Cave Microclimate Research Articles

Environmental and Human Impact on Ice Caves: The Example of the Wielka Śnieżna Cave in the Tatra Mountains (Poland)

Ice caves are characterised by specific microclimate, defined by the external climate as well as cave morphology (hence the location). They are unique components of Earth’s heritage. The ice formed there holds important paleoclimatic information and can be used to assess the global warming effect on the cryosphere in non-glaciated areas. We present an example from Wielka Śnieżna, the deepest cave system in the Polish Tatra Mountains, located in Tatra National Park (Tatrzański Park Narodowy). There have been no recent studies completed on the topic in this location. We provide the first contemporary results of temperature measurements by analysing microclimatic patterns and their response to global warming. There is ongoing ablation of the Ice Fall located in one of the lower entrances (Śnieżna) showing that the ice level has decreased by around 2 m in the last 10 years. The cave is under a minor human impact as it can be accessed only by professional cavers. However, some practices impact the balance of this fragile environment. By comparing our results with the outside temperature records, we aim to understand how dependent the cave microclimate is on the external fluctuations and changes. The ice in the Śnieżna is expected to be gone in the current century.

Cave-roosting specialisation of an oceanic island endemic microbat elevates extinction risks as caves face multiple threats

Bats (Chiroptera) constitute one-fifth of the global mammalian diversity, with over 1,450 species. Yet, 16.5 % of them are threatened with extinction, a situation exacerbated on islands, underscoring an urgent need for conservation efforts there. However, effective conservation action can only be as sound as the understanding of the basic ecology of such insular species. Mauritius harbours one endemic Endangered cave-roosting insectivorous bat, in recent decline, whose ecology is poorly known, hampering its conservation. We used Mormopterus acetabulosus as a model species to inform insectivorous island bat conservation in highly transformed habitats. We compared the species’ historical and current known roost distribution and sizes and estimated any change in its Area of Occupancy (AOO) and Extent of Occurrence (EOO) using GeoCAT. We also compiled the physical characteristics, environmental and anthropogenic variables of caves that are occupied and unoccupied by the bats to identify potential factors influencing roost occupancy. We found roosts in 17 of the recorded 130 lava cave tunnels, up from the nine previously recorded, including 11 permanent and six seasonal roosts, mostly (∼71 %) on privately owned land. Compared to the last surveys in 2017, the EOO remained stable at 818.9 km2, while the AOO increased by 33.3 %. This expansion may reflect previously undetected roosts or recent colonisation events or both. Cave dimensions in terms of entrance size and height as well as the number of chambers, relative humidity and distance to water best explained roost occupancy by M. acetabulosus. Caves with larger entrances may be preferred for roosting as this characteristic eases manoeuvrability and predator avoidance, and larger caves may be preferred for enhanced microclimatic stability. Occupied and unoccupied caves were found to differ in terms of physical characteristics, although cave microclimate did not vary notably. Based on their characteristics and their potential contributions to increasing the species’ EOO and AOO, six currently unoccupied caves were identified as priority sites for future conservation efforts. Legal protection of all caves, regardless of current bat occupancy is necessary to mitigate extinction risks and preserve their associated ecological functions.

My cave, my rules: Specialization, modularity, and topology of bat‐fly interactions in hot and cold caves from eastern South America

AbstractCaves provide relatively stable and advantageous roosting sites for bats compared to more open roosts, like tree foliage. This environment may have the drawback of facilitating interactions with their ectoparasites due to the confined spaces. Understanding the structure of interactions between bats, acting as hosts, and bat flies, serving as parasites in cave ecosystems, is a crucial first step in deciphering the roles of each species (pullers and pushers) within the networks that form in subterranean ecosystems. Here, we describe and evaluate the network structures of bat‐fly interactions in two distinct cave systems: cold caves (n = 10), also known as bat caves, and hot caves (n = 6). Based on the records of 700 bats from 16 species and 1.412 bat flies from 30 species we uncovered highly distinct topologies comparing hot and cold bat caves that differed also in terms of interactions, specializations, and modularity. We found relatively lower specialization and modularity in hot caves compared to the cold caves, which may be associated to the bat composition and the cave microclimate. Bat flies were highly species‐specific in relation to their bat hosts and dependent on the bats in both hot and cold caves systems. The differences in network structure and at the species level between the bat (cold) and hot caves systems suggest that bat‐fly interactions are shaped by the host species' composition and by the cave system type. Those differences stem from each bat species' adaptation to extreme cave microclimates and their species‐specific roosting behaviors.Abstract in Portuguese is available with online material.

Attenuating Anthropogenic Impact on Subterranean Micro-Climate: Insights from the Biospeleological Station in Postojna Cave

The Biospeleological Station (BS) in Postojna Cave, with a volume of 36,000 m3, has served as an underground biological laboratory since 1931, receiving 100,000 visitors annually. Historical cave micro-climate monitoring was performed in 1933 and 1963, and continuous monitoring of cave air temperature and carbon dioxide concentration at hourly intervals started in 2015. Micro-climatic data collected between 2015 and 2024 has helped us to understand the relationship between natural underground environment and anthropogenic impact, thereby aiding expert recommendations to cave managers for the mitigation of anthropogenic micro-climatic effects. Results strongly support the policy that, during summer, when outdoor temperatures are higher than in the cave, solid metal doors connecting the BS with the rest of the cave (Stara Jama) should be kept open. Such a simple mitigation act helps to decrease anthropogenically increased air temperature and carbon dioxide concentrations, thereby maintaining suitable micro-climatic conditions for the exhibition of cave animals. Closure during the COVID-19 pandemic (2020–2021) resulted in the lowest temperatures recorded. BS visitation increases air temperature by 1 °C, highlighting the need for management strategies to maintain suitable conditions for cave fauna exhibition.

Coupled heat and mass transfer in shallow caves: Interactions between turbulent convection, gas radiative transfer and moisture transport

Understanding and predicting the microclimate of shallow caves is a key issue for the conservation of parietal art. In order to determine the dominant mechanisms of heat transfer in a configuration close to that of painted caves, we performed numerical simulations of a parallelepiped cavity whose dimensions and depth are of the order of 10m. This simple geometry allowed us to use a detailed model including turbulent natural convection, gas radiation, along with vapor transport and latent heat fluxes resulting from condensation and evaporation on the walls.Gas radiation increases the flow circulation in the cavity through wall–gas radiative exchanges and significantly modifies the wall radiative flux. Conversely, the wall conductive flux remains unchanged (a non trivial behavior reported in the literature about the differentially heated cavity). In the energy balance at the walls, the radiative flux overcomes the conductive flux. However, the addition of conduction and latent heat fluxes, both driven by convection, prevails over radiation in some regions of the cavity.Heat and mass fluxes are maximum in areas of the cavity roof where the distance from the ground is the shortest. Due to the asymmetry induced by the inversion of the vertical temperature gradient twice a year, net condensation resulting in limestone dissolution is expected in these areas, whereas the other regions of the cave undergo net evaporation resulting in limestone deposition. The orders of magnitude of the condensation flux (a few microns per day) and of the retreat velocity of the wall (a few tenth of a micron per year) are in line with the field data available in the literature.

Spatiotemporal Variation Characteristics and Influencing Factors of Karst Cave Microclimate Environments: A Case Study in Shuanghe Cave, Guizhou Province, China

To systematically analyze the spatiotemporal heterogeneity, diurnal variation characteristics, and influencing factors of karst cave microclimate environments in Mahuang Cave, a cave in the Shuanghe Cave National Geological Park in Guizhou Province, China, was investigated. Monthly monitoring of meteorological and environmental parameters, such as wind speed, air pressure, humidity, and temperature indicators inside the cave and atmospheric temperature and precipitation outside the cave, was conducted from 2019 to 2021, as well as encrypted monitoring in August and December 2019. The results showed that: (1) The meteorological parameters of Mahuang Cave exhibited seasonal characteristics and cyclical interannual variation. Cave wind speed, relative humidity, and temperature were high in summer and autumn and lowest in winter, whereas cave air pressure was high in winter and low in summer. The atmospheric temperature outside the cave was the main controlling factor. (2) On a short time scale, the dewpoint and temperature of Mahuang Cave did not change significantly, and an abrupt change phenomenon occurred mostly around noon. The warm season was more sensitive than the cold season, and the closer to the entrance of the cave, the stronger the response. (3) In terms of spatial distribution, the overall microclimate factors of Mahuang Cave became increasingly stable and entered a constant state with the increasing depth of the cave passage. The related effects of cave morphology and structure, the physical environment of the cave passage, air movement, and groundwater dynamics were important factors leading to an abrupt change phenomenon in cave microclimates. Local meteorological conditions and cave geometry controlled the temporal variability and spatial heterogeneity of the cave microclimate environment.

Thermal conduction in karst terrains dominating cave atmosphere temperatures: Quantification of thermal diffusivity

The relatively stable temperature of most cave interiors is caused by the transfer of the surface atmosphere temperature signal to the karst underground by thermal conduction. Transferring underground thermal signals by conduction implies the amplitude attenuation of the external thermal anomaly as well as a signal delay. The magnitude of these attenuation and delay effects is proportional to the thickness of bedrock cover above the cave and is controlled by the bedrock thermal diffusivity. Here we present 5-year temperature record of Los Pilones Cave, in central Spain, where advection has a limited control on thermal anomalies all year round. Thus, thermal conduction dominates the thermal variability in the cave, with simulations of a 1-D thermal conduction model explaining up to 94% of the variability observed. Thermal attenuation and signal delays are highly correlated with the thickness of bedrock cover (r2 = 0.95 in both cases), enabling the calculation of a thermal diffusivity of 5.07*10−7 ±1.27*10−7 m2/s. The calculated thermal diffusivity is in the range of available values measured in laboratory for carbonate lithologies, although differs beyond uncertainty from the limited number of studies that calculated this value from field observations in karst. Thus, local rock properties significantly impact thermal diffusivities, and more experimental studies are required to show a complete distribution of this value in karst settings. The reported uncertainty, that was calculated using different time windows within the studied period, represents a variability of 23% on the thermal diffusivity. Karst terrains are mostly composed of three phases, rock, air and water, that have different thermal properties. Thus, variability of the water content in the rock porosity through time is likely a significant control on the measured uncertainty. Since temperature in the studied cave has a minor component affected by advection, this cave represents a paradigmatic location to observe the important role of thermal conduction in caves. Therefore, conclusions from this study can be useful to better understand thermal regimes and interannual trends of most cave interiors despite occurrence of variable impacts of seasonal ventilation dynamics in cave temperature records. In addition, the mechanism of thermal conduction results in a thermal decoupling between the surface and cave atmospheres affecting cave microclimate, which has important implications for multiple disciplines interested in karst underground environments.

Roost selection and ecology of Hipposideros pomona in China

Abstract Hipposideros pomona is a typical cave-dwelling bat (IUCN endangered), and its roost selection mechanism has not been studied. From January 2018 to December 2020, 135 potential roosts were investigated in mainland China. To understand the impact of cave microclimate, structure, surrounding and human disturbance on roost selection of H. pomona, 16 variables related to microclimate and roost characteristics were measured. The differences in environmental conditions in the roost of this species in different seasons were studied. The roost preferences of H. pomona were evaluated using independent-samples t-tests and chi-squared tests. The major environmental factors affecting the selection of roosts were determined by principal components analysis (PCA). The results were as follows: (1) H. pomona preferred free-hanging with a cluster spatial arrangement in small rooms deep in the caves. (2) H. pomona and other species of bats all tended to live in natural caves. However, compared to other bats, H. pomona preferred to roost in caves with relatively lower cave ceilings, more entrances, and farther from residential areas. Roosts of H. pomona were warmer and wetter with significantly lower levels of disturbance than those without H. pomona. (3) H. pomona preferred to hibernate in natural caves with little human disturbance and higher temperature and relative humidity. (4) Compared with nonbreeding roosts, breeding roosts of H. pomona had more areas covered by water and had a higher temperature and relative humidity. (5) The PCA analysis showed that microclimate factors, structure factors, and geographical factors were significant environmental factors for H. pomona roost selection.

Microclimatic characterization of tourist caves in Parque Nacional Cavernas do Peruaçu, Minas Gerais, Brazil

Abstract The cave environment has very peculiar atmospheric conditions that directly influence the existence and maintenance of biotic and abiotic, socioeconomic, and historical-cultural elements represented by or associated with caves. In caves where tourist activities occur, the human presence may affect the delicate balance of these conditions. This study was developed to characterize the cave microclimates of seven caves that are part of the tourist itinerary in the Parque Nacional Cavernas do Peruacu, located in the north of the state of Minas Gerais, Southeast Brazil. Temperature and relative humidity data were collected through 41 automated meters that each accumulated more than 110,300 readings. This research stands out for being one of the only long-term studies (2017 to 2019) developed in the country. The information analysis enabled not only characterization of the cave microclimate, but also observation of the relationship of these attributes with the internal morphology and the position of the caves in relation to the karstic relief of the region. The methodology developed in this study could support the Programa de Monitoramento das Condicoes Ambientais das Cavernas (Cave Environmental Conditions Surveillance Programme) to be implemented by the administration of the National Park, and identification of more sensitive environments in the interior of the caves will enable reordering of the visitation of these attractions.

ON PROBLEM OF CALCULATION OF CONDENSATION MOISTURE IN THE CAVES

Microclimate of karst caves are formed by the simultaneous process of heat and moisture (mass) exchange in the double-component thermodynamic system of “cave air - environment rock massif”. Cave formations in this case are belonged to the rock massif. The simultaneous heat-mass-transferring process can be considered as a simple process of transferring heat and mass, or isolation of heat transfer itself and the occurrences of evaporation and condensation for the purpose of simplifying the evaluation of the rests. Accordingly, relatively reliable must be the observations results on occurrences of evaporation and condensation in case when it is possible to isolate indicated simple processes from each other.

Understanding the linkage between regional climatology and cave geochemical parameters to calibrate speleothem proxies in Madagascar

Robust reconstructions of paleoclimate and paleoenvironmental changes using stalagmite proxy records critically depend on detailed observations of the transfer function between the regional climate/environment, the karst aquifer hydrology, and finally the cave microclimate via monitoring, which is currently lacking in Madagascar. This paper reports the first monitoring study performed in Anjohibe Cave, in Mahajanga, NW Madagascar to understand the linkage between regional climatological changes and cave responses to such changes. In this research, we monitored (1) the drip water pH, TDS, EC, temperature, δ13CDIC, δ18Ow, δ2Hw, and elemental (Ca, Mg, Sr) composition, and (2) the cave atmosphere pCO2, relative humidity (RH) and temperature.Three significant findings were drawn from the results. First, the data show that air-to-air transfer is fast, and the internal parameters closely vary with the regional climatology. Second, rainfall to drip signal transfer is not immediate, and it can take few months to one season for the signals to be detected in the drip water due to the “epikarst storage effect”. Lastly, CaCO3 precipitation is likely to occur during the winter-summer transition, during which prior carbonate precipitation was detected. Since the growth of speleothems is influenced by numerous cave-specific factors, this study, although preliminary, indicates that Anjohibe Cave drip waters are capable of registering changes in its surrounding environment. Such information is ultimately archived in speleothems to reconstruct paleoclimate and paleoenvironmental changes. Results from this research will be of high significance for those working on speleothems within Madagascar, and for those working on understanding the transfer of climatic variations to cave deposits.

Stay or shift: does breeding success influence the decision in a cave-dwelling swiftlet?

Decision rules allow individuals of a species to decide whether or not to return to the same site in the following year or season, based on their immediate breeding success. We checked the decision rule phenomenon and simultaneously tested the prior-experience hypothesis for the cave-dwelling Edible-nest Swiftlet (Aerodramus fuciphagus inexpectatus; ENS) in the Baratang Cave Complex, Andaman and Nicobar Islands, India. We used the capture-mark-recapture method to understand the decision rule in ENS. Assuming that breeding success affects the decision, we monitored 234 individuals for two consecutive breeding seasons (2017 and 2018). We also documented habitat variables (cave morphometry and microclimate) to understand the correlates of breeding success. We captured 88% (207 birds) of adult birds from the study caves in 2017 and recaptured 66% (137 birds) of adults from the same caves in 2018, which confirmed fidelity towards the cave by the species. There was no significant correlation between the rates of breeding success in 2017 and 2018. Multiple regression models revealed an insignificant relationship between cave structure and breeding success of the species. Additionally, microclimate variables (temperature and humidity) did not influence the breeding success of the birds. Our results indicate that ENS individuals seem to chose decision rule by rejecting the prior-experience hypothesis. The existing conservation strategies associated with enhancing the ENS population in the Andaman and Nicobar Islands can benefit from our findings. We further recommend long-term studies and population monitoring to understand the breeding cave fidelity in ENS.

Ice caves on Mars: Hoarfrost and microclimates

Caves on planet Mars could potentially contain water ice deposits. Here, the physical processes responsible for the growth and preservation of spelean ice formations on Mars are assessed. Martian caves are situated in environments where phase transitions of water are only by sublimation. The predominant type of cave ice is expected to be perennial hoarfrost that slowly grows in supersaturated cavities. The role of cave microclimates for maintaining ice bodies is evaluated comparatively. Free and forced convection transport less sensible heat than in the denser terrestrial atmosphere. Cooling through sublimation is also expected to be far weaker in Martian caves than in terrestrial caves. Hence, the cooling of ice deposits by flow through the cave, often a crucial factor in terrestrial ice caves, is insignificant on Mars, which limits the geographic extent where cave ice deposits can be expected.

Global models for 222Rn and CO2 concentrations in the Cave of Altamira

The purpose of this paper is to model numerically the dynamics of CO2 and 222Rn in cave atmospheres, particularly in the noteworthy Cave of Altamira (Spain). We aim to get a better understanding of the nature of these dynamics and their couplings with climatic controls, more specifically the soil water content, which role in the said dynamics poses some questions. For the first time, we apply the global modeling technique in the field of cave microclimate and atmospheric composition. The global modeling technique is a methodology based on the theory of nonlinear systems and designed to extract mathematical models directly from observational time series. We were able to extract four global models from our data. These models represent a step forward from the existent conceptual ones. They also show that CO2 and 222Rn dynamics can be approximated by low-dimensional, deterministic systems, which can be chaotic or, at least, close to chaos; this has decisive methodological consequences for future research. Moreover, the global modeling technique was used for the first time in a non-autonomous formulation; this enabled the possibility of studying the influence of the external forcing (soil water content) on the gas concentration in different scenarios.

Impact of visits on microclimate of caves – An analytical approach

The theoretical basis for describing natural steady-state conditions in caves as well as for their changes in time that follow from the simple advection-diffusion equation, is given. The impacts of visits to caves – direct impacts due to anthropogenic emissions of heat and CO2, as well as indirect ones, such as illumination and possible drafts when opening the door to the cave – are estimated in dependence to the number of visitors and the size of the cave: the size with which the effects of the visits are below the detection threshold is estimated. It is shown that the sources cause linear responses, while the consequences of the exchange with the walls of the cave or with the exterior depend on time exponentially. Characteristic times for linear as well as for exponential responses are roughly estimated.

Linking surface and subterranean climate: implications for the study of hibernating bats and other cave dwellers

AbstractCaves and other subterranean features provide unique environments for many species. The importance of cave microclimate is particularly relevant at temperate latitudes where bats make seasonal use of caves for hibernation. White‐nose syndrome (WNS), a fungal disease that has devastated populations of hibernating bats across eastern and central North America, has brought renewed interest in bat hibernation and hibernaculum conditions. A recent review synthesized current understanding of cave climatology, exploring the qualitative relationship between cave and surface climate with implications for hibernaculum suitability. However, a more quantitative understanding of the conditions in which bats hibernate and how they may promote or mediate WNS impacts is required. We compiled subterranean temperatures from caves and mines across the western United States and Canada to (1) quantify the hypothesized relationship between mean annual surface temperature (MAST) and subterranean temperature and how it is influenced by measurable site attributes, and (2) use readily available gridded data to predict and continuously map the range of temperatures that may be available in caves and mines. Our analysis supports qualitative predictions that subterranean winter temperatures are correlated with MAST, that temperatures are warmer and less variable farther from the surface, and that even deep within‐cave temperatures tend to be lower than MAST. Effects of other site attributes (e.g., topography, vegetation, and precipitation) on subterranean temperatures were not detected. We then assessed the plausibility of model‐predicted temperatures using knowledge of winter bat distributions and preferred hibernaculum temperatures. Our model unavoidably simplifies complex subterranean environments and is not intended to explain all variability in subterranean temperatures. Rather, our results offer researchers and managers improved broad‐scale estimates of the geographic distribution of potential hibernaculum conditions compared to reliance on MAST alone. We expect this information to better support range‐scale estimation of winter bat distributions and projection of likely WNS impacts across the west. We suggest that our model predictions should serve as hypotheses to be further tested and refined as additional data become available.

Tourism effects on the subterranean fauna in a Central American cave

Abstract Tourism activity affects the cave's physical environment in several ways, such as damaging speleothems, altering the cave structure for ease of access, and the shifting of cave microclimate. Nevertheless, it is less clear how the pressure of touristic activities affects the cave fauna. This study aimed to investigate the effects from tourism activities on the cave invertebrate fauna from Gruta de Lanquín Cave (Alta Verapaz, Guatemala). For this, quadrats were placed throughout the cave, where invertebrates were sampled and substrate features were measured. Results showed that the community structure differed among touristic and non‐touristic areas of the cave and the troglobitic species are structured differently than the rest of the invertebrate community in the cave. It was detected that the pathways designated for touristic use have different substrate features than their adjacent areas. In order to maintain the conservation of the invertebrate species, several management recommendations are provided, such as determining a well‐established walking path that avoids cave microhabitats and the maintenance of a supervised guided tour.

Pacific climate reflected in Waipuna Cave drip water hydrochemistry

Abstract. Cave microclimate and geochemical monitoring is vitally important for correct interpretations of proxy time series from speleothems with regard to past climatic and environmental dynamics. We present results of a comprehensive cave-monitoring programme in Waipuna Cave in the North Island of New Zealand, a region that is strongly influenced by the Southern Westerlies and the El Niño–Southern Oscillation (ENSO). This study aims to characterise the response of the Waipuna Cave hydrological system to atmospheric circulation dynamics in the southwestern Pacific region in order to assure the quality of ongoing palaeo-environmental reconstructions from this cave. Drip water from 10 drip sites was collected at roughly monthly intervals for a period of ca. 3 years for isotopic (δ18O, δD, d-excess parameter, δ17O, and 17Oexcess) and elemental (Mg∕Ca and Sr∕Ca) analysis. The monitoring included spot measurements of drip rates and cave air CO2 concentration. Cave air temperature and drip rates were also continuously recorded by automatic loggers. These datasets were compared to surface air temperature, rainfall, and potential evaporation from nearby meteorological stations to test the degree of signal transfer and expression of surface environmental conditions in Waipuna Cave hydrochemistry. Based on the drip response dynamics to rainfall and other characteristics, we identified three types of discharge associated with hydrological routing in Waipuna Cave: (i) type 1 – diffuse flow, (ii) type 2 – fracture flow, and (iii) type 3 – combined flow. Drip water isotopes do not reflect seasonal variability but show higher values during severe drought. Drip water δ18O values are characterised by small variability and reflect the mean isotopic signature of precipitation, testifying to rapid and thorough homogenisation in the epikarst. Mg∕Ca and Sr∕Ca ratios in drip waters are predominantly controlled by prior calcite precipitation (PCP). Prior calcite precipitation is strongest during austral summer (December–February), reflecting drier conditions and a lack of effective infiltration, and is weakest during the wet austral winter (July–September). The Sr∕Ca ratio is particularly sensitive to ENSO conditions due to the interplay of congruent or incongruent host rock dissolution, which manifests itself in lower Sr∕Ca in above-average warmer and wetter (La Niña-like) conditions. Our microclimatic observations at Waipuna Cave provide a valuable baseline for the rigorous interpretation of speleothem proxy records aiming at reconstructing the past expression of Pacific climate modes.

Correspondence between bats population and terrestrial cave-dwelling arthropods community in Tasikmalaya karst area

Trogloxenes particularly bats play an important role in subterranean habitat. They provide organic material and induce cave microclimate that influence cave-dwelling biota, including arthropods. This study aimed to learn how bats population influences cave-dwelling arthropods community. Data collections were performed in three caves which had different bats species in Tasikmalaya karst area namely Liang Boeh, Liang Seungit and Sarongge. We recorded bats population, guano production, physicochemical condition of caves passage, and arthropods community in each cave. All samplings were only conducted in the specific sites of the dark zone where bat populations were aggregated. Data indicated that Liang Boeh was inhibited by Hipposideros sp (±472 individuals), Liang Seungit by Pteripodidae and Miniopterus sp. (±188 individuals), and Sarongge by Rhinolophus sp. (±1194 individuals). Guano production was positively correlated with bats population. Chemical compositions of soil were varying among bats species. Bats population strongly induced caves physicochemical condition. A total 15986 individuals of cave-dwelling arthropods belonging to 5 Classes and 18 Orders were recorded. Our result revealed that bats population determined arthropods community. Caves with greater bats population size and dominated by insectivorous species would potentially have greater diversity and abundance of cave-dwelling arthropods.

Microclimatic characteristic of the Chelevechnitsata cave in Western Rhodopes

Chelevchinitsa Cave is formed in the southwestern part of the Dobrostan karst region, Western Rhodopes. It has been subjected to microclimatic monitoring since April 2016. Air temperature, cave water and sediments are periodically measured at eight points, and thus the air humidity is determined. A micro-climatic zoning of the cave was being done on the basis of the analysis of the data on the temperature regimes for the period 2016–2018. A link has been sought between cave microclimate and global climate change using available data for the period 1979–2017 . The issue of the influence of the anthropogenic load on the speleomicroclimate as well as the impact of the cave enviorment on the health and safety of the tourists is also discussed. Particular attention is paid to the role of cave ventilation on the gas composition of the cave atmosphere, and especially on the regime of carbon dioxide (CO2 ) and radon (222Rn).