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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 greater than 0.01 lux, and most of the rest of the cave has light as well. Temperature and relative humidity were relatively constant, but they showed a daily cycle at all stations, albeit with different strengths. Organic matter averaged 8%, intermediate in value between surface and aphotic zones. Both eyeless species and eyed predators occurred throughout the cave. Their occurrence can best be explained by their foraging for organic matter and incurring an increased risk of predation.

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 groundwater habitats. Environmental DNA (eDNA) represents a rapid, noninvasive, and potentially cost-effective new tool for detection and monitoring of biodiversity that occur in such habitats. In this study, we investigated the utility of eDNA in detecting the federally endangered Hay’s Spring Amphipod Stygobromus hayi and a co-occurring common congener S. tenuis potomacus from unique groundwater-associated habitats—hypotelminorheic seepage springs—in the Washington, DC metro area. We developed taxon-specific primers and probes for each species to amplify Stygobromus DNA using qPCR. In silico and in vitro validation demonstrated specificity of each designed assay. Assays were then used to screen water samples collected from ten seepage springs. Stygobromus hayi was detected at four seepage springs, including one potential new locality, while S. t. potomacus was detected at four springs, two of which were new localities. This study is the first to our knowledge to successfully employ an eDNA approach to detect rare or threatened invertebrates from subterranean ecosystems. Our study highlights challenges of employing an eDNA approach for the detection and monitoring of invertebrates in groundwater habitats that are difficult to study, including accounting for PCR inhibition and the potential for cryptic genetic diversity.

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, such as bats and aquatic insects, but only spend part of their life cycle in caves (stygoxenes and trogloxenes). Others can spend their life cycle in or out of caves (stygophiles and troglophiles). There are 21 invertebrate orders that have over 50 stygobiotic and troglobiotic species. Among vertebrates, salamanders and especially fishes are also well represented in caves and deep aquifers. Although the information obtained is very informative, very few subterranean species have been maintained successfully in the laboratory. There are a few specialized collecting techniques that are very useful, especially in non-cave subterranean habitats.

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 such as appendage elongation and elaboration of extra-optic sensory structures. Three studies of adaptation epitomize adaptation as it applies to subterranean species. In Poulson’s study of life history and metabolic and neurological changes in cave fish, his basic approach was comparative, using related surface-dwelling species. Using quantitative genetics, Culver and colleagues studied the amphipod G. minus, focusing on the adaptation to the darkness of caves. Jeffery and colleagues focused on the causes of eye and pigment degeneration in the Mexican cavefish A. mexicanus. Using an array of techniques, they demonstrated the critical role pleiotropic selection plays.

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 inputs, inputs from percolation water are quantitatively less important than inputs from sinking streams, but are qualitatively more important because they occur throughout the cave and form the basis for the biofilm. Sulfur-oxidizing bacteria are the trophic base for most chemoautotrophic cave communities. Only two ecosystem studies of an entire karst basin have been carried out. For the Dorvan basin in France, most carbon entering the ecosystem is DOC, and there is considerable storage of organic carbon in sediments. In the Edwards Aquifer of Texas, chemolithoautotrophy contributes to all the components.

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 numbers in a few caves. Threats to the subterranean fauna are of four general kinds—alteration of the physical habitat, changes in water quality and quantity, direct changes to the subterranean fauna, and global warming. The selection of sites for preservation requires detailed inventory data, but available evidence suggests that a majority of species can be protected at least at one site and that a relatively small percentage of total land area is required. A variety of mechanisms are available for site protection, including listing as a Ramsar wetland and as a UNESCO world heritage site.

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 Relict Hypothesis (CRH) surface populations go extinct but under the Adaptive Shift Hypothesis (ASH) they do not necessarily do so, and speciation can be parapatric. There is strong evidence for the CRH among temperate zone fauna, and growing evidence for the ASH in tropical caves, especially lava tubes. The final step is possible further speciation as a result of subsurface dispersal. Detailed analysis of the evolutionary history of the isopod A. aquaticus in the Dinaric karst, diving beetles Paroster in a calcrete aquifer in Western Australia, and trogloxenic Leopoldamys neilli in Thailand reveal some of the complexities of species’ phylogeography.

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 inform the general theory of adaptation and evolution. Subterranean ecosystems generally exhibit little or no primary productivity and, as extreme ecosystems, provide general insights into ecosystem function. The Biology of Caves and other Subterranean Habitats offers a concise but comprehensive introduction to cave ecology and evolution. Whilst there is an emphasis on biological processes occurring in these unique environments, conservation and management aspects are also considered. The monograph includes a global range of examples from more than 25 countries, and case studies from both caves and non-cave subterranean habitats; it also provides a clear explanation of specialized terms used by speleologists. This accessible text will appeal to researchers new to the field and to the many professional ecologists and conservation practitioners requiring a concise but authoritative overview. Its engaging style will also make it suitable for undergraduate and graduate students taking courses in cave and subterranean biology. Its more than 650 references, 150 of which are new since the first edition, provide many entry points to the research literature.

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 variation in hydrogeological or historical factors. For example, in both the Slovenian epikarst and Lyon aquifer studies, there was little if any variation in hydrogeological or historical factors. Species did differ in their occurrence along physicochemical axes, and these differences may well be the result of competition. Finally, some intensively studied communities show high levels of competition and predation, so strong that divergence rather than convergence occurs. There remains a gap between these somewhat unusual species combinations (beetles and cricket eggs, Appalachian cave stream invertebrates, Dinaric Niphargus, Australian calcrete diving beetles) and the broader scale community studies.

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 nutrients transported from the surface. The aquatic component of caves includes water percolating from the surface (including epikarst), streams, and resurgences. Terrestrial habitats include epikarst, and the vadose zone. The aquatic interstitial habitat is comprised of the water-filled spaces between grains of unconsolidated sediments. Shallow subterranean habitats are ones close to the surface. They include the hypotelminorheic, interstitial, epikarst, MSS, soil, lava tubes, calcrete aquifers, and iron-ore caves. They share an absence of light, close surface connections, relatively high nutrient levels relative to other subterranean habitats, and the presence of species highly modified for subterranean life.

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 Lava Beds National Monument, California), fluvial aquifers (Lobau wetlands, Austria), and iron-ore caves (Brazil) are described. Among non-cave deeper habitats, communities of phreatic aquifers (Edwards Aquifer, Texas), and deep phreatic aquifers (basalt aquifers, Washington) are described. Among cave habitats, representative tropical terrestrial (Gua Salukkan Kallang, Sulawesi, Indonesia), temperate terrestrial (Mammoth Cave, Kentucky), chemoautotrophic (Peştera Movile, Romania), hygropetric (Vjetrenica, Bosnia & Herzegovina), anchialine (Šipun, Croatia), cave streams (West Virginia and U.K.) and springs (Las Hountas, Baget basin, France) communities are discussed.

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 stygobiotic diversity in southern Europe and the southeast United States that corresponds to an area of long-term high surface productivity. In Europe, local diversity is a small component of regional stygobiotic diversity and the importance of spatial heterogeneity, historical climate stability, and productivity are both scale and spatially dependent. Habitat availability seems especially important at smaller scales. The analogy with islands in ecological time is most appropriate at scales smaller than caves, such as seeps or epikarst drips, and the analogy with caves in evolutionary time is more appropriate at larger scales, such as karst basins or contiguous karst areas.

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 differences are not always pronounced. For example, the quantities of carbon fluxes in cave streams are in the range of those reported from surface streams. In some subterranean systems, chemoautotrophy is the main source of energy, but more typically subterranean communities depend on allochthonous sources of organic carbon. The major source of carbon in interstitial habitats is Dissolved Organic Matter (DOM) from surface waters. The major sources of carbon for cave communities are (1) water percolating from the surface, (2) sinking streams that enter caves, and (3) activities of animals moving in and out of caves.

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 ecosystems beyond their capacities to support the web of life.” As subterranean biologists, we take this opportunity to emphasize the global importance and the conservation challenges associated with subterranean ecosystems. They likely represent the most widespread nonmarine environments on Earth, but specialized subterranean organisms remain among the least documented and studied. Largely overlooked in conservation policies, subterranean habitats play a critical role in the function of the web of life and provide important ecosystem services. We highlight the main threats to subterranean ecosystems and propose a set of effective actions to protect this globally important natural heritage.

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 they would also select the sections of caves nearest the surface, as long as environmental conditions were favorable. Over 1 year, we analyzed, in monthly intervals, the annual distributional dynamics of a subterranean community consisting of 17 troglobiont species, in relation to multiple environmental factors. Cumulative standardized annual species richness and diversity clearly indicated the existence of two ecotones within the cave: between soil and shallow subterranean habitats, inhabited by soil and shallow troglobionts; and between the transition and inner cave zones, where the spatial niches of shallow and deep troglobionts overlap. The mean standardized annual species richness and diversity showed inverse relationships, but both contributed to a better insight into the dynamics of subterranean fauna. Regression analyses revealed that temperatures in the range 7-10 degrees C, high moisture content of substrate, large cross section of the cave, and high pH of substrate were the most important ecological drivers governing the spatiotemporal dynamics of troglobionts. Overall, this study shows general trends in the annual distributional dynamics of troglobionts in shallow caves and reveals that the distribution patterns of troglobionts within subterranean habitats may be more complex than commonly assumed.

With more than 5000 species described, European subterranean biodiversity is the highest in the world. This is in part due to a long history of scientific activities, but some evidence suggests that it is actually higher in Europe due to historical and physiographical factors. The knowledge of European fauna is poorer for subterranean habitats than for any other habitat. In the PASCALIS project, 40% of the stygobiotic fauna sampled in seven European sites was shown to be new to science. Several groups radiated extensively in Europe, particularly beetles and Niphargidae amphipods. Subterranean evolution also produced more troglomorphy in Europe than in any other continent. Relictualism is often associated with high troglomorphy, a number of European taxa having no close surface relatives. Cave diversity is unevenly distributed across the continent with a gradient in species richness dropping off to the north, as a result of extinctions due to quaternary glaciations and gradients of primary productivity. Biodiversity peaks on a mid-latitude ridge between 42° and 46° north: the major part of European troglobionts, troglomorphic, and relict taxa are on this ridge. On this ridge, two areas contain most of the remarkable cave taxa: the Dinaric range and the Pyrenees. The ratio of troglobionts to stygobionts declines with increasing latitude from the biodiversity ridge. At a finer scale, considerable changes in subterranean communities are linked to habitat characteristics, especially pore size.

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, showed greater variability during the winter months while in Rio Secreto variability was greatest during the rainy season. Río Secreto is less open to the surface than the other two. All sites also showed a daily temperature cycle, although it was very faint in some Rio Secreto sites. While temperature variability is diminished relative to surface variation, its temporal pattern is worthy of further study.

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 global patterns of individual hotspot caves and groundwater habitats.

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 of the obligate subterranean dwelling fauna in multiple hierarchical levels. We focused on three interrelated questions-(1) what is the spatial pattern of epikarst species diversity; (2) how does species diversity partition between local, and regional components (nested and replacement); and (3) whether epikarst hotspots are subterranean hotspots in general. We analyzed the geographic pattern of species richness of 30 species of obligate subterranean copepods found in 81 drips in Slovenian caves in three karst regions-Alpine, Dinaric, and Isolated. Comparison of Chao1 and observed (Mao-tau) estimates of species richness indicated sampling in most drips was complete, but species accumulation curves indicated roughly half of the sites in the Dinaric karst had not reached an asymptote. Overall, within drip diversity accounted for three species, different drips in a cave another three, different caves in a region six species, and different regions accounted for the remaining 18 species. Sites in the Dinaric karst had much higher species richness than the other sites, which is in agreement with studies of other components of the subterranean fauna. The fauna associated with drips in Županova jama (jama = cave), in the east-central Dinaric karst was the richest found. While turnover explained the majority of β-diversity, nestedness in the form of hotspot drips was important as well. A consequence is that a small number of drips largely determine cave and regional species diversity.

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 phrase) are the subterranean habitats. We have a relatively rich vocabulary to describe habitats (e.g., MSS, epikarst, hypotelminorheic) and to describe the closeness of association of a particular species or population with these habitats (e.g. trogloxene, troglophile, and troglobiont). Trajano provides a bridging principle between the ecological theater and the evolutionary play with the concept of source and sink populations. What has been given much less attention is the morphological side, coined by Christiansen, that is the results of the evolutionary play. The word we have available is “troglomorphy”, which has been taken to mean loss of eyes and pigment, loss of eyes and pigment as well as increases in extra-optic sensory structures, any convergent change in any subterranean population. loss of eyes and pigment, loss of eyes and pigment as well as increases in extra-optic sensory structures, any convergent change in any subterranean population. Only regressive changes are included in the first meaning; both regressive and progressive changes are included in the second; and the third includes autamorphy as well as homoplasy. Typically, it is used for the suite of characters involved, rather than an individual character. We suggest that the term “troglomorphy” be restricted to convergent changes (in the sense of [2] above) in subterranean habitats, and that the phrase “cave-dependent”, also used by Christiansen, be used when considering only caves, and perhaps be joined by phrases such as “MSS-dependent”. Additionally, the phrases ‘cave-dependent”, “MSS-dependent”, etc. be used for individual characters.

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 richness for groundwater crustaceans, indicating that tropics are not hotspots of species richness. Detailed analyses of subterranean biodiversity patterns in Europe show that species richness peaks in regions of mid-latitude, where the beneficial effects of a high productive energy and high habitat heterogeneity have not been counteracted by cold or arid historical events. The range size of European groundwater crustacean species increases northward, a pattern which is best explained by long-term climatic changes. Subterranean species have narrow distribution ranges, which results in a high spatial turnover in species composition across regions and a disproportionally high contribution of regional diversity to total species richness. Within regions, biodiversity patterns are diverse, and their explanations vary across regions, but hotspots contribute only a small proportion of the regional species pool. Molecular approaches to biodiversity studies offer promising research avenues for further documenting and understanding subterranean biodiversity patterns.

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 terrestrial cave communities are transitory organic matter brought in by bats and cave crickets, and riparian deposits along streams. A total of 40 troglobionts are known, 19 of which are endemic to the Greenbrier karst. The highest species richness is in the contact caves and Buckeye Creek drainage in Greenbrier County. Greenbrier County is a hotspot of troglobionts in the USA.

Seed dispersal by ants was studied in three populations of the myrmecochore, Sanguinaria canadensis, located in three habitats, each of which showed a different level of disturbance. Frequency of seed removal and the distances seeds were carried by ants were related to plant density, dispersion and the relative proportions of sexual and asexual reproduction in each population. Seeds in the least disturbed habitat were removed frequently and carried, by a wide variety of ants, distances of up to 12 m. Plant density was low and clone size was small. There was a relatively low level of sexual (seed) reproduction but seeds were generally transported well beyond the boundaries of the parent clones. By contrast, at the most disturbed site, plant density was high and clone size was very large. While there was a high level of seed production, seeds were rarely moved by ants and since removal distances were short, the probability of a seed being relocated beyond the limits of the parent clone was miniscule. The third population from a habitat which was intermediate in disturbance yielded data intermediate to the others. The data show that habitat disturbance, in disrupting the ant fauna and hence the ant-seed mutualism, has profound effects upon population density, dispersion and patterns of reproduction. Density-dependent regulation of sexual output predicted, for example, by the Strawberry-Coral model (Williams 1975), is maladaptive when the antseed mutualism is disturbed. We discuss the implications of this for theoretical modeling, the significance of mutualisms and the assessment of disturbance for conservation.

The first cave-limited species found in Mammoth Cave was described in 1842 by DeKay. By 1888, 19 stygobionts and troglobionts were known. At present, there are 32 described troglobionts (terrestrial obligate cave dwellers) and 16 stygobionts (aquatic obligate cave dwellers) from Mammoth Cave. It is the third richest cave worldwide in terms of terrestrial species. Globally, the aquatic species richness is unremarkable, but it is one of the most diverse aquatic caves in the USA. Possible reasons for the high terrestrial species richness include high levels of available organic matter, a unique geographic position at the intersection of several major cave fauna regions, and its immense size. In comparison with Vjetrenica, a global hot spot of terrestrial species richness in Bosnia and Herzegovina, taxonomic diversity in Mammoth Cave is similar, although Vjetrenica has more families of beetles.

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 habitats, taking advantage of the higher food resources available and modulating their distribution by photophobic behavior. We argue that the upper boundary is an interesting system in the study of classic ecological and evolutionary questions. The lower boundary of the distribution of groundwater species (approximately 2000–4000 meters) is likely controlled by physicochemical parameters, including temperature, pressure, and oxygen. The lower boundary warrants further research, and it is one of the most poorly explored areas of the biosphere.

Epikarst is not only an important component of the hydrogeology of karst and an active site of speleogenesis, it is habitat for a number of species adapted to subterranean life. Water in epikarst, with a residence time of days to months, is a highly heterogeneous habitat, and the animals are primarily sampled from continuously sampling dripping water or collecting from residual drip pools. While the subterranean fauna of cracks and crevices has been known for over 100 years, it is only in the past several decades that epikarst has been recognized as a distinct habitat, with reproducing populations of stygobionts. Dissolved organic carbon in epikarst drip water is a primary and sometimes the only source of organic matter for underlying caves, especially if there are not sinking streams that enter the cave. Typical concentrations of organic carbon are 1 mg L -1 . The fauna of epikarst is dominated by copepods, but other groups, including some terrestrial taxa, are important in some areas. Most of the diversity is β-diversity (between drips and between caves). In Slovenia, an average of nearly 9 stygobiotic copepod species were found per cave. In studies in Romania and Slovenia, a number of factors have been found to be important in determining species distribution, including ceiling thickness, habitat connectivity and habitat size. In addition to eye and pigment loss, epikarst copepod species may show a number of specialization for life in epikarst, including adaptations to avoid displacement by water flow. Several geoscientists and biologists have challenged the uniqueness and importance of epikarst, but on balance the concept is valid and useful. Fruitful future research directions include development of better sampling techniques, studies to explain differences among nearby epikarst communities, phylogeographic studies, and assessing the possible role of copepods as tracers of vadose water. adaptation; cave ecology; Copepoda; stygobionts; subterranean biodiversity

A series of potential pitfalls (fallacies) in estimating subterranean biodiversity are outlined: (1) provincialism—treating different regions differently, especially with respect to new discoveries and undescribed species; (2) equality of described and undescribed species—ignoring the possibility that undescribed species are not really new species; (3) isotropy—assuming all cave regions of similar size have equally rich faunas; (4) scale invariance—ignoring the affect of area on species richness; and (5) misuse of expert opinion—the over-reliance on experts estimates often without comparable estimates for all areas. Some standard procedures are suggested for subterranean biodiversity studies, and the value of such studies is emphasized.

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 species distribution and description, but important conceptual and synthetic papers have also appeared. Two special issues were devoted to interdisciplinary topics with a major biological component-time in karst, and carbon and boundaries in karst. Key words: biospeleology, cave biology, Egon Pretner, speleobiology.

Leta 1999 sva opisala 20 jam in kraskih vodnjakov, v katerih živi po 20 ali vec na podzemlje vezanih vrst živali. Pet izmed teh jam je ali pa je bilo urejenih za turisticno izrabo: Postojnsko-planinski jamski sistem (Slovenija), Sistem Baget - Sainte Catherine (Francija), Shelta Cave (Alabama, ZDA), Mammoth Cave (Kentucky, ZDA) in Vjetrenica (Bosna in Hercegovina). Prav dejstvo, da imajo lahko mocno preurejene jame z visokim stevilom obiskovalcev tudi pestro favno, kaže, da se oboje ne izkljucuje. Stevilne standardne tehnike za vzorcevanje, so uporabne le v malostevilnih jamah. Te metode so le omejeno uporabne. Onesnaženje je lahko za jamske živali neposredno pogubno ali pa omogoca povrsinskim živalim, da tudi v podzemlju izpodrivajo. Zato moramo zasledovati tako gostoto favne, kot tudi spremembe v njeni taksonomski sestavi. Ob nacrtovanju novih posegov je treba pred kakrsnim koli urejanjem raziskati krajevno favno, tako povrsinsko kot podzemeljsko. Za biolosko zasledovanje stanja priporocava naslednje: 1. vzorcenje skozi daljse obdobje; 2. nastavljanje vab v kopenskih in v vodnih habitatih; 3. nastavljanje loncastih pasti v kopenskih habitatih. In 1999, we described the twenty caves and karst wells that have 20 or more species of obligate cave organisms living in them. Among these caves five are developed as tourist caves — Postojna-Planina Cave System (Slovenia), Baget - Sainte Catherine System (France), Shelta Cave (Alabama, USA), Mammoth Cave (Kentucky, USA), and Vjetrenica Cave (Bosnia & Herzegovina). For these and other tourist caves, there is a special responsibility to protect this fauna. The very fact that caves with large numbers of visitors and with modifications to the cave can have high species diversity shows that the two are not incompatible. Many of the standard sampling techniques, may work in some caves only; they are of restricted use. Pollution may be either directly detrimental to the cave fauna or may enable surface species to outcompete the endemic cave fauna. Therefore, changes in the quantity of fauna have to be monitored as well as changes in its taxonomic composition. In the case of new tourist installations, the local cave and surface fauna has to be investigated prior to any modifications. For biological monitoring, we recommend one of the following: 1. minimum-time census, rather than minimum-area census; 2. baiting in both terrestrial and aquatic habitats; 3. pitfall traps (baited or unbaited) in terrestrial habitats.

The unique morphology of cave animals has interested biologists at least since the time of Lamarck. After a number of non-adaptive explanations for the morphology of cave animals, especially with respect to eye and pigment loss, a neo-Darwinian explanation, emphasizing constructive morphological changes rather than losses, was put forward by Barr, Christiansen, and Poulson in the 1960’s. Emphasizing convergent evolution (troglomorphy), this paradigm has recently been challenged, with evidence of divergent selection and the widespread occurrence of morphologically similar species in other subterranean habitats, including ones with abundant food and relatively strong environmental fluctuations. An emerging paradigm emphasizes the central role of darkness in convergent evolution, and the role of habitat size and interspecific competition in divergent evolution of subterranean species. Sprememba paradigme o evoluciji jamskega življenja Edinstvena morfologija jamskih živali, predvsem v povezavi z izgubo oci in pigmenta, je zanimala biologe že od casa Lamarcka. Kasneje so bile predstavljene tudi druge, t.im. neodarvinisticne razlage, s poudarkom na konstruktivnih morfoloskih spremembah namesto izgubah, povzete s strani Barra, Christiansena in Poulsona v 60. letih 20. stoletja. Z novejsimi raziskavami o divergentni selekciji in razsirjeni prisotnosti morfolosko podobnih vrst v drugih podzemeljskih habitatih, vkljucno s tistimi, kjer je veliko hrane in z relativno velikimi okoljskimi nihanji, se je zamajala paradigma, temeljeca na konvergentni evoluciji (troglomorfija). Novo nastajajoca paradigma poudarja osrednjo vlogo teme v konvergentni evoluciji, ter vlogo velikosti habitata in medvrstne kompeticije v divergentni evoluciji podzemeljskih vrst.

A number of shallow groundwater habitats that occur in the Coastal Plain and Piedmont of the mid-Atlantic region are documented and described. These isolated tiny aquifers are underlain by clay (hypotelminorheic habitats) and exit at seepage springs, springs, tiled fields and tile drains, and shallow wells. These shallow groundwater habitats harbor species with reduced eyes and pigment that are limited to these habitats. The distribution of 23 such species—four planarians (Sphalloplana and Phagocata), one snail (Fontigens), 13 amphipods (Stygobromus), and five isopods (Caecidotea)—is documented, based on over 450 records. More species (16) were found in hypotelminorheic habitats than in other shallow groundwater habitats. Also, more species were found exclusively in either the Piedmont or Coastal Plain, but seven species were found along the boundary (Fall Line) between these physiographic provinces. Compared to surface waters in nearby habitats, hypotelminorheic water had higher conductivity, higher dissolved oxygen, and slightly lower pH.

Caves are the best known subterranean habitats, harbouring animals with a convergent morphology of reduced eyes and pigment and elongated appendages (troglomorphy). We have identified a group of aphotic aquatic habitats close to the surface [shallow subterranean habitats (SSHs)] that also harbour troglomorphic species, but with intimate surface connections, typically small in size but very abundant, with high levels of organic matter compared to caves. SSHs are hypotelminorheic, hyporheic, and epikarstic habitats. All SSHs show a pattern of environmental variation intermediate between that of surface and deep subterranean habitats, and all show seasonal and sometimes daily fluctuations in temperature but with truncated extremes. Initial colonization of these habitats was likely the result of environmental changes, especially increasing aridity, perhaps during the Pleistocene and the Messinian salinity crisis. The evolution of the troglomorphic morphology of reduced eyes and pigment and elaborated extra-sensory structures likely occurred in situ rather than by dispersal from other habitats. SSHs may be a stepping stone to colonization of deeper subterranean habitats. Copyright © 2011 John Wiley & Sons, Ltd.

1. Aquatic subterranean species are often geographically and numerically scarce. Many of these species are denizens of epikarst, the uppermost zone of karst with semi-isolated solutional openings and channels, and are only known from drip pools in caves where they accumulate as a result of animals dripping out of the epikarst. 2. The question of whether these pool communities adequately reflected the epikarst community was addressed by directly collecting animals from drips in a continuous collecting device. 3. The study area was six caves in Slovenia, where a total of 35 drips and associated pools were sampled for copepods for a period of approximately one year. A total of 37 copepod species were found, 25 of them stygobionts and 16 epikarst specialists. 4. Overall, the frequency of stygobionts was 1.5 times higher in drips compared with pools and the frequency of epikarst specialists was three times higher in drips compared with pools, and the frequency of immature individuals was higher in drips compared with pools, with the exception of one artificially enlarged pool in Skocjanske jame. The cause of this difference is probably increased juvenile mortality in pools and reduced reproduction, indicating that pools are not source populations. 5. The results of this research suggest that epikarst per se, not just the sampling sites (including pools) in caves, needs to be the focus of conservation planning. Copyright © 2010 John Wiley & Sons, Ltd.

We investigated the pattern of species richness of obligate subterranean (troglobiotic) beetles in caves in the northwestern Balkans, given unequal and biased sampling. On the regional scale, we modeled the relationship between species numbers and sampling intensity using an asymptotic Clench (Michaelis-Menten) function. On the local scale, we calculated Chao 2 species richness estimates for 20 9 20 km grid cells, and investigated the distribution of uniques, species found in only one cave within the grid cell. Cells having high positive residuals, those with above average species richness than expected according to the Clench function, can be considered true hotspots. They were nearly identical to the observed areas of highest species richness. As sampling intensity in a grid cell increases the expected number of uniques decreases for any fixed number of species in the grid cell. High positive residuals show above average species richness for a certain level of sampling intensity within a cell, so further sampling has the most potential for additional species. In some cells this was supported by high numbers of uniques, also indicating insufficient sampling. Cells with low negative residuals have fewer species than

The spatial and temporal patterns in concentration and character of dissolved organic matter (DOM) in karst basins in Slovenia and the United States were characterized. DOM in the shallow aquifer, or epikarst, waters was characterized by low, stable concentration and compounds of low aromaticity and humification. There was strong temporal coherence in DOM character, but not concentration, across locations within the epikarst. DOM in sinking streams, cave streams, and resurgence springs typically had higher DOM concentration and aromaticity. Fluorescence and parallel factor analysis of DOM revealed that humic or fulvic-like substances in soils, surface and cave streams, and springs were the dominant fluorophores. However, DOM extracted from soils was chemically different from that present in the stream and spring waters. Epikarst water contained humic-like and protein-like DOM, and had fluorescence characteristics indicative of microbial uptake and release of DOM in the epikarst. These data show that there are substantial basin-scale patterns in DOM concentration and character and that aquifer structure influences the spatial patterns of DOM in karst groundwater.

Shallow (superficial) subterranean habitats, or SSHs are very close to the surface, but are aphotic. Some of these habitats are large cavities, especially lava tubes, while others are small cavity habitats, especially the underflow of streams and rivers (interstitial aquifers), and the soil. But, there is an especially interesting set of SSHs that do not fit into either category, with intermediate sized space with many close connections with the surface. These habitats include talus and scree slopes, milieu souterrain superficiel (MSS), in both carbonate (soluble) and non-carbonate rocks, including volcanic rocks. Epikarst, the uppermost layer of karst formed largely by solutional processes that may be air or water filled, occupies a similar vertical position to that of the MSS, but perhaps with smaller spaces. The most superficial of SSHs are the miniature perched aquifers (isolated wetlands) given the name hypotelminorheic that exit through seepage springs, diffuse discharges when the flow cannot be immediately observed but the land surface is wet compared to the surrounding area. These two SSHs (epikarst and hypotelminorheic), which do not extend beyond a few meters in depth are called strict sense shallow subterranean habitats and will be presented in more detail.

The amphipod genus Stygobromus occurs in a variety of subterranean habitats in North America, including caves, phreatic (groundwater) lakes, and superficial subterranean habitats (seeps and epikarst). The habitats share the absence of light but differ in other features, such as pore size of the habitat, available food, and degree of seasonality. Measurements of body size, antennal size, and antennal segment number of type specimens were compared for 56 species occurring in the eastern United States. Except for differences in body size, differences among species in the four different habitats were not significant. Body size was related to relative pore size of the habitat, e.g., epikarst, with the smallest spaces, had the smallest species. However, in all habitats, there was one very large species (> 15mm); these enigmatic species apparently occupy a distinct ecological niche, perhaps being more predatory. Differences in relative antennal size showed no significant differences among habitats, and ...

Summary 1. The causes of distribution patterns of stygobionts (obligate subterranean-dwelling aquatic species) were examined with special emphasis on vicariance and dispersal. 2. Dispersal was investigated on the premise that if migration is important, then migration at small scales should predict patterns at larger scales. Data on the copepod fauna of epikarst in Slovenia were especially useful for the study of migration, because data on habitat occupancy could be collected at scales of individual drips located metres apart to the scale of individual caves to entire karst regions. Occupancy of drips in one cave was a remarkably good predictor of occupancy of caves in a region, although not of the overall range of a given species. These results were also supported by occupancy patterns of the general stygobiotic fauna of West Virginia caves, compared at different scales. 3. Vicariance was investigated by noting that proximity to marine embayments increases the likelihood of vicariant speciation. In the U.S.A., only the fauna of the Edwards Aquifer of Texas has a significant component of marine-derived species. Differences in shape of the relationship between species number and number of caves in a county indicated that the marine-derived component represented an addition to rather than a replacement of the other stygobiotic species. 4. Thus, we found evidence for the importance of both vicariance and dispersal. The techniques employed could be used to study these patterns more generally, as more data become available.

Summary 1. This paper is an introduction to and overview of a special issue on groundwater ecology with a focus on biodiversity assessment and conservation. The subterranean environment harbours unique biological communities of remarkable diversity, comprising both microorganisms and micro-, meio- and macrofauna. This biodiversity of ground waters remains poorly known compared to that of freshwater surface habitats. 2. The papers in this special issue summarise the outcome of a large-scale European survey, the PASCALIS project (Protocol for the ASsessment and Conservation of Aquatic Life In the Subsurface), complemented by results from a few other comprehensive studies on groundwater diversity. The papers fall into five broad groups. The first group reviews the biology and ecology of poorly investigated but important subterranean taxa such as Bacteria and Archaea, Oligochaeta and Copepoda. Five papers deal with groundwater biodiversity patterns in the six selected PASCALIS regions. Issues addressed range from broad-scale diversity patterns to partitioning of species richness, cryptic diversity, sampling methodology, and the use of surrogate taxonomic groups for assessing overall diversity. Four papers analyse biodiversity patterns in single European regions, the French Jura, the Walloon region of Belgium, the Lessinian Mountains of Italy and south-western Germany. Two additional papers address the issue of site selection for the conservation and protection of groundwater species, and the fifth group of three papers expands two central PASCALIS themes – sampling adequacy and the role of dispersal. Finally, a concluding synthesis paper summarises advances in understanding groundwater biodiversity patters and conservation and points out important challenges for future research. 3. Collectively, the information presented in this special issue represents the first broad-scale examination of aquatic subterranean diversity based on a rigorously standardised sampling protocol, the first examination of stygofauna patterns in both karstic and non-karstic aquifers, a first step toward integrating traditional and molecular taxonomic studies of groundwater biodiversity, and a start toward elaborating strategies for groundwater reserve selection.

Summary 1. This paper is a synthesis of a special issue on groundwater biodiversity with a focus on obligate subterranean species, the stygobionts. The series of papers constitutes a great leap forward in assessing and understanding biodiversity patterns because of the use of large quantitative data sets obtained over a broad geographic scale. They also represent a conceptual shift, away from a purely taxonomic and phylogenetic focus to the analysis of whole groundwater assemblages. 2. The general patterns emerging for groundwater fauna are: very high levels of endemism, low local diversity relative to regional diversity, a limited number of lineages, occurrence of many relicts, and truncated food webs with very few predators. 3. β-Diversity is at least as important as α-diversity in determining total richness at different scales (aquifer, basin and region) and overall taxa richness increases across spatial scales. 4. Advances in understanding groundwater biodiversity patterns further include identification of several important factors related to geology and hydrology that determine the composition of European stygobiotic assemblages. 5. Important challenges for future research include improving sampling strategies, filling gaps in sampling coverage, intensifying research on theoretical and statistical models, and including functional and genetic diversity components in biodiversity assessments. 6. Strategies are proposed for protecting groundwater biodiversity and an argument is made to integrate biodiversity in groundwater management. Applying principles such as complementarity and flexibility for groundwater biodiversity conservation is a major step toward delineating a reserve network that maximise species representation at the European scale.