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Abstract 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 and June 2022 using five trap types. We sampled 108,005 individuals, 1,054 morphospecies, and seven phyla, globally the largest dataset on MSS in IF. Arthropoda represented 97% of all invertebrates sampled. We identified 31 troglomorphic organisms, primarily Arthropoda and Platyhelminthes. MSS traps were the most efficient method, capturing 80% of all invertebrates. Morphospecies were more prevalent in each locality than shared among localities. Species replacement was the main processes to spatial differences. Over time, we found a decrease of total dissimilarity and importance of species replacement for troglomorphic organisms. A positive correlation between spatial distance and compositional dissimilarity of invertebrates was found. Iron Quadrangle and Southern Espinhaço Range showed marked differences in the spatiotemporal patterns of subterranean fauna. Brazilian IF are threatened, with their biological significance not fully understood but highly endangered due their limited distribution. Conservation efforts require a comprehensive understanding of both biotic and abiotic factors shaping the entire IF ecosystem.

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. anacostensis sp. nov. is a member of the S. tenuis species group but differs from related congeners based on body size, serrate blade-like edge of both palms of gnathopods 1 and 2, presence of rastellate setae on the posterodistal margin of the carpus of gnathopod 2, and aspects of the second antennae, mandibular palp, pereopods 5–7, uropods 1 and 2, and telson. Moreover, S. anacostensis sp. nov. is genetically distinct from S. tenuis in the Washington D.C. metropolitan area. The description of S. anacostensis sp. nov. increases the number of described Stygobromus species to eight in the Washington D.C. area and highlights the need for continued biodiversity studies, even in regions that have received considerable attention.

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, but as a discipline it has not fully developed. Speleobiology emphasizes the connection with biology, especially ecology and evolutionary biology. Biospeleology can be construed as the taxonomic and distributional aspects of the biology of caves while speleobiology can be construed as the aspects pertaining to general biological principles such as evolution.

Twelve seepage springs in a 3 km2 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 and 1 exinction. Three populations persisted. These results are consistent with the proposed metapopulation hypothesis of population structure.

Since the 1980s, with the widespread use of the phrase biodiversity [...]

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 most modern form is the accumulation of selectively neutral, structurally reducing mutations. Selectionist explanations include direct selection, often involving metabolic efficiency in resource poor subterranean environments, and pleiotropy, where genes affecting eyes and pigment have other effects, such as increasing extra-optic sensory structures. This dichotomy echoes the debate in evolutionary biology in general about the sufficiency of natural selection as an explanation of evolution, e.g., Kimura’s neutral mutation theory. Tests of the two hypotheses have largely been one-sided, with data supporting that one or the other processes is occurring. While these tests have utilized a variety of subterranean organisms, the Mexican cavefish, Astyanax mexicanus, which has eyed extant ancestral-like surface fish conspecifics, is easily bred in the lab, and whose whole genome has been sequenced, is the favored experimental organism. However, with few exceptions, tests for selection versus neutral mutations contain limitations or flaws. Notably, these tests are often one sided, testing for the presence of one or the other process. In fact, it is most likely that both processes occur and make a significant contribution to the two most studied traits in cave evolution: eye and pigment reduction. Furthermore, narrow focus on neutral mutation hypothesis versus selection to explain cave-evolved traits often fails, at least in the simplest forms of these hypotheses, to account for aspects that are likely essential for understanding cave evolution: migration or epigenetic effects. Further, epigenetic effects and phenotypic plasticity have been demonstrated to play an important role in cave evolution in recent studies. Phenotypic plasticity does not by itself result in genetic change of course, but plasticity can reveal cryptic genetic variation which then selection can act on. These processes may result in a radical change in our thinking about evolution of subterranean life, especially the speed with which it may occur. Thus, perhaps it is better to ask what role the interaction of genes and environment plays, in addition to natural selection and neutral mutation.

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 published monographs with the data from our own recent field surveys. Further, as they are connected via water channels or small crevices in bedrock, we defined the Vjetrenica Cave System as a system comprising Vjetrenica and Bjelušica Caves and Lukavac Spring. Altogether, 93 troglobiotic, i.e., obligate subterranean aquatic (48) and terrestrial (45), taxa were reported for the system, verifying the Vjetrenica Cave System as the second richest locality in subterranean biodiversity in the world. The global uniqueness of the system is also reflected in the fact that as many as 40 troglobiotic species were described from the system. Finally, we reviewed the factors endangering this unique subterranean community and questioned whether it will withstand human-induced changes and pressures due to infrastructural development in southern Bosnia and Herzegovina.

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

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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 Crangonyx shoemakeri, a wetland species, and Stygobromus tenuis, a subterranean species, burrowed in clay in the laboratory after surface water was removed. Gammarus minus, a spring species, did not. All three species exhibited behavioral changes as the habitat dried out.

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.

Kenneth A. Christianse, speleobiologist and collembologist, died at the age of 93.

Riding a wave of interest in biodiversity patterns in surface-dwelling communities, in 2000, Culver and Sket [...]

Caves are the best studied aquatic subterranean habitat, but there is a wide variety of these habitats, ranging in depth below the surface and size of the spaces (pore or habitat size). Both factors are important in setting limits to species composition and richness. In addition to caves, among the most important shallow aquatic subterranean habitats are the hyporheal (underflow of rivers and streams), the hypotelminorheal (very superficial drainages with water exiting in seeps), epikarst, and calcrete aquifers. Although it is little studied, both body size and species composition in the different habitats is different. Because of high levels of endemism and difficulty in access, no subterranean habitats are well sampled, even caves. However, there are enough data for robust generalizations about some geographic patterns. Individual hotspot caves are concentrated in the Dinaric region of southern Europe, and overall, tropical regions have fewer obligate aquatic cave dwellers (stygobionts). In all subterranean aquatic habitats, regional diversity is much higher than local diversity, but local diversity (especially single cave diversity) may be a useful predictor of regional species richness. In Europe there is a ridge of high aquatic subterranean species richness basically extending east from the French–Spanish border. Its cause may be either high productivity or that long-term temperature oscillations are at a minimum. With increased collecting and analysis, global and continental trends should become clearer.

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 epikarst copepods from drips in six Slovenian caves and 12 physico-chemical factors (temperature, conductivity, pH, Ca2+, Na+, K+, Mg2+, NH4+, and Cl−, NO2−, NO3−, and SO42−) was explored. Statistical analyses included principal components analysis, logistic mixed models, stepwise logistic multivariate regression, classification trees, and random forests. Parametric statistical analyses demonstrated the overall importance of two variables—temperature and conductivity. The more flexible statistical approaches, namely categorical trees and random forests, indicate that temperature and concentrations of Ca2+ and Mg2+ were important. This may be because they are essential nutrients or, at least in the case of Ca2+, its importance in molting. The correlation of Cl− and NO3− with copepod abundance may be due to unmeasured variables that vary at the scale of individual cave, but in any case, the values have an anthropogenic component. This contrasts with factors important in individual species’ niche separation, which overlap with the community parameters only for NO3−.

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.

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 specializations 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.

Leta 1999 sva opisala 20 jam in kraških vodnjakov, v katerih živi po 20 ali več na podzemlje vezanih vrst živali. Pet izmed teh jam je ali pa je bilo urejenih za turistično 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 močno preurejene jame z visokim številom obiskovalcev tudi pestro favno, kaže, da se oboje ne izključuje. Številne standardne tehnike za vzorčevanje, so uporabne le v maloštevilnih jamah. Te metode so le omejeno uporabne. Onesnaženje je lahko za jamske živali neposredno pogubno ali pa omogoča površinskim živalim, da tudi v podzemlju izpodrivajo. Zato moramo zasledovati tako gostoto favne, kot tudi spremembe v njeni taksonomski sestavi. Ob načrtovanju novih posegov je treba pred kakršnim koli urejanjem raziskati krajevno favno, tako površinsko kot podzemeljsko. Za biološko zasledovanje stanja priporočava naslednje: 1. vzorčenje skozi daljše obdobje; 2. nastavljanje vab v kopenskih in v vodnih habitatih; 3. nastavljanje lončastih 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.

http://dx.doi.org/10.3986/ac.v42i2-3.657 From January 7 to January 11, 2013, the Karst Waters Institute (KWI) and the National Cave and Karst Research Institute (NCRKI) held an international and multidisciplinary symposium on Carbon and Boundaries in Karst at NCKRI headquarters in Carlsbad, New Mexico.There is growing interest in the dynamics of both inorganic and organic carbon in karst systems, and especially in the flux of carbon and nutrients between the surface and subsurface, and between different components (e.g. epikarst and vadose zone) in the karst subsurface. This symposium was about these and other questions connected to carbon in karst and boundaries in karst. It was especially timely both because of rapid advances in the field and the importance of carbon sequestration in global climate change The symposium highlighted recent advances in biology, geology, and hydrology that are helping us understand the dynamics of karst ecosystems, especially with respect to carbon. The talks were organized around seven main themes: • The Upper Boundary – Epikarst • The Lower Boundary – Phreatic Zone • Lateral Inputs — Insurgences • Lateral Outputs — Resurgences • CO2 — Processing and Storage • Organic Carbon — Sources and Quality • Synthesis and Large Scale Models Sixty participants from seven countries attended the week-long meeting which included an excursion to Carlsbad Caverns National Park. For the first time at a KWI meeting, several participants, who were unable to attend in person, gave their presentations via Skype. The meeting was highlighted by two keynote presentations: • Groundwater Ecology of Alluvial River Flood Plains, Jack Stanford, Flathead Lake Biological Station, Polson, Montana • Karst – Conduit Matrix Exchange and the Karst Hyporheic Zone, John Wilson, New Mexico Institute of Mining and Technoloogy, Socorro, New Mexico. Two most distinguished karst scientists, William B. White of Pennsylvania State University and Derek Ford of McMaster University jointly summed up the meeting. The following is a list of oral and poster presentations given at the meeting. Participants were invited to submit articles that elaborated their meeting presentations to Acta Carsologica. Penny J. Boston: Chemotrophy meets heterotrophy: the inverted 'critical zone' of the subsurface Kathleen Brannen, Annette Engel, and Ross Larson: Microbial controls on in situ production of dissolved organic matter Amy L. Brown, Jonathan B. Martin, Elizabeth Screaton, John Ezell, James Sutton and Patricia Spellman:Redox state in karst aquifers: Impacts of DOC- and DO-rich river water intrusion into Floridan aquifer springs Terri Brown, Susan M. Pfiffner, and Annette S. Engel: Component isolation and lipid profiling to characterize dissolved organic matter transformations along a groundwater flow path Sarah K. Carmichael, Mary J. Carmichael, Amanda Strom, Krissy W. Johnson, Leigh Anne Roble, Yongli Gao, Cara M. Santelli, and Suzanna L. Bräuer: Using biominerals to assess anthropogenic inpact: a case study in Carter Salt Peter Cave, CarterCounty, TN Matthew D. Covington: A simple theoretical framework to interpret spring variations and constrain mechanistic models of karst processes David C. Culver and Tanja Pipan: Convergence and Divergence in Caves and Shallow Subterranean Habitats Annette Summers Engel: Microbial activities at geochemical interfaces in cave and karst environments Cene Fišer: Interactions between surface and subterranean amphipods in springs Lee J. Florea: Preliminary carbon sequestration and denudation rates within the karst of the Cumberland Plateau, USA Daniel W. Fong, Christopher Seabolt, and Kaitlin C. Esson: Determinants of macroinvertebrate diversity in karst springs of the Mid-Atlantic region, USA Derek Ford: Bicarbonate water chemistry of Little Limestone Lake, a beautiful marl lake in Manitoba, Canada Franci Gabrovšek: The relative importance of speleogenetic phases as revealed by numerical models Christian Griebler: Dynamics and limitations of organic carbon turnover in porous aquifers Jonathan S. Harding and Troy Watson: The longitudinal response of benthic invertebrate communities to caves Katrina K. Henry, Kenneth A. Salaz, and John L. Wilson: Experimental design and instrumentation to observe karst conduit hyporhiec flow Janet S. Herman, Alexandria G. Hounshell, Rima B. Franklin, and Aaron L. Mills: Biological control on acid generation at the conduit-bedrock boundary in submerged caves Benjamin T. Hutchins*, Benjamin F. Schwartz, and Annette S. Engel: Environmental controls on organic matter production and transport across surface- subsurface and geochemical boundaries in the Edwards Aquifer, Texas, USA Daniel S. Jones, Irene Schaperdoth, and Jennifer L. Macalady: Subaerial microbial life in the sulfidic Frasassi Cave System, Italy William K. Jones: Physical Structure of the epikarst James E. Kaufmann and Jeffery Crews: Stratigraphic control on conduit development in the Ozark Karst, Missouri, USA Katherine J. Knierim, Erik Pollock, and Phillip D. Hays: Using isotopes of dissolved inorganic carbon species and water to separate sources of recharge in a cave spring, northwestern Arkansas Andrew J. Kowalczk: Quantitatively modeling source influences on cave air carbon dioxide chemistry Erik B. Larson and John E. Mylroie: Quaternary glacial cycles: karst processes and the global CO2 budget Jonathan B. Martin, Mitra Khadka, Marie Kurz, John Ezell, Amy Brown: Karst in the global carbon cycle Ioana N. Meleg: Spatio-temporal trends in diversity of subsurface assemblages from the vadose zone of the Carpathian karst in Romania Aaron L. Mills, Janet S. Herman, and Terrence N. Tysall: Comparison of water quality in submerged caves with that of diffuse groundwater immediately proximal to the conduit Diana E. Northu*, Noelle G. Martínez, Lory O. Henderson and Elizabeth T. Montano: Carbon cycling in arid land caves: implications for microbial processes Pedro Oromí and Heriberto D. López: Shallow Subterranean Habitats in Volcanic Terrain Randall L. Paylor* and Carol M. Wicks: Particulate inorganic carbon flux in karst and its significance to karst development and the carbon cycle Tanja Pipan and David C. Culver: Patterns of organic carbon in shallow subterranean habitats (SSHs) Junbing Pu*, Daoxian Yuan, Licheng Shen and Heping Zha: Seasonal, diurnal and storm-scale PCO2 variations of cave stream in subtropical karst area, Chongqing, SW China Nataša Ravbar: Variability of groundwater flow and transport processes in karst under different hydrologic conditionsWhere’s the fire? Sam Rochelle, Michael N. Spilde, and Penny J. Boston: An analysis of carbon precipitates in Black and other caves of the Upper Guadalupe Mountains, New Mexico Benjamin F. Schwartz*, Susanne Schwinning, Brett Gerard, Kelly R. Kukowski, Chasity L. Stinson, and Heather C. Dammeye: Using hydrogeochemical and ecohydrologic responses to understand epikarst processes in semi-arid systems, Edwards Plateau, Texas, USA Kevin S. Simon: Carbon flux in the Dorvan-Cleyzieu karst: lessons from the past to guide future research Jack A. Stanford: Groundwater ecology of alluvial river flood plains Philip van Beynen, Derek Ford and Henry Schwarcz: Seasonal influx of organic carbon into Marengo Cave, Indiana, USA Michael P Venarsky, Brock M Huntsman, Jonathan P Benstead, Alexander D Huryn: Testing carbon limitation of a cave stream ecosystem using a whole-reach detritus amendment George Veni:The role of karst conduit morphology, hydrology, and evolution in the transport, storage, and discharge of carbon and associated sediments William B. White: Carbon fluxes in karst aquifers: sources, sinks, and the effect of storm flows Carol Wicks: Hydrograph interpretation − changes in time John L. Wilson: Karst conduit-matrix exchange and the karst hyporheic zone Yuan Daoxian: The role of geological processes in global carbon cycle: a review Zhang Qjang: The stability of carbon sink effect related to carbonate rock dissolution: a case study of the Caohai Lake geological carbon sink

subterranean habitatsOrganic carbon is likely to be a limiting factor in shallow subterranean habitats (SSHs). Data on dissolved organic carbon (DOC) in three SSHs are reviewed: (1) hypotelminorheic and associated seepage springs (Nanos Mountain, Slovenia), (2) hyporheic zones (Rhône River, France and seepage streams on Nanos Mountain, Slovenia), and (3) epikarst (China, Slovenia, and USA). Hypotelminorheic habitats are superficial groundwater sites less than 1 m below the surface that exit from seepage springs. Hyporheic habitats are the underflow of streams and rivers. Epikarst is the uppermost zone of karst with extensive small cavities and channels. Nanos hypotelminorheic sites that harbored stygobiotic species had organic carbon values averaging 3.4 mg C L−1, and temporal variability was high. For hypoheic sites in the Rhône River basin and on Nanos Mountain, mean values ranged from 1.4 to 3.5 mg C L−1. In the more extensively studied Rhône River basin sites, temporal variability was low. Epikarst DOC ranged from 0.70 to 1.10 mg C L−1 in three caves in China (Shihua Cave), Slovenia (Postojna Planina Cave System) and United States (Organ Cave, West Virginia). These results suggest that organic carbon in aquatic SSHs is lowest in epikarst. Keywords: dissolved organic carbon, epikarst, hyporheic, hypotelminorheic, seepage spring. DOI: 10.3986/ac.v42i2.603

Originally described by Meštrov in 1962, hypotelminorheic habitats are superficial subterranean drainages, typically less than a meter or so in depth, that emerge at small seepage springs. These are persistent wet spots, typically with blackened leaves in small depressions. There may be no flow during dry periods, but the underlying clay retains water above. They share the landscape with other small bodies of water (močila in Slovenian), not necessarily connected with groundwater. Hypotelminorheic habitats (mezišča in Slovenian) usually harbor a fauna dominated by species adapted to subterranean life, characteristically without eyes or pigment. The basic chemistry and hydrology of the habitat is described as are the basic faunal elements. The habitat is placed in a more general context by reviewing how species invade the habitat, their morphology, and their possible connection to deeper subterranean habitats.

Climate, and more generally the physical conditions in caves and other subterranean habitats have a profound influence on the biota. At longer time scale (centuries), climate change can force and/or isolate species in subterranean habitats. Not only Pleistocene climate changes, but earlier ones as well, suchas the Messinian salinity crisis were important in this regard. While many speleobiologists assume that caves are nearly constant environmentally and withscarce organic carbon, this is not the case, especially in non-cave subterranean habitats. Many shal­low subterranean habitats, suchas epikarst, seepage springs, and talus harbor highly modified organisms, ones without eyes and pigment and withelongated appendages. Yet these habi­tats are highly variable withrespect to temperature and other environmental factors, and often have highlevels of organic carbon. Overall, the role of these shallow subterranean habitats in the evolution and biogeography of subterranean species may be crucial. On smaller spatial scales, environmental differences, suchas differences in chemistry of epikarst water, may be im­portant in allowing large numbers of species to coexist.

Geographic distribution of stygobionts is often used to estimate age of a group by assuming vicariant speciation with little or no subsequent dispersal. We investigated the utility of using distributional data for Slovenian stygobiotic copepods by assuming that dispersal is a way to measure age of a species. We list some species of Copepoda that, on the basis of their range and frequency of occupancy within their range, should be older. Body size is not predictor either of range or frequency of occupancy.

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. Given the need for cave specialists to adapt to saturated humidity, presumably by cuticular thinning, the major stress of RH would be its deviation from saturation. RH in Río Secreto (Tuch) was invariant at three sites and displayed short deviations from 100% RH at the other four sites. These deviations were concentrated at the end of the nortes and beginning of the rainy season. Three of the sites in Sistema Muévelo Rico showed a similar pattern although the timing of the deviations from 100% RH was somewhat displaced. Four sites in Sistema Muévelo Rico were more variable, and were analyzed using a measure of amount of time of deviation from 100% RH for each 24 hour period. Strong seasonality was evident but, remarkably, periods of constant high humidity were not the same at all sites. In most Sistema Muévelo Rico sites, there was a detectable 24 hour cycle in RH, although it was quite weak in about half of them. For Río Secreto (Tuch) only one site showed any sign of a 24 hour cycle. The troglomorphic fauna was more or less uniformly spread throughout the caves and did not concentrate in any one area or set of RH conditions. Compared to temperature, RH is much more constant, perhaps even more constant than the amount of light. However, changes in RH as a result of global warming may have a major negative effect on the subterranean fauna.

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 Río Secreto (Tuch) 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 Río Secreto (Tuch) sites. While temperature variability is diminished relative to surface variation, its temporal pattern is worthy of further study.

Conference

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.

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.

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 local environmental conditions, such as cave humidity, or they could be associated with surface features that are surrogates for cave conditions. If surface features can be used to predict the distribution of important cave taxa, then conservation management is more easily obtained. We examined the hypothesis that the presence of major faunal groups of cave obligate species could be predicted based on features of the earth surface. Georeferenced records of cave obligate amphipods, crayfish, fish, isopods, beetles, millipedes, pseudoscorpions, spiders, and springtails within the area of Appalachian Landscape Conservation Cooperative in the eastern United States (Illinois to Virginia and New York to Alabama) were assigned to 20 x 20 km grid cells. Habitat suitability for these faunal groups was modeled using logistic regression with twenty predictor variables within each grid cell, such as percent karst, soil features, temperature, precipitation, and elevation. Models successfully predicted the presence of a group greater than 65% of the time (mean = 88%) for the presence of single grid cell endemics, and for all faunal groups except pseudoscorpions. The most common predictor variables were latitude, percent karst, and the standard deviation of the Topographic Position Index (TPI), a measure of landscape rugosity within each grid cell. The overall success of these models points to a number of important connections between the surface and cave environments, and some of these, especially soil features and topographic variability, suggest new research directions. These models should prove to be useful tools in predicting the presence of species in understudied areas.