Hemiptera

Many caves in Sicily have been shown to have a sulfuric acid or other hypogenic origin. We studied three caves (Palombara, Scrivilleri, Monello) near Syracuse (eastern Sicily), in an area that was strongly uplifted and faulted, creating multiple Pleistocene marine terraces. Mineralogy, stable isotopes and dating methods (paleomagnetism, U/Th) were used to characterize cave sediments, some of which were related to the initial hypogenic phase (Fe and Mn oxides, calcite spar), others were introduced by surface runoff later. Many other sediments are the result of in situ weathering, such as lime sands produced by condensation-corrosion processes on the calcarenite walls. Phosphates, kaolinite and montmorillonite are related to bat guano decay. Stable isotopes show that the speleothems derive from surface seepage with temperatures similar to the present, with no evidence of a hydrothermal origin. Other deep sources of aggressivity are also excluded. We obtained an age of 603 ka for a marine notch deposit near Palombara, as well as a possible paleomagnetic inversion (>780 ka) for clastic allogenic sediments. These ages are discussed, raising the question of the reliability of calculations extrapolated from marine terrace dating and the possibility that the caves may be older than expected. Cave morphologies clearly indicate a hypogenic phase, with aggressive ascending flows creating the typical Morphologic Suites of Rising Flow (MSRF). The bubble trails and acid notches are formed by carbonic degassing and subsequent acidification in more or less closed aerated environments at the water table. Carbon dioxide probably derived from both the bedrock and the oxidation of surface-derived organic carbon at the density boundaries of the freshwater lens. We propose a mixed Flank Margin Cave and hypogenic speleogenesis model, where dissolution was favored in areas of greater CO2 concentration, producing phreatic maze patterns recording past sea-level positions. We suggest that aggressiveness of the rising fluids could have partly originated at a shallow depth, in the mixing zone between fresh and salt water.

Microphototrophs (algae and cyanobacteria) in karst environments have been intensively studied in aquatic epigean habitats. In recent decades knowledge about the communities inhabiting cave entrances and lampenflora has grown substantially, but the data about the communities in aphotic cave zone are scarce. This study aimed to investigate spatio-temporal presence of microphototrophs in the aphotic zone of Veternica Cave (Mt. Medvednica karst) and to present additional preliminary data from 22 caves of the Dinaric karst. The data were collected over ten years, in parallel with research on cave phagotrophic protists. In addition to the remains of microphototrophs, living algae and cyanobacteria were found in the cave aphotic zone. Diatoms (Bacillariophyta) were the most frequent group found, followed by green algae (Chlorophyta), golden-brown algae (Chrysophyta) and the filamentous cyanobacteria (Cyanobacteria). The presence of microphototrophs was detected throughout the year but showed spatio-temporal variations. Microphototrophs were absent in the parts of Veternica Cave with seeping and dripping water, while they were occasionally present in the hydrologically active parts of the cave. The presence of diatoms in the aphotic zone of Veternica Cave was related to hydrological conditions, and was not affected by the distance from the cave entrance. The presence of microphototrophs in caves of the Dinaric karst has been associated with caves subject to various types of flooding by endogenous and exogenous water. Despite the fact that microphototrophs are passively transported to the caves from the surface habitats, the presence of live individuals in the cave aphotic zone implies that they should not be neglected in discussions about cave food webs. Future research of microphototrophs should be focused on the species identification, their abundance, survival time, and detail description of conditions that determine their presence in caves.

Recent research on air pressure propagation through barometric caves has revealed various speleoclimatological processes, which cause a more complex relationship between surface air pressure changes and resulting pressure gradients between cave and surface air than previously assumed. So far, however, studies on barometric cave airflow have only been based on surface air pressure measurements. Thus, this study investigates and compares airflow at the openings of Wind Cave and Jewel Cave – two major barometric cave systems in South Dakota, USA – as a response to surface air pressure changes and air pressure gradients. Based on high-resolution long-term air pressure measurements from the surfaces and several locations inside the caves, as well as ultra-sonic airflow measurements at the openings, the analysis proves that for both caves, cave airflow velocity can be predicted more accurately by air pressure gradients than by previous surface air pressure changes. An inter-cave comparison also reveals substantial differences in cave airflow dynamics between Wind Cave and Jewel Cave, with the relevant period of surface air pressure variations for cave airflow velocity and the cave reaction times being significantly longer at Jewel Cave compared to Wind Cave. Therefore, the findings of this study demonstrate the effects of cave morphology on airflow and significantly contribute to a better understanding of the speleoclimatological mechanisms and dynamics of compensating airflow at the openings of barometric caves.

The cave’s physical environment can be affected by tourism activities but only a few studies evaluated how recreational use may affect the cave fauna, mainly in caves with a low number of visitors per year. To test the hypothesis that recreational use led to changes in habitat structure and invertebrate diversity, distinct scales along a cave were analyzed. Distinct areas with and without human visitation were analyzed and transects (10 x 3 m) and quadrats (1 x 1 m) were used to access the invertebrate communities and environmental traits. Thirty-two invertebrate species were recorded, among which six are troglobitic. The similarity of non- troglobitic species differed between the visited and non-visited areas. Substrate composition inside transects differed between the two areas and the differences were higher in the percentage of matrix rock and fine sediments. The distance from the entrance influenced the similarity of non-troglobitic species while troglobitic fauna responded to the proportion of sandy sediment. Inside quadrats, both matrix rock and fine sediments influenced the similarity of non-troglobitic species. Similarity of non-troglobitic species in the visited area was explained by the proportion of matrix rock in transects and quadrats. The proportion of cobbles influenced the similarity of non-troglobitic species in quadrats in the non-visited area. The non-troglobitic species richness inside quadrants was positively related to the amount of guano, wood, fine sediment, boulders, cobbles, matrix rock, sand sediment, and plant debris. Differentiation in habitat structure and faunal composition between the two areas seems to be an effect of distance from the entrance and spatial heterogeneity, but not recreational activities.

The Camou springs (Arbailles Massif, French Western Pyrenees) display an unusual close association of a typically cold karstic spring that drains the Urgonian western limb of the Arbailles, and a thermo-mineral spring (33.5°C; salinity 17.7 g/L). The latter gains its mineralization at the contact of Triassic evaporites mainly through a deep loop in the Apanicé syncline. The fast upflow of this deep water occurs at the cross of large active lines (the North-Pyrenean thrust located at depth, and the Saison transverse fault). Cave diving in the nearby Maddalen Cave allowed reaching the phreatic passage at the origin of the cold spring, which however also crosses the thermal body in the third sump (S3). Both water bodies are separated by a sharp thermocline. 6 pressure-temperature dataloggers were placed in both water bodies along the thermocline for 6 months. The dataloggers located downstream on either side of the thermocline show at the beginning of flood first a rise of the thermal body, then an invasion of the whole phreatic passage by the cold floodwater, controlled by head pressure changes in the karst aquifer. From observation of these mechanisms, we deduce a hydrodynamic model with a warm plume rising into the cold aquifer, without significant mixing. Such independence of water bodies is explained by the decrease of turbulent rate at the interface, due to the sharp density gradient. The relative absence of mixing does not actually require independent “watertight” routes, both water bodies can thus coexist even in the same conduit. This model locally implies the existence of unknown secondary passages close to the spring, which allow an independent draining of each water body toward separate outlets during low stage. Such type of stratified aquifer linked to density differences is common in coastal karst (Florida, French Calanques…), in the continental evaporite karst (Schlotten of the Harz in Germany, Kungur karst in Ural…), but remains poorly identified in continental carbonate karst areas, mainly because of the difficulty of access. Together with the Mescla spring in French Alpes-Maritimes, the Camou twin springs discharging in the same porch are an outstanding example, allowing a direct study of the stratification and the dynamic of highly contrasted water bodies.

Waitomo Glowworm Cave is a highly visited cave where the highlight is viewing the bioluminescence display of a large colony of glowworms. The visitation levels result in the build-up of anthropogenic CO2, to the extent that it could cause corrosion of speleothems. The cave experiences chimney-effect ventilation with air flowing either upward or downward through the main cave chambers depending on air density differences between the cave and the outside environment. Lack of airflow leads to CO2 build-up; however, unrestricted airflow can draw in cool, dry air which is harmful to the glowworms. Consequently, airflow is managed by controlling the opening and closing of a door that seals the upper-most entrance, preventing ventilation under drying conditions and promoting ventilation when it is necessary to clear CO2 and when inflowing air has high relative humidity. A network of microclimate sensors in the cave allows prediction and management of the ventilation pattern. Management leads to asymmetric airflow through the year, which has a flow-on effect on cave temperature. Microclimate monitoring supports the current management practices that use door control to enhance cave ventilation when people are in the cave. Suppressing airflow, especially in winter, reduces the introduction of dry air.

The Ochtiná Aragonite Cave (Western Carpathians) represents an unique natural phenomenon. It originated under particular lithological and hydrogeological conditions of the Ochtiná Karst in which several isolated lenses of Paleozoic crystalline limestone (marbles), partly metasomatically altered to ankerite, are enclosed by phyllites. Meteoric water seepage through non-carbonate rocks dissolved limestone and caused the oxidation of ankerite to Fe oxyhydroxides. Carbon dioxide produced during ankerite oxidation enhanced limestone dissolution. The maze cave consists of parallel fault-controlled linear passages and chambers interconnected by transverse horizontal passages. Phreatic and epiphreatic solution morphologies resulted from slowly moving or standing water. These include flat ceilings (Laugdecken), facets (planes of repose, Facetten), lateral notches, convection ceiling cupola-shaped depressions, and spongework-like hollows. Flat ceilings were developed in several altitude positions, each of them probably closely below the slightly oscillated water table. Primary phreatic cupola-shaped depressions, truncated by flat ceilings, represent relics of the oldest cavities (pre-Quaternary? to Early Pleistocene). Inward-sloping smooth facets were not developed only in passages with flat ceilings, but also in the passages and halls with a vaulted ceiling. The asymmetrical shape of cusped depressions above the facets were documented in detail by a high-resolution cave topography with terrestrial laser scanning and digital photogrammetry. Middle–Late Pleistocene accumulation phases, identified by magnetostratigraphy of cave sediments and U-series dating of speleothems, are associated with phreatic and later epiphreatic development. The deposition on the bottom bedrock began before 1.8 Ma. The Brunhes/Matuyama boundary (0.773 Ma) and Jaramillo magnetozone (0.990–1.071 Ma) were recorded in the profile in the Oválna chodba Passage. Slow depositional rate (~0.09 cm/kyr) calculated from magnetostratigraphy resulted from slow water movement in confined conditions in marbles completely enclosed by phyllites and no direct relation to the surface. Only occasionally turbid water was loaded in extremely fine-grained infiltration material and autochthonous Fe oxyhydroxides. The depositional rate in Mn-rich layer was much slower (~0.03 cm/kyr). Additional U-series dating confirmed that old aragonite generations (with ages about 500–450 ka and 143–121 ka) were partly corroded by repeated floods during Late Pleistocene humid episodes. Aragonite younger than 13.5 ka is not corroded.

Based on the morpho-genetic study of stygobiotic shrimps from the genus Xiphocaridinella Sadowsky, 1930 (Crustacea: Decapoda: Atyidae), a hydrogeological connection of a number of distant caves in Central Abkhazia of the southwestern Caucasus is satisfied, which indicates the possibility of using biospeleological studies in some cases to identify karst hydrosystems together with traditional hydrogeological methods. Moreover, a new stygobiotic atyid shrimp from the genus Xiphocaridinella, X. kelasuri sp. n., is described based on morphology and analysis of mitochondrial cytochrome oxidase I DNA sequences from three distant caves. The new species is genetically divergent from relatives and phylogenetically related to Xiphocaridinella smirnovi Marin, 2020, described from the Besletka (=Tskaro) Cave. Recently, the number of described speciesof the genus Xiphocaridinella from Caucasus has increased to 13 species, while the diversity of Xiphocaridinella found in the Besletka (=Tskaro) Cave is increasing to 3 species, which is higher than in any other known cave where Troglocaris-like shrimps have been discovered.

Density-driven chimney effect airflow is the most common form of cave ventilation, allowing gas exchange between the outside and the karst subsurface. However, cave ventilation can also be driven by other mechanisms, such as barometric changes or pressure differences induced by the outside winds. We discuss the mechanism and dynamics of wind-driven ventilation using observations in Postojna Cave, Slovenia. We show how seasonal airflow patterns driven by the chimney effect are substantially modified by outside winds. Wind flow over irregular topography forms near-surface air pressure variations and thus pressure differences between cave entrances at different locations. These pressure differences depend on wind speed and direction and their relationship to surface topography and the location of cave entrances. Winds can act in the same or opposite direction as the chimney effect and can either enhance, diminish or even reverse the direction of the density-driven airflows. To examine the possibility of wind-driven flow, we used a computational fluid dynamics model to calculate the wind pressure field over Postojna Cave and the pressure differences between selected points for different configurations of wind speed and direction. We compared these values with those obtained from airflow measurements in the cave and from simple theoretical considerations. Despite the simplicity of the approach and the complexity of the cave system, the comparisons showed satisfactory agreement. This allowed a more general assessment of the relative importance of wind pressure for subsurface ventilation. We are certain that this example is not unique and that the wind-driven effect needs to be considered elsewhere to provide better insights into the dynamics of cave climate, air composition or dripwater geochemistry.

Vermiculations are aggregates of small particles commonly found on cave walls. They are a major concern for the conservation of painted caves, as they can potentially alter valuable prehistoric cave paintings. A previous rheological study of fine sediment deposits on cave walls revealed that this material can undergo a solid-to-liquid transition triggered by variations in the chemical composition of the water film on the wall. Such a transition could occur at the origin of vermiculations by allowing the sediment to flow under low mechanical stress. In this work, we provide quantitative information on the conditions leading to this transition and show the importance of the chemical composition of the water film on the cave walls. A complete understanding of the phenomenon will, however, require more field information. This includes monitoring of the evolution of vermiculations, for which we have developed a dedicated observation protocol. Based on the combination of photogrammetry and a geographic information system we were able to precisely map the walls of the Hall of Bulls in Lascaux cave from past and future photographs. To better understand the vermiculation process, pictures need to be taken regularly, and the chemical composition of the thin water film covering cave walls needs to be analyzed with a similar time step. The correlation between the evolution of vermiculations, the humidification phases of the walls, temperature changes and the chemical monitoring of the water film should shed new light on conditions triggering vermiculations.

Some recent publications on the paleo- and historical environmental interpretation of bat guano sequences have relied on 210Pb and 137Cs distribution to establish age-depth models, even when these are at odds with radiocarbon models in the lower parts of the sequence. Here, we present both field and laboratory evidence for the unpredictable mobility of lead and cesium in decomposing bat guano deposits. We suggest that 210Pb- and 137Cs-based chronologies of bat guano deposits should only be used when independently supported, for example, by a robust radiocarbon age-depth model.

In the last decade, the scientific community brought to the debate gaps that slow down the advance of knowledge regarding global biodiversity. More recently, this discussion has reached subterranean environments, where these gaps are even more dramatic due to the relict and vulnerable nature of their species. In this context, we tested ecological metrics related to some of these gaps, checking if the biological relevance of the caves would change depending on ecological attributes related to each metric. The study was carried out in caves from southeastern Brazil, located in a region presenting a high richness of troglobitic species restricted to a narrow geographical extent. Thus, we verified: (a) the cave invertebrate communities’ vulnerability with the Vulnerability Index and the Importance Value for Cave Conservation; (b) the distribution and endemicity of the troglobitic species with the Endemicity Index; (c) the phylogenetic diversity of the troglobitic species considering the average taxonomic distinction (∆+), their richness and evenness. We observed a considerable change in the ordering of the caves’ biological relevance according to each tested attribute (index). We discussed how each of these metrics and their attributes indirectly relate to: (a) the preservation and maintenance of the phylogenetic diversity of subterranean communities; (b) the spatial restrictions of different groups, where the greater their restrictions, the greater their vulnerability; (c) the preservation of caves with high biological relevance considering these different attributes together. Thus, we recommend the use of different metrics so that different ecological attributes can be considered, supporting actions that aim to preserve caves in highly altered regions. Finally, we find that the most biologically important cave in the region is not protected (Gruta da Morena cave). We warn that this cave needs to be contemplated by a conservation unit in the region urgently.

Recently, several new species and subspecies from the genus Eremogryllodes Chopard, 1929 (Insecta: Orthoptera: Myrmecophilidae) inhabiting caves of Iran, have been described based on morphology. The high variation of genitalia structure along with high similarity of external morphology between populations hamper the precise species identification. Thus, molecular approaches are critical to determine the taxonomic positions of species/subspecies of this genus. Here we provide the molecular phylogeny, based on the 16S rRNA mitochondrial gene, of recently described species of Eremogryllodes along with some unidentified specimens from the same region. The results support the monophyly of the family Myrmecophilidae. The topology of the 16S rRNA tree did not completely support the five morpho-species. The three main recovered clades mainly grouped specimens by their geographical locations. Our study suggests the possibility of more than one species in one cave and the presence of cryptic species among cave dwelling crickets, based on the 16S rRNA marker.

Here we addressed the question of whether burning of guano produces a characteristic suite of morphological changes and/or unique mineralogical products. The changes observed in our experimental burning of guano (both fresh and decayed) included colour change (blackening), grain size and morphological change (grain size generally reduced, morphology rendered generally less distinct), alteration of minerals by dehydration (e.g., gypsum to anhydrite, brushite to whitlockite), and production of new minerals or compounds (e.g., augelite, bayerite, giniite, graphite, oldhamite, strontium apatite, tridymite). The key morphological feature we found that may be diagnostic of burning was severe damage to crystals from rapid dehydration (cracks and striations, leading to eventual fragmentation). The key mineralogical feature we found was production of graphite. The high temperature exotic minerals that were produced (giniite, augelite, tridymite, oldhamite) were all found not to be high temperature obligate. Evidence gleaned from the literature suggests that a great number of the minerals associated with high temperatures can also be synthesized in low temperature settings such as weathering or microbial action (exemplified in the extremely complex biology and biochemistry of decaying guano). While the presence of any one of these minerals is not diagnostic of fire, it could be argued that the suite taken as a whole is moderately strong evidence for burning. In future studies, the chemistry of carbon aromaticity may prove to be the best diagnostic test for pyrolysis. A survey of the conditions under which documented spontaneous ignition occurs leads us to conclude that spontaneous ignition of guano inside a cave is an extremely unlikely event, and any suggestion/assertion to this effect should be rigorously supported.

This article details the analysed results of the recent study on heleomyzid flies (Diptera: Heleomyzidae) that occurred in the caves of Kraków-Częstochowa Upland. Additionally, all accessible information about those flies from the Polish caves has been compiled. In effect, 23 species from seven genera were identified. Among these determined species, one was considered as troglobiont, eleven as eutroglophiles, nine as subtroglophiles, and two as trogloxenes. Dominant species were Scoliocentra brachypterna, Heleomyza captiosa and Eccoptomera pallescens. The highest number of species has currently been found in the Kraków-Częstochowa Upland.