Cave Entrance Research Articles

Conservation concern’ bryophytes find refuge on cave entrances in the Azores

Bryophytes, including mosses, liverworts and hornworts, are terrestrial plants, with a particular life cycle where the gametophyte is dominant over the sporophyte; many species are pokilohydric, meaning that they achieve a quick equilibrium between the cell water content and that of the environment, suspending their life, but not dying, in the absence of water. Due to their light spores, these plants have a great dispersal ability and may be found from the poles to the equator. In the Azores, there are almost 500 species (Gabriel et al. 2010), colonizing a large number of habitats and substrata, but forming particularly luxuriant communities inside native forests. Nevertheless, these forests are presently restricted to medium-high elevations (above 500 m) and below this altitude, adequate habitats for many bryophyte species are scarce (Henriques et al. 2016). Cave entrances, at different elevations, serve as surrogate habitats for bryophyte species, since they present an adequate relative humidity, fewer competitor species and are usually not disturbed by chemical products such as herbicides or pesticides. The aims of this work are twofold: present the results of the first IUCN red-list assessment of the conservation status of Azorean conservation concern bryophytes; and present an overview of the major threats involving the conservation of those species. present the results of the first IUCN red-list assessment of the conservation status of Azorean conservation concern bryophytes; and present an overview of the major threats involving the conservation of those species. The assessments of extinction risk were based on the most updated categories and criteria. Seven liverworts (Calypogeia azorica, Cheilolejeunea cedercreutzii, Fuscocephaloziopsis crassifolia, Leptoscyphus porphyrius subsp. azoricus, Lophocolea fragrans Plagiochila longispina and Radula holtii,) and seven mosses (Andoa berthelotiana, Echinodium renauldii, Heterocladium flaccidum, Hookeria lucens, Microcampylopus laevigatus, Rhynchostegiella trichophylla and Thamnobryum rudolphianum) benefit from populations at cave entrances, mostly the Azorean and Macaronesian endemic species. The three most common threats harming “cave” bryophytes include: climate change & severe weather, habitat change and degradation and invasive plant species of native forest. These threats are also documented in the literature (e.g. Patiño et al. 2016; Ferreira et al. 2016; Triantis et al. 2010 and Silva et al. 2008). Cave habitats are thus an important part of bryophyte conservation in the Azores, and should be both legally protected and monitored to the mutual benefit of species and habitat conservation.

Ten new species of the spider genus Althepus Thorell, 1898 from Southeast Asia (Araneae, Ochyroceratidae).

Spiders of the genus Althepus Thorell, 1898 are found throughout Southeast Asia, notable for their long walking legs. Ten new species are reported in this paper from China, Indonesia, Laos and Myanmar: A.chengmenensis Li & Li, sp. n. (♂♀), A.cheni Li & Li, sp. n. (♂♀), A.gouci Li & Li, sp. n. (♂♀), A.hongguangi Li & Li, sp. n. (♂♀), A.phousalao Li & Li, sp. n. (♂♀), A.qianhuang Li & Li, sp. n. (♂♀), A.qingyuani Li & Li, sp. n. (♀), A.sepakuensis Li & Li, sp. n. (♂♀), A.xuae Li & Li, sp. n. (♂♀) and A.yizhuang Li & Li, sp. n. (♂♀). These species were found in cave entrances and among tree-buttresses, indicating the spiders have a preference for dark and moist environments. All types are deposited in the Institute of Zoology, Chinese Academy of Sciences in Beijing, China (IZCAS).

Diversity of Fungal Communities in Heshang Cave of Central China Revealed by Mycobiome-Sequencing.

Deciphering of the mycobiome in pristine karst caves has been impeded by constraints of remote locations, inaccessibility to specimens and technical limitations, which greatly restricted in-depth understanding of mycobiomes in subterranean ecosystem. Here, mycobiomes of Heshang Cave in south-western karst region of China were investigated by Illumina HiSeq sequencing of fungal rRNA-ITS1 gene across different habitats. In total 793,502 ITS1 reads and 2,179 OTUs from 778 Mb reads after stringent quality control (Q30) and 453 genera, 72 orders and 19 classes within 6 phyla were detected. Ascomycota (42% OTUs) dominated across the five habitats. Shannon-Wiener index varied from 1.25 to 7.62 and community richness was highest in drip waters, followed by weathered rocks, bat guanos, sediments, and air samples. Mycobiomes displayed specificity to five habitats and more distinct OTUs were found in weathered rocks (12%) and drip waters (9%). In contrast, only 6.60% core OTUs were shared by five habitats. Notably, weathered rocks possessed more indicator groups and were revealed for the first time to be dominated by Sordariomycetes (43%). The community richness of air mycobiomes increased from cave entrance to the innermost part and dominated by the indicator groups of Penicillium mallochii (>30%) and P. herquei (>9%). Our work represents the largest attempt to date to a systematical investigation of oligotrophic solution-cave-associated mycobiomes in China. Our discovery of high diversity of mycobiomes in Heshang Cave also suggests that eukaryotic microorganisms may play a crucial role in subsurface environments.

Distance interaction between marine cave-dwelling sponges and crustaceans

Sponges are benthic organisms that are dominant in several ecosystems and known to produce a huge chemical diversity. The putative release of some specialized metabolites in the surrounding seawater is still a matter of debate, but the presence of such compounds in the environment of sponges is thought to influence the behaviour of various mobile organisms and may, thus, contribute to benthic ecosystem structuring and functioning. Underwater Mediterranean caves are characterized by stable environmental conditions and sessile species assemblages dominated by sponges. A two-choice test system was developed to assess the response of two cave-dwelling crustaceans (Hemimysis margalefi and Palaemon serratus) and two other species living in shallow water environments (Leptomysis sp. and Palaemon elegans) to various seawater treatments: control− seawater from an exposed coastline, control+ seawater coming from an underwater cave, and seawater conditioned with four Mediterranean sponges commonly found at the entrance of underwater caves (Aplysina cavernicola, Haliclona fulva, Oscarella tuberculata and Spongia officinalis) or their chemical extracts. We tested the swimming behaviour of these crustacean species in three complementary experiments: (1) control seawater vs. cave seawater; (2) control seawater vs. seawater conditioned with the sponge community, (3) control seawater vs. seawater containing chemical extracts of the same sponge community. Both cave-dwelling crustaceans were attracted by the seawater conditioned with the sponge community, while Leptomysis sp. spent more time in the control seawater and P. elegans exhibited indifferent responses. All four crustacean species avoided the seawater containing the sponge extracts. Interestingly, the response shown by the crustaceans was affected by the time of day. A comparative and untargeted metabolomic approach was applied to the surrounding seawater to identify putative chemomarkers that could explain the crustaceans’ behaviours. Among other compounds found in the seawater, a family of metabolites with molecular formulae in accordance with those of oxylipin derivatives is released by sponges and may, therefore, serve as chemical cues acting as kairomones in the homing behaviour of cave-dwelling crustaceans.

Sponge community of the western Black Sea shallow water caves: diversity and spatial distribution.

Marine caves possess unique biocoenotic and ecological characteristics. Sessile benthic species such as sponges associated with cave habitats typically show a marked zonation from the cave entrance towards the end of the cave. We describe three semi-submerged karstic caves of 50 to 83 m length and 936 to 2,291 m3 volume from the poorly explored cavernicolous fauna of North-East Bulgaria. We surveyed sponge diversity and spatial variability. Eight demosponge species were identified based on morphological and molecular data, of which six are known from the adjacent open sea waters of the Black Sea. Two species, Protosuberites denhartogi van Soest & de Kluijver, 2003 and Halichondria bowerbanki Burton, 1930, are reported from the Black Sea for the first time. The spatial sponge distribution inside the caves is in general similar, but shows some differences in species composition and distribution depending on cave relief and hydrodynamics. The species composition of sponges of Bulgarian caves is found to be different from Crimean caves. An updated checklist of the Black Sea sponges is provided.

Short Communication: Cave-dwelling Arthropod community of Semedi Show Cave in Gunungsewu Karst Area, Pacitan, East Java, Indonesia

Kurniawan ID, Rahmadi C, Caraka RE, Ardi TE. 2018. Short Communication: Cave-dwelling Arthropod community of Semedi Show Cave in Gunungsewu Karst Area, Pacitan, East Java, Indonesia. Biodiversitas 19: 857-866. Arthropods are a major group of animals which have significant roles in maintaining cave ecosystem stability. Semedi is a new show cave, but information about arthropods in this cave was not available. The use of cave as a tourist attraction will bring environmental changes which potentially disturb cave-dwelling arthropod community. This study aimed to measure arthropod diversity and their relation to abiotic factors in Semedi Show Cave. Arthropods were sampled by hand collecting, a combination of pitfall and bait traps, and Berlese extractor. Abiotic factors measured were climatic and edaphic parameters. Sampling was conducted in the 3 zones of Semedi cave (Entrance, Twilight, and Dark). Data were analyzed by calculation of richness (Margalef), diversity and evenness (Shannon-Wiener) indices, cluster and correlation analyses. A total 1095 individuals of arthropods consisting of 102 morphospecies, belonging to 6 Classes, and 19 Orders were sampled during this study. The entrance zone had higher richness and diversity indices (richness=12.80, diversity=3.40) than the twilight zone (richness=7.85, diversity=3.25) and the dark zone (richness=5.35, diversity=2.63). Meanwhile, the twilight zone had higher evenness index (0.85) than the entrance zone (0.77) and the dark zone (0.77). Each zone of Semedi cave had different abiotic conditions. Abiotic conditions and Arthropod communities in the twilight and dark zones were more similar to each other than to those of the entrance zone. The statistical analyses showed that there were significant correlations between abiotic factors and arthropod communities. Semedi had various cave-dwelling arthropods. Sustainable management of show cave should be applied to minimize the destructive impact of tourism activities on the cave arthropod community.

The genus Vietbocap Lourenço & Pham, 2010 in the Thien Duong cave, Vietnam: A possible case of subterranean speciation in scorpions (Scorpiones: Pseudochactidae)

Two new species of scorpion belonging to the family Pseudochactidae and to the genus Vietbocap are described based on specimens collected in the Thien Duong cave, which belongs to the Vom cave system, in the Phong Nha–Ke Bang National Park, Quang Binh Province, Vietnam. The previously described species from this cave, Vietbocap thienduongensis Lourenço & Pham, 2012 was collected in the initial section of the cave (1500 to 1800m from the cave entrance) and proved to be a true troglobitic element. The diagnosis of this species, only known from males, is completed based on females collected at 750m from the cave entrance. The two new species described here were collected respectively at 3000 and 5000m from the cave entrance and are also true troglobitic elements, very similar to V. thienduongensis, but showing some clear morphological differences. This observed situation suggests a possible case of speciation within the cave system, the first one ever reported for scorpions. The population found at 5000m from the entrance of the cave is a total new record of distance from a cave entrance for scorpions.

Is the Italian stream frog (Rana italica Dubois, 1987) an opportunistic exploiter of cave twilight zone?

Studies on frogs exploiting subterranean environments are extremely scarce, as these Amphibians are usually considered accidental in these environments. However, according to recent studies, some anurans actively select subterranean environments on the basis of specific environmental features, and thus are able to inhabit these environments throughout the year. We present the first study on the abundance and spatial use of the Italian stream frog, Ranaitalica, in subterranean environments. We monthly collected data from 66 cave sectors during a whole year (2013), recording > 120 detections of R.italica. Frogs were more frequently found close to the cave entrance, without significant differences between age classes or sexes. Adults generally were observed being higher up along cave walls compared to juveniles. Frogs abundance was higher in areas showing specific environmental features, such as warm temperature, low incident light and the presence of potential prey. Ranaitalica likely occupies subterranean areas characterized by a combination of microclimatic suitability and prey availability.

Assessing site formation and assemblage integrity through stone tool refitting at Gruta da Oliveira (Almonda karst system, Torres Novas, Portugal): A Middle Paleolithic case study.

We use stone tool refitting to assess palimpsest formation and stratigraphic integrity in the basal units of the Gruta da Oliveira archeo-stratigraphic sequence, layers 15–27, which TL and U-series dating places in late Marine Isotope Stage (MIS) 5 or early MIS 4. As in most karst contexts, the formation of this succession involved multiple and complex phenomena, including subsidence, bioturbation, carnivore activity and runoff as agents of potential post-depositional disturbance. During phases of stabilization, such as represented by layers 15, 21 and 22, the excavated area was inhabited and refits corroborate that post-depositional displacement is negligible. Layers 23–25 and 16–19 correspond to subdivisions that slice thick geological units primarily formed of material derived from the cave’s entrance via slope dynamics. Refit links are consistent with rapid fill-up of the interstitial spaces found in the Karren-like bedrock (for layers 23–25), or left between large boulders after major roof-collapse events (for layers 16–19). Layers 26 (the “Mousterian Cone”) and 27 are a “bottom-of-hourglass” deposit underlying the main sedimentary body; the refits show that this deposit consists of material derived from layers 15–25 that gravitated through fissures open in the sedimentary column above. Layer 20, at the interface between two major stratigraphic ensembles, requires additional analysis. Throughout, we found significant vertical dispersion along the contact between sedimentary fill and cave wall. Given these findings, a preliminary analysis of technological change across the studied sequence organized the lithic assemblages into five ensembles: layer 15; layers 16–19; layer 20; layers 21–22; layers 23–25. The lower ensembles show higher percentages of flint and of the Levallois method. Uniquely at the site, the two upper ensembles feature bifaces and cleavers.

Hymenasplenium hastifolium sp. nov. (Aspleniaceae) from a karst cave in western Guangxi, China

A new fern species, Hymenasplenium hastifolium (Aspleniaceae), from a limestone cave in western Guangxi, China, is described and illustrated. Morphological affinities of genus Hymenasplenium are also compared and discussed. The new species is distinguished by the shape of lamina, the venation, and the sorus distribution. Hymenasplenium hastifolium was found at a cave entrance and is currently known only from one population with ca. 50 individuals. It should be classified as Critically Endangered (CR) following IUCN Red List criteria.

Distribution Pattern of Cave Entrance Based on Morphometry in Gunung Sewu Karst Landscape

Wonosari-Punung Formation of Middle Miocene-Pliocene and Semilir Formation of Early-Middle Miocene consists of Gunung Sewu Karst Landscape in Ponjong and Semanu District; Gunungkidul Regency. Gunung Sewu Karst Landscape has advanced karstification so that the morphology of exokarst and endokarst could be formed. Cave entrance as a marker of the endokarst morphology existence is formed by varying morphometry. This research aims to determine cave entrance distribution pattern based on a cave entrance morphometry. These research variables are cave entrance morphometry; geological formation; and geological structure (geological lineament). The analytical method uses nearest neighbour analysis (NNA) and lineament analysis. The result of this research shows that vertical cave entrance with oval; narrow; and irregularity shape have dispersed distribution pattern in Wonosari-Punung Formation. Horizontal cave entrance with irregular; rectangular; narrow; and an oval shape; have clustered pattern of distribution in the Wonosari-Punung and Semilir Formations. This research is used as a preliminary study for the development of underground water resources that are commonly found in caves of Gunung Sewu Karst Landscape.

Simulation of Airflow in the Burning Cave of an Auxiliary Heating System in a Greenhouse

Abstract. In this study, numerical simulations of airflow were carried out in the burning cave of an auxiliary heating system. Experimental measurements were also conducted to verify the performance of the numerical model, and turbulent airflow in the burning cave was considered. The numerical simulation in the burning cave was performed for three cases:(1) with a baffle at the bottom of the burning cave entrance, (2) without a baffle at the burning cave entrance, and (3) with a baffle at the top of the burning cave entrance. The turbulent airflow was modeled using the realizable k-e turbulence model as well as the non-equilibrium wall function. The airflow velocity was assessed in the burning cave, and some suggestions were given to improve the performance of the burning cave. The results showed that the airflow entering the burning cave differed due to different positions of the baffle. The smoldering combustion was more even and the burning rate could be controlled more easily when the baffle was placed at the top of the burning cave entrance, making the airflow enter the burning cave through the bottom of the baffle. The results also showed that the maximum airflow velocity in the burning cave increased with increased distance between the baffle and the bottom of the burning cave. Keywords: Airflow, Burning cave, Greenhouse, Simulation.

A Giant Underwater, Encrusted Stalactite from the Blue Hole, Lighthouse Reef, Belize, Revisited: a Complex History of Biologically Induced Carbonate Accretion Under Changing Meteoric and Marine Conditions

A late Pleistocene to Holocene submerged and encrusted speleothem exhibits a complex history including a meteoric phase and two marine phases. A combined study using petrography, mineralogy, and inorganic and organic geochemistry, as well as geochronology has shown that phototrophic and heterotrophic biological activity impacted carbonate precipitation during all phases of carbonate accretion. The stalactite formed ca. 30 m below modern sea level at a marginal overhang in the Blue Hole of Lighthouse Reef Atoll. Unlike purely meteoric speleothems, the Belize example consists of a meteoric core, a marine aragonite crust, and a serpulid-micrite-rich outer crust as a result of postglacial flooding of the karst cave. The core of the stalactite has a tufaceous texture, containing algal or microbial remains, and consists entirely of low-magnesium calcite, formed 19.55-10.68 kyr BP. The texture suggests that the stalactite formed at the cave entrance, and, hence, the former cave ceiling had apparently collapsed earlier during the Pleistocene. Oxygen (δ18O) and carbon (δ13C) isotopes across the core suggest a trend towards drier conditions and reduced soil and plant cover after the last glacial maximum. The marine aragonite crust consists of stacked botryoids in which individual crystals up to 700 lm have dark terminations enriched in high-magnesium calcite. This crust accreted from 10.82 to 9.95 kyr BP in warm shallow water during the early Holocene thermal optimum. Carbonate accretion rates were considerable and averaged 125 μm/yr. The crust has a dense, laminated texture on one side and a porous, shrubby texture on the other. The presence of n-C16:1ω5, n-C17:1ω6, and 10Me-C16 fatty acids in the laminated crust suggests that sulfate-reducing bacteria contributed to aragonite formation in an environment that was less open than the formation environment of the porous crust, where these biomarkers are lacking (n-C16:1ω5,n-C17:1ω6) or are less abundant (10Me-C16). Enrichment of 34S and 18O in carbonate-associated sulfate (CAS) relative to seawater sulfate also suggests sulfate reduction during carbonate formation. The greater contribution of heterotrophic processes to aragonite precipitation in the laminated crust is also reflected in δ13C values as low as -1.3%, whereas no such depletion is observed in the aragonite of the porous crust (δ13C values as low as 0.0%). A pronounced isotopic variability and excursions to positive δ13C values as high as +3.5%0 in the inner half of the laminated crust indicate an episodic, local impact of photosynthesis on aragonite precipitation, whereas the lack of such excursions in the porous crust (δ13C values as high as +1.5%0) is again best explained by a more open environment of formation. After a ca. 5 kyr hiatus, from 4.39 kyr BP, a biogenic crust of abundant serpulids and finely crystalline, microbial and detrital carbonate, consisting of high-magnesium calcite and aragonite, accreted on the outer surface of the stalactite. Outermost crust accretion was probably influenced by the inundation of the Lighthouse Reef lagoon that started to shed abundant fine-grained carbonate sediment into the Blue Hole. The stalactite broke off the cave ceiling either before or after the formation of the outermost crust, likely due to seismic movements along the nearby plate boundary. The study demonstrates that like speleothems from the terrestrial realm, submerged stalactites may have had complex histories with great potential as paleoenvironmental archives.

Polystichum zhijinense (subg. Haplopolystichum; Dryopteridaceae), a new cave species of Polystichum from Guizhou, China

A new fern species, Polystichum zhijinense, a member of P. subg. Haplopolystichum (Dryopteridaceae), is described and illustrated from Guizhou Province in Southwest China. Polystichum zhijinense is somehow similar to P. fengshanense in having pinnae oblong and entire or shallowly repand (not aristate-spinulose on the margin), but differs in the shape of the pinna apex, the morphology of microscales, and the sorus distribution. Polystichum zhijinense was found at a cave entrance and is currently known from one population only and thus is classified as Critically Endangered (CR) following IUCN Red List criteria.

Formation mechanism of large sinkhole collapses in Laibin, Guangxi, China

On June 3, 2010, a series of karst sinkholes occurred at Jili village surrounded by Gui-Bei highway, Wu-Ping highway and Nan-Liu High-Speed Railway in Laibin, Guangxi, China. The straight-line distances from an large sinkhole pit, 85 m in diameter and 38 m in depth, to the above mainlines are 200, 600 and 500 m, respectively. Several investigation methods including geophysical technology, borehole and well drilling, groundwater elevation survey and hydrochemistry analysis of groundwater were used to study the formation mechanisms of these sinkholes. Based on the results, the spatial distribution of the Jili underground river was confirmed with a strike of SN along the middle Carboniferous limestone bedrock and the Quaternary deposits controlled the sinkhole formation. In addition, both historical sinkhole events and analysis of the groundwater–air pressure monitoring data installed in the underlying karst conduit system indicate that sinkholes in this area are more likely induced by extreme weather conditions within typical karst geological settings. Extreme weather conditions in the study area before the sinkhole collapses consisted of a year-long drought followed by continuous precipitation with a daily maximum precipitation of 442 mm between May 31 and June 1, 2010. Typical geological conditions include the Jili underground river overlain by the Quaternary overburden with thick clayey rubble. Especially in the recharge zone of the underground river, a stabilized shallow water table was formed in response to the extreme rainstorm because of the presence of the thick clayey rubble. When the underground conduit was flooded through the cave entrance on the surface, air blasting may have caused the cave roof collapse followed by formation of soil cavities and surface collapses. Borehole monitoring results of the groundwater–air pressure monitoring show that the potential karst sinkhole can pose threats to Shanbei village, the High-Speed Railway and the Wu-Ping highway. Local government needs to be aware of any early indicators of this geohazard so that devastating sinkholes can be prevented in the future. The results also suggest that groundwater–air pressure monitoring data collected both the Quaternary deposits and the bedrock karst system provide useful indicators for potential sinkhole collapses in similar karst areas where sinkholes usually occur during rainy season or karst groundwater level is always under the rockhead.

Changes in the midgut cells in the European cave spider, Meta menardi, during starvation in spring and autumn.

During the growth period, in surface habitats, spiders catch enough prey to feed normally. In contrast, in the cave entrance zone, prey may be relatively scarce. Meta menardi inhabits this cave section, resulting in temporary starvation. We studied structural changes in the midgut epithelial cells of M. menardi during a short-term and a medium-term controlled starvation to mimic the occasional starvation in caves, during spring and autumn. Digestive cells, secretory cells and adipocytes were examined before the experimental starvation, in the middle and at the end of starvation. We used light microscopy, transmission electron microscopy and specific histochemical methods for the detection of lipids, polysaccharides and proteins. Detection of lysosomes, autolysosomes and apoptosis was also carried out. The general structures of the cells did not change during the experimental starvation in either season, while some specific differences in the ultrastructure were observed. In both sexes, in both seasons, the amounts of lipids, glycogen and proteins decreased during starvation. Larger amounts of lipids were found in autumn, while there were no significant differences in the amounts of glycogen and proteins. In both sexes, in both seasons, autophagy and apoptosis intensified with starvation in progress, but more intensively in females. Thus, autumn individuals, in contrast to spring ones, compile energy-supplying stores to confront the subsequent winter deficiency of prey in caves, while the cellular ultrastructures undergo the same starvation-dependant changes at any time during the growth period.

The cephalic morphology of free-living and cave-dwelling species of trechine ground beetles from China (Coleoptera, Carabidae)

Morphological adaptations of cave-dwelling organisms including different groups of Coleoptera have fascinated researchers since a long time. Nevertheless, very few detailed documentations of the anatomy of cave beetles using modern techniques are available. In this study, we describe and illustrate external and internal cephalic features of free-living and cave-dwelling trechine carabid beetles using digital microscopy, SEM, micro-CT, and computer-based 3D reconstruction. Morphological characteristics found in three selected species with different habitat preferences are compared. The following derived features distinguish a troglobite species (Sinaphaenops wangorum Ueno et Ran 1998) from a species living in the entrance of caves (Trechiotes perroti Jeannel 1954) and from a fully epigean species (Bembidion sp.): (1) the optic lobes are completely missing; (2) the head capsule, mouth parts, and antennae are distinctly elongated; (3) some muscle attachment areas are shifted; and (4) an additional dilator of the pharynx is present. Despite of conspicuous differences likely related with subterranean habits, the link of some cephalic features to this specific habitat preference remains uncertain.

Črna Jama as a cold air trap cave within Postojna Cave, Slovenia

Crna Jama is the coldest section of cave within the Postojna Cave System. Mean annual air temperatures at the Crna Jama 2 site are 5.6 °C (2015) and 5.7 °C (2016), and at the Crna Jama 3 site 7.1 °C (2015) and 7.2 (2016), whereas the mean external air temperature was 10.3 °C (2015) and 10.0 °C (2016). In Lepe Jame, the passage most heavily visited by tourists, the mean cave-air temperature is 10.7 °C (2014–2017). Crna Jama exhibits winter and summer temperature regimes. During warm periods (Tcave Tout), ventilation takes place and dense, cold, outside air sinks into Crna Jama because of the favourable cave entrance morphology. Recent Crna Jama air temperature data (2014–2017) indicate a < 0.5 °C higher temperature than that recorded in historical data since 1933. Crna Jama is the most appropriate place within the Postojna Cave System to study long-term climatic changes. There are hardly any tourist visits to the cave, and human impacts on the cave climate are essentially reduced.

Diet comparison between rainforest and cave populations of Craugastor alfredi (Anura: Craugastoridae): does diet vary in contrasting habitats?

ABSTRACTInformation about interpopulational variation of diet is important for thoroughly understanding the ecological niche of a species, the possible attributes that have allowed it to live in different habitats and ecosystems (if it is the case) and the degree of dietary specialization. This study compared dietary composition and diversity, size of prey consumed and feeding intensity between two geographically proximate populations of Craugastor alfredi, inhabiting contrasting habitats: one located in a remnant tropical rainforest and the other population located within a cave entrance, in eastern Mexico. A total of 118 frogs (50 from rainforest and 68 from cave) were stomach-flushed and, from those, 86 had at least one prey item (42 from rainforest and 44 from cave). Consumption proportions of orthopterans differed between habitats, with frogs from the cave having higher importance values of this prey than frogs from the rainforest. Additionally, both dietary diversity and feeding intensity were higher in the rainforest population. It was concluded that the generalized diet of C. alfredi, besides the high consumption of orthopterans by the cave population, may have contributed to its success in cave entrances. Nonetheless, other non-feeding attributes like small body size, direct development and semiarboreality may also facilitate the use of rock crevices in caves for foraging and reproduction.

The impact of door opening on CO2 levels: A case study from the Balcarka Cave (Moravian Karst, Czech Republic)

The impact of door opening on cave carbon dioxide (CO2) levels was studied in the Entrance Chamber and the Gallery Chamber of the Balcarka Cave (Moravian Karst, Czech Republic). The effect of door opening differed with cave ventilation modes. Under upward airflow mode, the cave door opening led to the increase of output advective CO2 fluxes from the cave and to the decrease of CO2 levels. This effect was evident especially in the Entrance Chamber near the cave entrance and then suppressed in the Gallery Chamber situated deeper in the cave. Under the downward airflow mode, the cave door opening changed airflow paths and main CO2 sources/fluxes. This resulted in the increase of CO2 level in the Entrance Chamber while the levels in the Gallery Chamber decrease. Modeling indicates that the increase could be result of input advective CO2 fluxes from epikarst (up to 5.9 × 10-2 mol s-1). To reduce the impact on cave microclimate, a careful control of the visiting regime without overlapping of individual doors’ openings is recommended.