global water cycle, hosting unique biodiversity and providing essential services to societies. Despite being the largest unfrozen freshwater resource, in a period of depletion by extraction and pollution, groundwater environments have been repeatedly overlooked in global biodiversity conservation agendas. Dis...

For most plants and animals the broad outlines of global species richness are well known, and often in some detail [...]

Subterranean ecosystems are among the most widespread environments on Earth, yet we still have poor knowledge of their biodiversity. To raise awareness of subterranean ecosystems, the essential services they provide, and their unique conservation challenges, 2021 and 2022 were designated International Years of Caves and Karst. As these ecosystems h...

Brazil’s caves, home to diverse species and minerals, were stripped of protections by a recent presidential decree.

The hypotelminorheic is a groundwater‐fed shallow subterranean habitat, occurring a few metres below the surface and emerging at a seepage spring. Little is known about the habitat requirements for the amphipods and isopods that live there, and forest quality and other surface parameters have been largely unexplored. Urban parks, encompassing prote...

Riding a wave of interest in biodiversity patterns in surface-dwelling communities, in 2000, Culver and Sket [1] published a paper listing 20 caves and karst wells with 20 or more known species. [...]

Relative humidity (RH) was measured at hourly intervals for approximately one year in two caves at seven stations near Playa del Carmen in Quintana Roo, Mexico. Sistema Muévelo Rico is a 1.1 km long cave with 12 entrances and almost no dark zone. Río Secreto (Tuch) is a large river cave with more than 40 km of passages, and an extensive dark zone....

Relative humidity (RH) was measured at hourly intervals for approximately one year in two caves at seven stations near Playa del Carmen in Quintana Roo, Mexico. Sistema Muévelo Rico is a 1.1 km long cave with 12 entrances and almost no dark zone. Río Secreto (Tuch) is a large river cave with more than 40 km of passages, and an extensive dark zone....

Many questions relevant to conservation decision‐making are characterized by extreme uncertainty due to lack of empirical data and complexity of the underlying ecologic processes, leading to a rapid increase in the use of structured protocols to elicit expert knowledge. Published ecologic applications often employ a modified Delphi method, where ex...

Subterranean ecosystems include a wide variety of aphotic, often resource-poor sites, including caves, aquifers, and the underflow of rivers. This article discusses the kinds of subterranean ecosystems, the unique organisms that inhabit them, the colonization of the subterranean domain, the evolution and adaptation of these organisms, the geographi...

a. Aim—We describe the hydrological functioning and physical structure of epikarst, as well as the organisms that inhabit it. b. Main concepts covered—Epikarst is a nearly ubiquitous highly fractured zone at the top of karst that retains water from soil infiltration. Inhabited by both aquatic and terrestrial species, the aquatic copepod fauna is of...

Hourly temperature was measured for approximately one year at 17 stations in three caves in Quintana Roo, Mexico. Thirteen of these stations were in the extensive twilight zones of all three caves. All seventeen stations showed seasonality in temperature with a 3°C drop during the Nortes season. Two of the caves, Muévelo Sabrosito and Muévelo Rico,...

Five decades ago, a landmark paper in Science titled The Cave Environment heralded caves as ideal natural experimental laboratories in which to develop and address general questions in geology, ecology, biogeography, and evolutionary biology. Although the 'caves as laboratory' paradigm has since been advocated by subterranean biologists, there are...

Hourly temperature was measured for approximately one year at 17 stations in three caves in Quintana Roo, Mexico. Thirteen of these stations were in the extensive twilight zones of all three caves. All seventeen stations showed seasonality in temperature with a 3 °C drop during the Nortes season. Two of the caves, Muévelo Sabrosito and Muévelo Rico...

The general hypothesis that the overall presence or absence of one or more species in an extreme habitat is determined by physico-chemical factors was investigated using epikarst copepod communities as a model system, an example of an extreme environment with specialized, often rare species. The relationship between the presence or absence of epika...

Worldwide, caves and groundwater habitats harbor thousands of species modified and limited to subterranean habitats in karst. Data are concentrated in Europe and USA, where a number of detailed analyses have been performed. Much less is known with respect to global patterns due to a lack of data. This special issue will focus on and discuss the glo...

Karst aquifers are hydraulic structures where dissolution conduits dictate complex spatial and temporal flow patterns. These aquifers are vertically divided into phreatic, epiphreatic and vadose zones. While the phreatic zone is permanently saturated, providing the major contribution to base flow, most of the flood event water is transferred throug...

In karst areas, underground water mainly flows through conduits and fissures due to the solubility of carbonate rocks (Palmer in Cave geology. Cave Books, Dayton, Ohio, p. 454, 2007).

For understanding geological structure of karst areas (Palmer in Cave geology, Cave Books, Dayton, Ohio, p 454, 2007) it is inevitably to have detailed geological maps.

In this chapter, we review the status of the hypothesis that the dichotomy between shallow and deep subterranean habitats is a fundamental one, updating the original book-length presentation of this hypothesis (Culver and Pipan 2014), and consider the status of dim light habitats, such as leaf litter and partially de-roofed caves (Mejía-Ortíz et al...

Around 13% of the Earth’s surface is covered by carbonate rocks, on which a specific karst landscape with extensive underground water system develops.

About 44% of Slovenia’s surface consists of carbonate rocks. Karst geomorphology and over 13,000 known caves represent a significant proportion of its landscape. Various sediments present on the karst surface in the form of clastic or precipitated deposits can cover or fill smaller or extended areas and they can also accumulate in the caves.

In Western Slovenia, a paleokarstic surface with clayey bauxite deposits separates late? Cenomanian to late Turonian strata from middle/late Coniacian palustrine?, peritidal and shallow-marine carbonate deposits along the external-most preserved parts of the Adriatic Carbonate Platform (AdCP).

The rock relief of karst phenomena is often a revealing and graphic trace of their formation and development. It is composed of rock forms.

Quantification of present-day fundamental chemical processes in caves (dissolution and calcite precipitation) can provide basic objective information on rates, make possible comparison with other speleogenetic processes, and provide insights into spatial and temporal variability as well as factors controlling both processes.

This chapter introduces Škocjanske jame (Škocjan Caves) and their immediate karstic surroundings to those who are not already familiar with the place, and its overall history over several centuries.

Research data management planning is a key practice in science today, with a fundamental role in the organisation, use and reuse of research data, as well as in the verification of results.

Caves represent a discontinuity in a rock matrix and are considered as “dark openings” into the underground. Typical cave features—voids, cracks, fissures, or conduits—are filled with air (or mixture of various gases), water, or solid inorganic and/or organic material.

In light of recent alarming trends in human population growth, climate change, and other environmental modifications, a "Warning to humanity" manifesto was published in BioScience in 2017. This call reiterated most of the ideas originally expressed by the Union of Concerned Scientists in 1992, including the fear that we are "pushing Earth's ecosyst...

Troglobionts are organisms that are specialized for living in a subterranean environment. These organisms reside prevalently in the deepest zones of caves and in shallow subterranean habitats, and complete their entire life cycles therein. Because troglobionts in most caves depend on organic matter resources from the surface, we hypothesized that t...

Scientists of different disciplines have recognized the valuable role of terrestrial caves as ideal natural laboratories in which to study multiple eco-evolutionary processes, from genes to ecosystems. Because caves and other subterranean habitats are semi-closed systems characterized by a remarkable thermal stability, they should also represent in...

Colonization and speciation in subterranean environments can be conveniently divided into four stages. The first step is colonization of subsurface environments. There is a constant flux of colonists into most subterranean habitats. The second step is the success (or failure) of these colonizations. The third step is speciation. Under the Climate R...

A critical factor of the subterranean fauna and one that increases the risk of extinction is geographical rarity. Some stygobionts and troglobionts are also numerically rare. Subterranean organisms are also at increased risk of extinction because of low reproductive rates, and in the case of bats, because of their propensity to cluster in large num...

An important aspect of all aquatic subterranean ecosystems is the nature and connectivity of surface inputs. A theme common to both is heterogeneity of inputs that exist at even the smallest scale. At least in cave streams, carbon appears to be limiting. Studies at the scale of entire caves are of two very different kinds. For caves with surface in...

A wide variety of organisms are found in subterranean habitats and they have varying degrees of dependence and permanence in these habitats. Some species, stygobionts and troglobionts, have an obligate dependence on subterranean habitats, and are found nowhere else. Other species have an obligate dependence on caves and other subterranean habitats,...

The main subterranean habitats are: small cavities—interstitial spaces beneath surface waters; large cavities—caves; and shallow subterranean habitats—voids of various sizes close to the surface. The defining feature of all these habitats is the absence of light. Environmental variation is also reduced and most subterranean habitats rely on nutrien...

The loss of characters, especially eyes and pigment, in subterranean animals has attracted the attention of biologists since their first discovery centuries ago. Adaptationist ideas with regard to subterranean organisms were originally developed, not in connection with loss of eyes and pigment, but rather in connection with constructive changes suc...

Globally, for troglobionts, southern Europe, especially the Dinaric karst, and the Canary Islands are regions of high richness. For stygobionts, southern Europe, especially the Dinaric karst, is a hotspot. Other sites are typically chemoautotrophic and/or phreatic. In Europe and North America, there appears to be a ridge of high troglobiotic and st...

Among shallow subterranean habitats, representative communities of hypotelminorheic (Lower Potomac seeps, Washington, DC), epikarst (Postojna–Planina Cave System, Slovenia), milieu souterrain superficiel (MSS) (central Pyrenees, France), soil (central Pyrenees, France), calcrete aquifers (Pilbara, Western Australia), lava tubes (Tenerife, Spain and...

Although subterranean habitats in general and caves in particular are often held to be extremely energy-poor (oligotrophic) environments, not all are. Compared to surface habitats, subterranean habitats are nutrient-poor, especially because there is no photo-autotrophic production and chemoautotrophy appears to be uncommon. On the other hand, these...

Caves and other subterranean habitats with their often strange (even bizarre) inhabitants have long been objects of fascination, curiosity, and debate. The question of how such organisms have evolved, and the relative roles of natural selection and genetic drift, has engaged subterranean biologists for decades. Indeed, these studies continue to inf...

A general pattern emerges from studies of subterranean communities. At a regional scale, hydrogeological and historical factors exert a controlling influence on many species, and the importance of species interactions is small. This is the pattern of the Jura Mountain groundwater communities. At a smaller geographical scale, there is little variati...

Worldwide, there are at least 12 ILTER sites with an emphasis on karst, landforms arising from the combination of high rock solubility and well-developed solutional channel porosity underground, but the study of cave ecosystems has been largely neglected. Only two ILTER sites, both in Slovenia, are primarily caves. Caves are under-represented for s...

The ability of three amphipods that occupy shallow subterranean habitats in the lower Potomac Basin of the US (hypotelminorheic), which often dry out seasonally, to withstand desiccation by burrowing in clay was investigated. Both Crangonyxshoemakeri , a wetland species, and Stygobromustenuis , a subterranean species, burrowed in clay in the labora...

Evolutionary processes, including natural selection, neutral mutation, and habitat filtering, act upon morphology and other aspects of their biology, as well as species composition itself, to produce the observed patterns or community structure and morphology. The context for these evolutionary processes (the ecological theater in G.E. Hutchinson’s...

Over 150 sites in parklands of southeast Washington, D.C. were examined for the presence of inhabitants of seepage springs and associated groundwater habitats—the hypotelminorheic. Three species predominated—the isopod Caecidotea kenki and the amphipods Crangonyx shoemakeri and Stygobromus tenuis sensu lato. C. shoemakeri and Stygobromus rarely occ...

Effective conservation and management of biodiversity is limited by a lack of critical knowledge on species’ distributions and abundances. This problem is particularly exacerbated for species living in habitats that are exceptionally difficult to access or survey, such as ground- water habitats. Environmental DNA (eDNA) represents a rapid, noninvas...

The decomposition of diversity into within site (α) and between site (β) components is especially interesting in subterranean communities because of their isolated nature and limited dispersal potential The aquatic epikarst fauna, sampled from water drips in caves affords a unique opportunity to provide comparable, quantitative samples of a portion...

Number of copepods found, by species and by drip, in the study caves of the Isolated region. (XLSX)

Numbers of copepods found, by species and by drip, in the study caves of the Dinaric region. (XLSX)

Number of copepods found, by species and by drip, in the study caves of the Alpine region. (XLSX)

The first cave‐dwelling invertebrate known to science was the beetle Leptodirus hochenwartii, described by Ferdinand Schmidt in 1832. This chapter presents a discussion of L. hochenwartii. It describes the variety of subterranean spaces, including but not limited to caves, that insects inhabit, the ecological roles of insects in subterranean habita...

The West Virginia cave fauna includes species that leave caves periodically to forage (cave crickets and bats) as well as permanent inhabitants (both species that are limited to caves [troglobionts] and ones that occur elsewhere [troglophiles]). Troglobionts are the best studied, but troglophiles predominate in many caves. Major sources of food for...

The Greenbrier Karst harbors 16 species of stygobionts known from 92 caves, and six of these caves are type localities of ten of the species. The fauna is dominated by crustaceans and especially amphipods of the genus Stygobromus, and they primarily occupy vadose streams and the epikarst, but are notably absent from phreatic waters. Stygobromus spi...

Sistema Muévelo Rico is a 1.2 km long cave in Quintana Roo, less than 2 km from the Caribbean Sea. We measured illuminance to a level of 0.1 lux, organic matter (weight loss on ignition), temperature, and relative humidity. The last two were measured at hourly intervals for nearly one year. Approximately one-third of the cave has illuminance values...

In the last two decades, there has been a substantial progress in the availability of records for several subterranean taxa, as well as in mapping and statistical modeling of biodiversity patterns. Currently, there is still a large bias toward analyses of aquatic compared to terrestrial subterranean taxa. We provide the first global map of species...

variety of subterranean habitats share an absence of light and a dependence on allochthonous productivity, but they differ in many features, including habitat volume. We examined the hypothesis that habitat volume is an important factor in community organization, especially with reference to body size, for a variety of communities for which data we...

Although primarily known as a journal of karst geosciences and hydrology, Acta Carsologica has played a vital role in the development of speleobiology. A total of 65 biological papers on speleobiology were published in the journal from 1955 to 2014. Many of the papers, especially in the early years of the journal, added to the knowledge base of spe...

Cave-limited species display patchy and restricted distributions, but are challenging to study in-situ because of the difficulty of sampling. It is often unclear whether the observed distribution is a sampling artifact or a true restriction in range. Further, the drivers of the distribution could be local environmental conditions, such as cave humi...

One of the most challenging fauna to study in situ is the obligate cave fauna because of the difficulty of sampling. Cave-limited species display patchy and restricted distributions, but it is often unclear whether the observed distribution is a sampling artifact or a true restriction in range. Further, the drivers of the distribution could be loca...

Maps of observed and predicted distribution of troglobiotic fish (genera Amblyopsis, Speoplatyrhinus and Typhlichthys) in the study area. A. Observed distribution of troglobiotic fish in 20 x 20 km grid. B. Predicted probabilities of occurrence of troglobiotic fish in those grid cells that have observed troglobionts. C. Predicted probabilities of o...

Maps of observed and predicted distribution of troglobiotic isopods (largely the genus Caecidotea) in the study area. A. Observed distribution of troglobiotic isopods in 20 x 20 km grid. B. Predicted probabilities of occurrence of troglobiotic amphipods in those grid cells that have observed troglobionts. C. Predicted probabilities of occurrence of...

Maps of observed and predicted distribution of troglobiotic crayfish (largely the genera Cambarus and Orconectes) in the study area. A. Observed distribution of troglobiotic crayfish in 20 x 20 km grid. B. Predicted probabilities of occurrence of troglobiotic crayfish in those grid cells that have observed troglobionts. C. Predicted probabilities o...

Maps of observed and predicted distribution of troglobiotic spiders (including Bathyphantes, Liocrinoides, Nesticus, Phanetta, and Porrhomma) in the study area. A. Observed distribution of troglobiotic spiders in 20 x 20 km grid. B. Predicted probabilities of occurrence of troglobiotic spiders in those grid cells that have observed troglobionts. C....

Maps of observed and predicted distribution of troglobiotic springtails (including Pseudosinella, Pygmarrhopalites, and Sinella) in the study area. A. Observed distribution of troglobiotic millipedes in 20 x 20 km grid. B. Predicted probabilities of occurrence of troglobiotic millipedes in those grid cells that have observed troglobionts. C. Predic...

Maps of observed and predicted distribution of troglobiotic millipedes (genera Pseudotremia, Scoterpes, Zygonopus, and others) in the study area. A. Observed distribution of troglobiotic millipedes in 20 x 20 km grid. B. Predicted probabilities of occurrence of troglobiotic millipedes in those grid cells that have observed troglobionts. C. Predicte...

Maps of observed and predicted distribution of single grid endemics in the study area. A. Observed distribution of troglobiotic endemics in 20 x 20 km grid. B. Predicted probabilities of occurrence of troglobiotic endemics in those grid cells that have observed troglobionts. C. Predicted probabilities of occurrence of troglobiotic endemics in all g...

We investigated the upper and lower vertical limits of the distribution of inhabitants of the most abundant freshwater habitat—groundwater. Distribution in photic habitats is limited by competition, predation, and risks of exposure to ultraviolet radiation. Nonetheless, a number of eyeless, depigmented subterranean species occur in twilight habitat...