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Climate change going deep: The effects of global climatic alterations on cave ecosystems
Abstract
Scientists of different disciplines have recognized the valuable role of terrestrial caves as ideal natural laboratories in which to study multiple eco-evolutionary processes, from genes to ecosystems. Because caves and other subterranean habitats are semi-closed systems characterized by a remarkable thermal stability, they should also represent insightful systems for understanding the effects of climate change on biodiversity in situ. Whilst a number of recent advances have demonstrated how promising this fast-moving field of research could be, a lack of synthesis is possibly holding back the adoption of caves as standard models for the study of the recent climatic alteration. By linking literature focusing on physics, geology, biology and ecology, we illustrate the rationale supporting the use of subterranean habitats as laboratories for studies of global change biology. We initially discuss the direct relationship between external and internal temperature, the stability of the subterranean climate and the dynamics of its alteration in an anthropogenic climate change perspective. Owing to their evolution in a stable environment, subterranean species are expected to exhibit low tolerance to climatic perturbations and could theoretically cope with such changes only by shifting their distributional range or by adapting to the new environmental conditions. However, they should have more obstacles to overcome than surface species in such shifts, and therefore could be more prone to local extinction. In the face of rapid climate change, subterranean habitats can be seen as refugia for some surface species, but at the same time they may turn into dead-end traps for some of their current obligate inhabitants. Together with other species living in confined habitats, we argue that subterranean species are particularly sensitive to climate change, and we stress the urgent need for future research, monitoring programs and conservation measures.
... Global ecological effects of climate have been analyzed in many ecosystems, for example, in arctic (Post et al. 2019), tropical (Artaxo et al. 2022), and marine (Cheng et al. 2022) environments. Lately, the interest of scientists is focusing on subterranean habitats that are considered model systems to better understand the effects of climate change on ecosystems (e.g., Mammola 2019; Mammola et al. 2019a;Wynne et al. 2021). In general, subterranean environments show reduced levels of seasonal and annual variation, not only in their physical parameters, such as light intensity, air temperature, and relative humidity, but also in their biotic energy inputs derived from external organic subsidies Pipan 2009, 2014). ...
... Values above 0.5 indicate a male-biased sex ratio. capacity of the surrounding geological substrate that causes a phenomenon called thermal inertia, a delay in the equilibration between the temperature of the atmosphere and the geological substrate of the subterranean cavity (Badino 2004;Mammola et al. 2019a). This time delay depends on different factors, such as the thickness (Domı nguez- Villar et al. 2015) and the geological nature of the rocks embedding the subterranean cavity (Medina et al. 2023). ...
... This time delay depends on different factors, such as the thickness (Domı nguez- Villar et al. 2015) and the geological nature of the rocks embedding the subterranean cavity (Medina et al. 2023). Notably, even if a direct correlation between subterranean and surface temperatures has been described (Badino 2004), the thermal inertia may delay changes in temperatures for years or even decades (Mammola et al. 2019a). In fact, in a Slovenian cave hall at approximately 37 m from the surface, temperatures could display a delay of 20-25 yr according to the model of Domı nguez-Villar et al. (2015). ...
Long-term effects of current climate on animal populations living in subterranean habitats are still poorly understood. In this study, we analyzed the variability of the demographic structure and abundance of a population of terrestrial plethodontid Strinati's Cave Salamanders (Speleomantes strinatii) (Aellen, 1958) living inside a northwestern Italian artificial cave over 27 yr from 1996 to 2022. The study site is situated in the Northern Apennines, where average air temperatures measured at two local weather stations were steadily increasing, whereas precipitation was relatively constant over the past 60 yr. Our objective was to evaluate whether the demographic traits of the population of Strinati's Cave Salamanders were showing detectable signs of directional shift during the 27 yr. Each year in July, the population abundance was estimated by a three-occasion removal experiment, salamanders' snout-vent length (SVL) was measured, and the population polymodal body-size distribution was decomposed into estimated age classes. The annual population abundance, adult sex ratio, recruitment, SVL, and growth increments of first-and second-year immature salamanders were analyzed. The Strinati's Cave Salamander time series was modeled by autoregressive moving average (ARMA) analysis, and demographic parameters were tested for temporal trends. There were no directional trends observed in any of the demographic parameters of the focal cave salamander population over the study period. The best autoregressive model describing the population variation was an ARMA (2,1). Results indicated that the salamander population had a complex fluctuating pattern in which the interaction of lagged density dependence and an external autocorrelated factor were influencing the population long-term dynamics. Our findings suggest that the population of this long-lived salamander species was probably buffered from external conditions by the thermal inertia of its subterranean habitat that is known to delay and reduce the amplitude of aboveground climatic signals.
... Global ecological effects of climate have been analyzed in many ecosystems, for example, in arctic (Post et al. 2019), tropical (Artaxo et al. 2022), and marine (Cheng et al. 2022) environments. Lately, the interest of scientists is focusing on subterranean habitats that are considered model systems to better understand the effects of climate change on ecosystems (e.g., Mammola 2019; Mammola et al. 2019a;Wynne et al. 2021). In general, subterranean environments show reduced levels of seasonal and annual variation, not only in their physical parameters, such as light intensity, air temperature, and relative humidity, but also in their biotic energy inputs derived from external organic subsidies Pipan 2009, 2014). ...
... Values above 0.5 indicate a male-biased sex ratio. capacity of the surrounding geological substrate that causes a phenomenon called thermal inertia, a delay in the equilibration between the temperature of the atmosphere and the geological substrate of the subterranean cavity (Badino 2004;Mammola et al. 2019a). This time delay depends on different factors, such as the thickness (Domı nguez- Villar et al. 2015) and the geological nature of the rocks embedding the subterranean cavity (Medina et al. 2023). ...
... This time delay depends on different factors, such as the thickness (Domı nguez- Villar et al. 2015) and the geological nature of the rocks embedding the subterranean cavity (Medina et al. 2023). Notably, even if a direct correlation between subterranean and surface temperatures has been described (Badino 2004), the thermal inertia may delay changes in temperatures for years or even decades (Mammola et al. 2019a). In fact, in a Slovenian cave hall at approximately 37 m from the surface, temperatures could display a delay of 20-25 yr according to the model of Domı nguez-Villar et al. (2015). ...
... De hecho, aunque se trata de sistemas en general muy aislados e inaccesibles, el medio subterráneo no está desvinculado de los impactos que afectan a otros ecosistemas en la superficie ni de los efectos del cambio climático. Precisamente por el alto grado de especialización de su fauna, ante un aumento rápido de la temperatura y un cambio en las condiciones climáticas, los hábitats subterráneos pueden convertirse en trampas sin salida para algunas de las especies que actualmente viven allí de forma obligada, pero también pueden actuar como refugios para algunas especies de la superficie, lo que daría lugar a importantes modificaciones de las interacciones bióticas en el subsuelo (Mammola et al. 2019b;Nicolosi et al. 2023). ...
... A pesar de la importancia de estudiar los efectos del cambio climático en el medio subterráneo y de las ventajas que este medio ofrece para ello (Sánchez-Fernández et al. 2018;Mammola et al. 2019b), este trabajo muestra que en la península ibérica se le ha empezado a prestar atención a este tema en los últimos 12 años. Además, esta revisión localiza importantes carencias en nuestro conocimiento sobre los efectos del cambio climático en la biodiversidad subterránea ibérica y propone una serie de líneas prioritarias en las que se debería trabajar en los próximos años. ...
... La valiosa información proporcionada por los estudios de tolerancia térmica podría refinarse aún más teniendo en cuenta otros factores, como humedad, salinidad, contaminantes, etc., y sus posibles interacciones con un aumento de temperatura. Especialmente relevante podría ser el estudio del efecto de la humedad, cuyos altos valores en el medio subterráneo (en el punto de saturación o muy próximo al mismo) parecen ser esenciales para la supervivencia de los organismos troglobiontes (Mammola et al. 2019b). Howarth (1980) sugirió que los invertebrados subterráneos tienen una alta permeabilidad cuticular, asociada con una resistencia muy baja a la desecación, lo cual ha sido demostrado empíricamente en algunas especies (Ahearn y Howarth 1982;Yoder et al. 2011). ...
Datos recopilados en los artículos examinados sobre la región de estudio, especies estudiadas (información taxonómica y especificidad por el medio subterráneo), metodología y resultados. Los resultados cuantitativos se muestran como un único valor (ej.: temperatura letal), como una tasa de cambio porcentual entre dos tratamientos de temperatura (%/ºC) o entre dos escenarios climáticos (presente/futuro).
... According to this definition, caves are only a small fraction of the total habitat available to subterranean insects; yet, there is still a significant research bias towards these human-accessible habitats, which should always be kept in mind when thinking about our current understanding of threats and conservation issues . physiological and behavioural plasticities to withstand environmental perturbations (Mammola et al. 2019b, Castaño-Sánchez et al. 2020. For example, given that daily and seasonal variations in subterranean temperatures are much smaller compared to the surface ( Figure 24.2), ...
... Global climate change is another important threat that, predictably, will affect subterranean ecosystems indiscriminately (Mammola et al. 2019b). Yet, experts perceive the impact of climate change underground as less severe than that of other direct threats discussed in the previous section (Figure 24.3A). ...
... While a great deal of attention has been paid to the most specialised species, which may undergo local extinctions due to climate change, there are less specialised animals potentially able to respond with dispersal to climatic alterations. Movements of faunas from surface to subterranean habitats are also to be expected (Mammola et al. 2019b). For example, soil-and surface-dwelling insects may exploit superficial subterranean environments, especially cave entrances and other shallow subterranean voids, as climate refuges with buffered climatic extremes (Ledesma et al. 2020;Moog et al. 2021). ...
This chapter addresses the multiple threats faced by subterranean insects and their conservation. Subterranean insects are intrinsically vulnerable to anthropogenic threats due to their small distribution ranges, small population size, restricted habitat, and limited physiological and behavioural plasticities. Although we lack a quantitative understanding of population trends and long-term series of data, experts agree that habitat modification at the surface and climate changes are the most pervasive threats that may negatively affect subterranean insects. Beyond acquiring basic knowledge about subterranean insects and establishing monitoring programmes, their future conservation will be best achieved by (i) expanding protected areas’ coverage of global hotspot of subterranean diversity; and (ii) increasing awareness about subterranean insects and the important nature’s contribution they provide to people.
... For example, within the Indo-Malayan region, average temperatures in areas such as the central Himalayas have increased significantly more than the global average (Shrestha et al., 2012;Mayewski et al., 2020), with fluctuations more pronounced at higher elevations (Bhutiyani et al., 2007). As cave temperatures are directly correlated with surface-level temperatures, cave emergence behaviors may change in response to climate warming (Badino, 2004;Mammola et al., 2019a). These changes are ecologically significant, as shifts in emergence timing could be energetically costly for bats when food is scarce and could ultimately impact the food web within cave ecosystems (Phelps et al., 2016;Frick et al., 2020;Meierhofer et al., 2024). ...
... Such shifts when modeled with a combination of fine-scaled cave microclimatic data, bat morphological and physiological data and broad-scaled landscape level data can help predict species-specific vulnerabilities and future responses of bats to climate change (Kearney et al., 2021). These modeling approaches will be more convenient in the context of the central Himalayas because caves, as a refuge, are at risk of undergoing temperature changes, given their high correlation with air temperatures (Badino, 2004;Mammola et al., 2019a;McClure et al., 2020;Medina et al., 2023). ...
Bats spend a significant portion of their time roosting inside caves, where they can enter daily torpor or hibernation as an energy-saving strategy. Between torpor bouts, bats may awaken and emerge to rehydrate, forage, or switch roosts. Such activities are closely linked to species-specific responses that are triggered by changes in surface-level temperatures. Climate warming can, thus, alter bat emergence behaviors, with potentially more pronounced effects in regions like the central Himalayas, where climate warming exceeds the global average. However, emergence patterns from cave systems in this region are understudied, with limited information available to monitor future changes in such behaviors. To address this gap, we examined an elevational gradient across three different seasonal phases to quantify variations in cave emergence activity in the central Himalayas. A total of 23 caves were surveyed using acoustic monitors along an elevational gradient (400–2700 m) during mid-winter, late winter, and early spring. Overall, bat emergence activity was significantly greater in late winter and early spring compared to mid-winter. During mid-winter, activity was only observed in caves in the lower elevation. In late winter and early spring, emergence activity increased across all elevations, although activity levels varied between species. These findings provide a baseline for long-term monitoring of bat emergence activity in the central Himalayas as winters continue to warm due to climate change.
... En primer lugar, la temperatura media del interior de la cueva (entre 4,6 y 4,9 ºC) y la estimada para la altitud de la entrada de la cueva (4,9 ºC) son muy similares. Este hecho ha sido señalado previamente en trabajos sobre temperaturas de cuevas (Davies, 1960;Moore, 1964;Moore y Nicholas, 1964;Domínguez-Villar et al., 2013;Mammola et al., 2019), y es debido a que el aire penetra en las cuevas desde el exterior y se transfiere por conducción a través de la cueva (Domínguez-Villar et al., 2013) en función del desequilibrio térmico con el exterior (Freitas et al., 1982), tendiendo a alcanzar una temperatura constante por el aumento de la hu- medad relativa y el equilibro con la temperatura de la roca (Wigley y Brown, 1971;1976). De hecho, Domínguez-Villar y otros (2013) señalaron que los cambios en la cubierta vegetal del entorno de la entrada de la cueva pueden afectar a la temperatura de la misma, lo que tiene implicaciones en el desarrollo de los espeleotemas. ...
... En este lugar se han registrado temperaturas de entre 19 ºC y 2 ºC, con una marcada oscilación térmica que está relacionada con las temperaturas del exterior de la cueva. Esta relación entre el interior y el exterior nos indica que se trata de una zona altamente ventilada (Mammola et al., 2019), en la que se da una convección forzada debido a la diferencia de temperatura entre el interior y exterior de la cueva, lo que impulsa el intercambio de calor entre ambos ambientes y explica las oscilaciones térmicas en la entrada de las cuevas (Luetscher et al., 2008). ...
En este artículo se presentan los datos de temperatura y humedad obtenidos entre 2018 y 2020 a diferentes profundidades (entrada, -350 m, -450 m y -680 m) en la cavidad de Torca Marino (Parque Nacional de los Picos de Europa, León) que, con un desnivel de -943 m, es una de las de mayor desarrollo vertical del mundo. Los datos muestran una temperatura interior de 4,6 ºC a -350 m, entre 4,7 y 5,1 ºC a -450 m y de 4,8 ºC a -680 m, con un ambiente siempre saturado y condiciones homotérmicas, aunque con pequeñas fluctuaciones de hasta 0,4 ºC en el sector de la Gran Mulata, con un gradiente de temperatura muy bajo (0,06 ºC cada 100 m) entre las distintas profundidades. Estos valores son muy semejantes a la temperatura media a la cota de entrada a la cueva, estimada en 4,9 ºC. El paso de los espeleólogos también tuvo repercusión en las temperaturas registradas, que ascendieron hasta 0,5 ºC para volver a sus valores normales. El ambiente saturado ha favorecido el desarrollo de espeleotemas, aunque concentrados únicamente en las galerías horizontales, separadas por grandes conductos verticales. Helictitas, frostworks, coralloids, micro-chimeneas de hadas, pisolitas y agregados columnares son los principales espeleotemas de pequeño tamaño localizados en el interior de la cavidad, destacando su notable desarrollo y, sobre todo, su excelente estado de conservación. En el caso de las micro-chimeneas de hadas, no se han encontrado citas previas en el interior de cavidades.
... First, external climate is intimately connected with the inner microclimatic conditions of subterranean environments, where it mostly affects the areas close to the entrance (Badino 2004;Lunghi, Manenti, and Ficetola 2015;Culver and Pipan 2019). Thus, the increase of temperature and dryness at the surface caused by global warming will also be replicated in the shallowest areas of subterranean environments (Mammola et al. 2019), reducing the availability of suitable habitats and therefore representing a threat to many cave-dwelling species (Rizzo et al. 2015;Sánchez-Fernández et al. 2016;Mammola, Goodacre, and Isaia 2018). Secondly, as facultative cave-dwellers (so-called troglophiles; Howarth and Moldovan 2018), Speleomantes often forage on the surface, where prey is more abundant Culver and Pipan 2019). ...
... Indeed, individuals probably will not disperse fast enough to reach new future suitable areas, thus remaining trapped in their subterranean refugia. Here, climate change will progressively confine them to the deepest oligotrophic areas where trophic supply is probably insufficient for the sustainment of the entire population Culver and Pipan 2019;Mammola et al. 2019). Additionally, natural barriers may play an important role in limiting Speleomantes dispersal. ...
Aim: Amphibians are particularly sensitive to rapid climatic shifts, due to their eco-physiology, life history traits and high frequency of narrowly distributed species. The genus Speleomantes encompasses the only extant Western Palearctic plethodontids, with three species occurring in peninsular Italy and the remaining five endemic to Sardinia Island. Given the restricted ranges of Speleomantes species and their vulnerability to environmental change, we implemented Ecological Niche Models (ENMs) to estimate the likely impacts of various global warming scenarios on the extent and geographical location of climatically suitable areas.
Time Period: Current, with ENMs projected to 2030, 2050 and 2070 under alternative Shared Socioeconomic Pathways.
Location: Italian Peninsula and Sardinia Island.
Major Taxa Studied: Speleomantes Dubois 1984 (Caudata: Plethodontidae).
Methods: Ensembles of ENMs were fitted for each Speleomantes species, using the 'biomod2' modelling platform in R environment. Then, post-modelling analyses were applied in GIS environment to highlight: (i) the primary geographic direction of predicted suitability shifts for each species and (ii) the proportion of stable, gained and lost suitable areas for each genetic lineage of the single species.
Results: We found a noticeable shrinking of suitable areas for all Speleomantes species, being particularly extensive under 'business-as-usual' scenarios for the Sardinian ones. Moreover, core suitable areas were predicted to shift for most species and suitability losses emerged to differently affect distinct genetic lineages, posing additional challenges for designing effective conservation measures.
Main Conclusions: The predicted shrinkage and shifting of climatically suitable areas for most Speleomantes species point to the urgency of evaluating in due time alternative conservation strategies for these endemic urodeles, to prevent losses of taxonomic and genetic diversity. Our modelling framework may be applied to other species with similar traits (e.g., low dispersal ability and narrow environmental niche breadth) to predict climate-induced range contractions or shifts, using the gained information to optimise conservation outcomes.
... Mammuthöhle [17] , Hundsalm Eis-und Tropfsteinhöhle [18] and Obstanser Eishöhle [19] . Warming of underground cavities has been shown to have also signi cant consequences for subterranean biota and ecosystems [20,21] . ...
... The values of air temperature averaged over time between the stake readings (black line) show a transition from initially negative values towards mostly positive values. This analysis con rms a strong physical relationship between long-term temperature evolution and the development of ice in caves, as is known from ice caves elsewhere [29,18,19,30] . ...
Cave air temperatures in four caves in the European Alps show statistically significant warming trends of about 0.2 °C per decade over the last two decades (2000-2020). These trends are about half as large as those observed outside and are characterized by a remarkable spatial and temporal consistency. The investigated caves represent different types in terms of their ventilation regime and one of them also hosts perennial ice. Key observation sites are located in cave sections where the temporal variability of air temperature is strongly attenuated compared to outside conditions and data from different cave sections show that the main results are valid for large parts of the investigated caves.
Continued warming will lead to broad changes in Alpine cave environments, including changes in the ventilation regime, karst hydrology and subsurface ecosystems. The observed subsurface warming has a particular strong effect on the long-term preservation of perennial ice present in some of these caves. This is shown for an ice cave in the Austrian Alps, where enhanced melt of ice correlates with the observed warming. This cave (and similar ones) will not be able to hold perennial ice beyond the next decade.
... Furthermore, human visitation of subterranean systems, whether for scientific and caving activities or mass tourism in show caves, causes local impacts such as trampling, disturbance to the fauna, alterations to local climatic conditions, and introduction of organic materials, non-native invasive species, and pathogens [91][92][93][94] . Finally, the combination of these regional impacts with global climate change might result in additive, synergistic, or antagonistic effects 95 . While the specifics remain debated, a recent meta-analysis linked multiple biological effects to climate change, with varying magnitudes depending on the type of subterranean habitats and ecological specialization of taxa 96 . ...
... A first, indirect approach relies on the protection of large buffering areas at the surface to preserve subterranean habitats underneath and maintain essential ecological processes. This stems from the understanding that subterranean biodiversity is strongly affected by above-ground processes (e.g., recharge events through rainfall 112,113 , land-use change 114 , climate change 95,96 ), and that alterations at the surface can trickle down and impact the subterranean levels (Box 1). For this "buffering" approach to work effectively, it is important to test the extent to which surfaceprotected areas benefit the ecosystems underneath 10,115 . ...
Subterranean ecosystems (comprising terrestrial, semi-aquatic, and aquatic components) are increasingly threatened by human activities; however, the current network of surface-protected areas is inadequate to safeguard subterranean biodiversity. Establishing protected areas for subterranean ecosystems is challenging. First, there are technical obstacles in mapping threedimensional ecosystems with uncertain boundaries. Second, the rarity and endemism of subterranean organisms, combined with a scarcity of taxonomists, delays the accumulation of essential biodiversity knowledge. Third, establishing agreements to preserve subterranean ecosystems requires collaboration among multiple actors with often competing interests. This perspective addresses the challenges of preserving subterranean biodiversity through protected areas. Even in the face of uncertainties, we suggest it is both timely and critical to assess general criteria for subterranean biodiversity protection and implement them based on precautionary principles. To this end, we examine the current status of European protected areas and discuss solutions to improve their coverage of subterranean ecosystems.
... However, despite the significance of these studies, substantial knowledge gaps persist in the ecology of subterranean habitats (Culver et al., 2004;Culver et al. 2008;Lunghi & Manenti, 2020). The inherent complexity of subterranean research, coupled with challenges like inaccessibility and the difficulty of directly observing these communities, represents barriers that prevent comprehensive scientific inquiry (Ficetola et al., 2019;Mammola et al., 2019). ...
Subterranean ecosystems remain among the least explored on the planet, although studies have unveiled their biodiversity
and potential for research across various ecological domains. Historically, the European continent pioneered research and
knowledge production in this field. However, interest in the topic has been growing on other continents, particularly in recent
decades. To understand historical trends in studies related to the structure of invertebrate communities in subterranean environments
and to identify the main environmental factors shaping these communities, we conducted a systematic literature
review encompassing terrestrial and aquatic cave habitats. Our analysis included 136 articles published between 1986 and
2025, identifying at least 57 environmental variables influencing the structure of subterranean assemblages. The period from
2014 to 2021 was marked by a notable increase in the quantity and quality of studies. Among the key factors, temperature
and distance from cave entrances emerged as primary determinants of species composition and richness in subterranean
aquatic fauna, with rising temperatures being a concern due to their potential negative impacts on these species. For terrestrial
fauna, distance from the entrance proved significant: the farther from the entrance, the lower the species richness and
diversity. Conversely, variables such as trophic potential, substrate heterogeneity, and cave size were identified as positive
factors, promoting higher species richness in terrestrial cave habitats. Despite these advancements, significant knowledge
gaps persist, particularly in biotic interactions, ecological succession, functional ecology, landscape ecology, and metacommunities.
Addressing these gaps is essential to deepen our understanding of subterranean ecosystems and reduce existing
knowledge disparities, promoting more effective conservation strategies for these unique environments.
... Therefore, it is essential to conserve these historic sites, not only to preserve their cultural value, but also to understand the influence of climate change. As demonstrated by Mammola et al. [1], caves can be utilised as natural laboratories to investigate the impacts of global climate change on subterranean ecosystems. The remarkable thermal stability of caves and the strong correlation between internal and external temperatures make them ideal for examining climate disturbances. ...
The conservation of cultural heritage is becoming an increasingly significant social issue because of climate change. Lascaux Cave, a UNESCO World Heritage Site, is particularly susceptible to disruption, which could result in the alteration of its delicate microclimate and accelerate the deterioration of the decorated walls. To mitigate the impact of these changes, it is essential to gain a deeper understanding of the thermal behaviour within the cave and its surrounding environment. The objective of this study was to examine the thermal behaviour of the cave, with a particular focus on the interactions between external temperature fluctuations, geological heterogeneity, and the internal microclimate of the cave. To investigate this phenomenon, a thermal monitoring system comprising 21 sensors (ALMEMO PT-100) was strategically placed in different zones of the cave, and a thermal station was installed outside the cave. The findings of this study demonstrate a substantial correlation between external and internal temperatures, exhibiting notable phase shifts and relative amplitude changes at varying depths and locations within the cave. The combination of thermal data with the geological heterogeneity of the rock mass demonstrated that the distinct thermal properties of different geological formations exert a considerable influence on thermal wave propagation. Furthermore, we examined how natural convection is caused by temperature differences between the vault and the ground of the cave and between the upper and lower galeries. The findings of this study can be used to develop future thermoaeraulic simulations. Understanding these thermal dynamics is necessary for developing effective conservation strategies.
... Biodiversity is globally in crisis and the subterranean species are likely to be particularly affected (Mammola et al., 2019;Boulton, 2020). Habitats such as caves, mines and railway tunnels share similarities with regards to their environmental conditions, such as food scarcity, high relative humidity, thermal stability, and lack of light (Keith et al., 2020). ...
Biodiversity is globally in crisis and the subterranean species are likely to be particularly affected (Mammola et al., 2019; Boulton, 2020). Habitats such as caves,mines and railway tunnels share similarities with regards to their environmental conditions, such as food scarcity, high relative humidity, thermal stability, and lack of light (Keith et al., 2020).
... Other risks are also associated with climate change. For example, some organisms from the external environment may seek refuge in underground ecosystems in the future due to climate change (Mammola et al., 2019b). Although caves serve as temporary shelters for surface and underground species that have adapted to these environments, they also act as dead-end traps for the original inhabitants of the caves (Biswas, 2010). ...
Cave fungi represent a diverse array of species that underwent speciation beyond their subterranean confines, providing several benefits to the biosystems they inhabit. Caves are hotspots for diverse fungal species. Despite the large number of known caves in Brazil, a megadiverse country, only a few studies have assessed the mycobiota in the karstic ecosystem. Herein, we present a state-of-the-art bibliometric review of the cave fungi in Brazil discussing the past and ongoing research in the country and highlighting the important historical milestones and aspects of Brazilian speleomycology. Based on the data from 30 publications, only the mycobiota in 30 caves in four Brazilian biomes (Amazon, Atlantic Forest, Cerrado, and Caatinga) have been assessed to date. Moreover, 292 fungal genera belonging to six phyla (Ascomycota, Basidiomycota, Basidiobolomycota, Chy-tridiomycota, Mucoromycota, and Mortierellomycota) have been recorded, and a few operational taxonomic units have been identified as Rozellomycota and Kickxellomycota. Sordariomycetes is the most representative class identified to date. Aspergillus and Penicillium are the most frequent genera detected in all surveyed caves. Cerrado biome accounts for the largest number of studies (18), both for inventoried caves and fungal communities, and 70% of fungal genera have been exclusively recorded in this biome. Nearly half of the cave fungi known worldwide are found in only 30 caves in Brazil (approximately 0.1% of the known caves in the country), emphasising the importance of Brazilian caves as reservoirs of overall biodiversity. Speleomycology focuses on this "invisible diversity," highlighting the necessity of cave conservation, even in megadiverse countries such as Brazil.
... Changes in underground temperatures are, however, more or less delayed compared to those experienced in surface environments, depending on air circulation, hydrology, presence of ice, and presence of bats, but available archives usually point to rather short lags, though it may require up to a few decades in special cases [65]. In any case, subterranean environments will be subjected to the effects of climate change [66,67]. ...
A new species of Collembola in the genus Coecobrya, C. microphthalma sp. nov., is described from a cave environment in Saraburi province, central Thailand. The new species is the second described species of the boneti-group found in the country. It is most similar to C. chompon Nilsai, Lima & Jantarit, 2022, which is also described from a Thai cave. However, the new species is morphologically different from C. chompon in having orange dot pigmentation on its body and a combination of other morphological characteristics such as the number of sublobal hairs on the maxillary outer lobe and the number of medio-sublateral mac on Th. II, Abd. I, Abd. III and Abd. IV and the anterior face of the ventral tube. The morphological comparison of all known boneti species and a key to the world species of Coecobrya of the boneti-group are given. Coecobrya microphthalma sp. nov. was successfully cultured in the laboratory. The thermal tolerance of the new species was studied and tested with seven different temperature experiments (27 °C as a control, 30, 32, 33, 34, 35 and 36 °C). The results showed that C. microphthalma sp. nov. cannot survive at a temperature higher than 32 °C after exposure to the experimental heat for 7 and 14 consecutive days. At 27, 30 and 32 °C, C. microphthalma sp. nov. remained alive and produced eggs, but the duration of egg production and number of egg-laying days significantly declined when the temperature increased (p < 0.001). An interesting aspect of their reproduction concerns temperature. At 32 °C (5 °C above the control temperature), the F1 generation survived, was active and was able to molt to the adult stage. However, specimens were unable to produce the next generation of offspring. For postembryonic development, C. microphthalma sp. nov. required six molts to reach the adult stage. The development rate (from egg to adult) varied and differed significantly between the tested temperatures (p < 0.001). An increase in temperature from the control temperature significantly accelerated the developmental rate from egg to juvenile instars to adult with a statistical significance (p < 0.01). This study is the first attempt that provide information on the impact of increasing temperature on the population dynamics, reproductive capacity and life history of a subterranean tropical Collembola.
... New species are continuously being found, both morphologically indistinguishable (so called cryptic) as well as morphologically distinct. However, accurate reconstruction and resolution of their phylogenetic relationships as well as reconstructions of their ecology and biogeography require a complete taxonomic structure (Mammola et al. 2019;Esmaeili-Rineh et al. 2020;Petković et al. 2020). Due to numerous morphologically cryptic species, the taxonomy of Niphargus should rely on both molecular and morphological analyses. ...
... Anthropogenic pressure on subterranean ecosystems and species is intensifying [90]. Climate change is the main factor altering the microclimate within caves, whereas habitat degradation, driven by pollution, mining, recreational tourism, and other forms of land use, threatens their structural integrity [90][91][92]. Troglobitic organisms frequently possess low thermal tolerance and limited vagility, rendering them particularly vulnerable [1,2,16]. Without prompt and effective conservation strategies, unique subterranean habitats and the specialized species they shelter face an inevitable decline [90]. ...
Cavernicolous scorpions are difficult to collect and study due to their often-inaccessible habitats. Some have evolved unique morphological adaptations, known as troglomorphies, including reduced sclerotization and pigmentation, reduction and/or loss of eyes, attenuation and elongation of the appendages, which assist them to thrive in dark, humid and low-energy input environments. Cavernicolous scorpions are classified into accidentals, trogloxenes, troglophiles, and troglobites. The Balkans, and particularly the Dinaric Karst region, host a diverse cave-adapted fauna, including scorpions. Despite an 1895 report of a blind scorpion from Bosnia and Herzegovina, the first truly troglobitic European scorpion, Euscorpius studentium Karaman, 2020, was only described a few years ago, based on two immature specimens. In the present contribution, this unique species is redescribed based on the first adult specimens; the ecological classification of all currently known cavernicolous Euscorpiidae Laurie, 1896, is updated; a key to the identification of cavernicolous scorpions occurring in the Dinaric Karst is provided; and the historical and geographical factors affecting the distribution and conservation of cavernicolous scorpions in the Balkans is reviewed.
... Finally, warming of subterranean environments will potentially have a large impact on biota. For example, Mammola et al. 20 argued that caves are largely unexplored habitats for species (bats, spiders, bacteria) that are likely to be sensitive to even small changes in the microclimate 56 . ...
Cave air temperatures in four caves in the European Alps show statistically significant warming trends of about 0.2 °C per decade over the last two decades (2000–2020). These trends are about half as large as those observed outside and are characterized by a remarkable spatial and temporal consistency. The investigated caves represent different types in terms of their ventilation regime and one of them also hosts perennial ice. Key observation sites are located in cave sections where the temporal variability of air temperature is strongly attenuated compared to outside conditions and data from different cave sections show that the main results are valid for large parts of the investigated caves. Continued warming will lead to broad changes in alpine cave environments, including changes in strength and direction of air flow in caves, karst hydrology and subsurface ecosystems. The observed subsurface warming has a particular strong effect on the long-term preservation of perennial ice present in some of these caves. This is shown for an ice cave in the Austrian Alps, where enhanced melt of ice correlates with the observed warming. This cave (and similar ones) will not be able to hold perennial ice beyond the next decade.
Supplementary Information
The online version contains supplementary material available at 10.1038/s41598-024-78658-y.
... their geographic range (Ammerman et al. 2012, Perry 2013. Global climate change is altering subterranean microclimates, potentially negatively impacting the survival of hibernating bats (Frick et al. 2019, Mammola et al. 2019. Roost disturbance from human recreation and mine closures, both purposeful and natural (e.g., cave-ins, landslides), is further reducing already limited winter roost availability (Ducummon 2000, Frick et al. 2019. ...
... The cave environment is unique, characterised byhaving stable temperature and humidity levels (Lobo 2012;Mammola et al. 2019), and for offering rich niche diversification for potential colonists, aquatic and terrestrial alike. Cave environments, however, are also deemed as being fragile, dependent on allochthonous energy resources to maintain a truncate food web (lacking primary producers) of highly endemic aquatic and terrestrial biota. ...
Three new cave-dwelling aeglid species from the Alto Ribeira karst region, south-eastern Brazil, are described. Morphological descriptions are based on traits traditionally used in aeglid taxonomy. Molecular phylogeny reconstruction based on the partial fragments of the 16S ribosomal RNA (16S rDNA) and the cytochrome oxidase subunit I (COI) revealed that: (1) dispersal of epigean aeglids toward the Alto Ribeira karst area occurred at two separate events in the evolutionary history of freshwater aeglids; (2) extant cave-dwelling aeglid species form two distinct subclades, each of which originated from a distinct ancestral epigean lineage; and (3) successful adaptation to subterranean habitats, as seen in extant cave-dwelling aeglid species from the Alto Ribeira karst area, developed independently within each subclade, as each one of them comprised an exclusive group of both stygobitic and stygophilic species.
ZooBank: urn:lsid:zoobank.org:pub:3F2D0A63-B86E-421F-9B29-DD605BF7B4E7
... Impacts of rapid climate change and anthropogenic activities that induce modifications in the physicochemical parameters of the environment (i.e. temperature, salinity and oxygen) are expected to affect groundwater communities [5][6][7][8][9], however, the impacts of these changes on groundwater species vary among species and the particular environmental change itself, which makes accurate projections for the future very difficult [4,6,[10][11][12][13]. Anchialine ecosystems (Box 1) in the Yucatan Peninsula (YP) are considered seasonally stable, with environmental changes occurring at broader timescales (such as glacial and interglacial epochs). ...
Anchialine systems are coastal groundwater habitats around the world which host a unique community of cave adapted species (stygobionts). Such communities are expected to be separated by haloclines into either fresh or saline groundwater communities, hence climate changes (e.g., eustatic sea level shifts) and anthropic driven changes (e.g., salinization) may have a great impact on these stygobiont communities. Here we used cave-restricted species of Typhlatya from the Yucatan Peninsula as models to identify physiological capacities that enable the different species to thrive in marine groundwater (T. dzilamensis) or fresh groundwater (T. mitchelli and T. pearsei), and test if their distribution is limited by their salinity tolerance capacity. We used behavior, metabolic rates, indicators of the antioxidant system and cellular damage, and lactate content to evaluate the response of individuals to acute changes in salinity, as a recreation of crossing a halocline in the anchialine systems of the Yucatan Peninsula. Our results show that despite being sister species, some are restricted to the freshwater portion of the groundwater, while others appear to be euryhaline.
... This information suggests that novel taxa of Actinobacteria, as yet unexplored species, inhabit Sof Umer Cave ecosystems. Actinobacteria, characterized by their ability to produce bioactive compounds [4] and tolerate extreme conditions, commonly inhabit cave ecosystems [42], contributing to nutrient cycling and organic matter decomposition [43]. ...
Sof Umer Cave is the largest cave in East Africa and located in southeastern Ethiopia, is an unexplored extreme environment harboring novel microbes and potential genetic resources. However, the microbial ecology and their potential genetic resource, remain undiscovered. The purpose of this study was to employ high-throughput shotgun sequencing to explore the microbial diversity and functional gene dynamics within the microbiomes of Sof Umer Cave. High-molecular-weight DNA was extracted from homogenized sample using the GeneAll DNA Soil Mini Kit and 1% CTAB-SDS method. Purified environmental DNA was sequenced using a NovaSeq PE150. Microbial gene analysis revealed that Sof Umer Cave is primarily inhabited by Protobacteria, Actinobacteria, Bacteroidota, Verrucomicrobiota, Acidobacteiota, and Cyanobacteria, according to the Micro-RN database. The functional genes identified through the KEGG, eggNOG, and CAZy databases included 44,780 genes involved in metabolism and the biosynthesis of bioactive compounds. However, 34,716 genes related to metabolic processes remained unidentified, suggesting the presence of potentially novel genes for the discovery of natural bioactive compounds. Additionally, functional gene modeling using the FBA-built metabolic model, Model seed and MS2-prokaryotic metabolic model revealed 1,742 reactions, 1,542 compounds, and the addition of 302 new reactions during gap filling. Finally, the results revealed that the Sof Umer Cave is a reservoir for novel microbes and diverse functional genes, offering potential for the discovery of natural bioactive compounds.
... Conserving caves is a challenge even in protected areas (Bejec et al., 2020). In fact, subterraneans ecosystems are among the most fragile, neglected and threatened in the world (Mammola et al., 2019;Sánchez-Fernández et al., 2021;Tanalgo et al., 2018;Trajano et al., 2016;Wynne et al., 2021). Therefore, regardless of the priority indicated by the BCVI, we believe that all the caves studied are important and unique, requiring urgent interventions to define priority areas for conservation, actions to strengthen and maintain protected areas and regulate anthropic activities in the region. ...
The Carajás region is home to the largest number of iron caves in Brazil, but studies that integrate elements of biological diversity and landscape characteristics are scarce. We present the first study based on the bat cave vulnerability index (BCVI), which uses bats as a key species for prioritizing caves in South America, whose objective was to assess the biotic potential and vulnerability of caves in the Carajás region, determining priority sites and the most effective conservation actions. The study took place from August 2021 to March 2023, where an inventory of the chiropterofauna of 12 caves was carried out. We recorded 16 bat species, two of which are vulnerable to extinction – Furipterus horrens (Cuvier, 1828) and Natalus macrourus (Gervais, 1856) – and two endemics to the Amazon region – Hsunycteris aff. thomasi (Allen, 1904) and Phyllostomus latifolius (Thomas, 1901); as well as one species with insufficient data to delimit its endemicity or threat status (Lonchophyllinae sp.). Mining is the main anthropogenic activity in the region, but tourism is also present and acts as a potential source of disturbance to the caves. The BCVI revealed three high priority caves for conservation and four with medium priority, indicating that these habitats are vulnerable to species loss and population decline due to exposure to anthropogenic activities and habitat destruction, thus requiring more effective conservation strategies. Considering the uniqueness of the subterranean habitats, we recommend re‐evaluating the proposals for expanding mining activities, implementing controlled tourist visitation plans and conducting ecological studies and long‐term monitoring.
... Understanding heat transfer in karst systems is a key issue for underground biota (Mammola et al., 2019), preservation of cave art (Bourges et al., 2014), speleothem growth rates (Banner et al., 2007;Spötl et al., 2005), or paleoclimate reconstruction (Borsato et al., 2016;Casteel & Banner, 2015;Domínguez-Villar et al., 2021). However, heat transfer in karst results from an intricate coupling between several mechanisms, including heat conduction in the rock mass (Quindos et al., 1987), convection due to water or air flow in caves (Cropley, 1965), or radiative transfer between cave walls (Guerrier et al., 2019). ...
The present study focuses on heat transfer in ventilated caves for which the airflow is driven by the temperature contrast between the cave and the external atmosphere. We use a numerical model that couples the convective heat transfer due to the airflow in a single karst conduit with the conductive heat transfer in the rock mass. Assuming dry air and a simplified geometry, we investigate the propagation of thermal perturbations inside the karst massif. We perform a parametric study to identify general trends regarding the effect of the air flowrate and conduit size on the amplitude and spatial extent of thermal perturbations. Numerical results support the partition of a cave into three regions: (a) a short (few meters) diffusive region, where heat mainly propagates from the external atmosphere by conduction in the rock mass; (b) a convective region where heat is mainly transported by the air flow; (c) a deep karst region characterized by quasi‐constant temperatures throughout the year. Numerical simulations show that the length of the convective region is approximately proportional to the amplitude of the flowrate annual fluctuations divided by the square root of the cave radius. This result is tested against field data from a mine tunnel and two caves. Our study provides first estimates to identify climate sensitive regions for speleothem science and/or ecosystemic studies.
... In caves that are highly susceptible to surface temperature fluctuations, climate extremes may be detected inside the cave that threaten subterranean biota and ecosystem services [6]. In the case of Postojna Cave, cave fauna is not thought to be threatened yet by climate extremes [7], although it is accepted that subterranean species are particularly sensitive to climate change, and there is the urgent need for future research, monitoring programs and conservation measures [8]. ...
The Biospeleological Station (BS) in Postojna Cave, with a volume of 36,000 m 3 , 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.
... It has been argued that subterranean organisms, as a consequence of less variable environmental conditions in the subterranean realm, are more susceptible to many types of environmental perturbation, including global warming [144], and the tone of many papers is that subterranean habitats and their fauna are delicate and vulnerable [145]. ...
Since the 1980s, with the widespread use of the phrase biodiversity [...]
... However, even if a high spatial heterogeneity was demonstrated in the composition of this fauna, this, by itself, does not mean that there would or would not be evidence of gene flow between populations of the same species, since the data tested belong exclusively to the superficial layer of the MSS. Furthermore, although some studies have discussed that IF caves with more troglobiotic species have lower species replacement values, considering them more ecologically "stable" (Di Russo et al. 1997;Mammola et al. 2019), contrary to our expectations, the values of total β-diversity in the MSS were high for both troglobiotic and non-troglobiotic animals. This fact reinforces the idea of moderate-to-low ecological connectivity between the sampling sites in the MSS, even if the environment presents favorable conditions for the evolution and permanence of the fauna. ...
Iron Formations (IF) are among the most threatened environments due to the extensive mining activities. Mesovoid Shallow Substratum (MSS) in IF represents a poorly known subterranean environment and evaluating its fauna has the potential for expanding knowledge about the distribution of troglobiotic populations. We evaluated the spatiotemporal distribution of the subterranean fauna in the MSS of IF in Brazil. We sampled the MSS invertebrate fauna and described the community patterns of troglobiotic and non-troglobiotic species. A total of 22,821 individuals and 276 morphospecies belonging to two phyla were found: Annelida and Arthropoda. Acariformes, Diptera, Hymenoptera, Blattodea, and Collembola represented 92.2% of the individuals sampled. Nine troglobiotic morphospecies belonging to four groups were sampled: Araneae (1), Entomobryomorpha (6), Poduromorpha (1), and Pseudoscorpiones (1). We found a high compositional dissimilarity of troglobiotic and non-troglobiotic species in terms of spatial β-diversity (among MSS sites) and temporal β-diversity (among months). The observed spatial β-diversity of troglobiotic species sampled in the MSS is greater than that of non-troglobiotic species. The temporal variation is similar for both groups. The richness difference component contributed more to spatial and temporal β-diversity for troglobiotic species, while higher replacement values for non-troglobiotic species were observed. Average values of temporal β-diversity and the replacement component were greater for non-troglobiotic than for troglobiotic species, while the richness difference component had an opposite pattern. The spatiotemporal β-diversity patterns suggest a medium-to-low connectivity of invertebrate populations that colonize the MSS, favoring the adoption of strategies for conserving broader areas in the context of IF.
... Climate-change influences on animal morphology besides overall body size effects have been recorded for several taxa (Anderson et al., 2019;Babin-Fenske et al., 2008;MacLean et al., 2019;Onley et al., 2020;Wereszczuk et al., 2023). In cave-dwelling bats such as M. schreibersii, the absence of a significant increase in body size over time might be attributed to the colonies' deeper location within karst underground sites, where the effects of climate change on temperature are less pronounced (Mammola et al., 2019). ...
Animal size, a trait sensitive to spatial and temporal variables, is a key element in ecological and evolutionary dynamics. In the context of climate change, there is evidence that some bat species are increasing their body size via phenotypic responses to higher temperatures at maternity roosts. To test the generality of this response, we conducted a >20-year study examining body size changes in 15 bat species in Italy, analysing data from 4393 individual bats captured since 1995. In addition to examining the temporal effect, we considered the potential influence of sexual dimorphism and, where relevant, included latitude and altitude as potential drivers of body size change. Contrary to initial predictions of a widespread increase in size, our findings challenge this assumption, revealing a nuanced interplay of factors contributing to the complexity of bat body size dynamics. Specifically, only three species (Myotis daubentonii, Nyctalus leisleri, and Pipistrellus pygmaeus) out of the 15 exhibited a discernible increase in body size over the studied period, prompting a reassessment of bats as reliable indicators of climate change based on alterations in body size. Our investigation into influencing factors highlighted the significance of temperature-related variables, with latitude and altitude emerging as crucial drivers. In some cases, this mirrored patterns consistent with Bergmann's rule, revealing larger bats recorded at progressively higher latitudes (Plecotus auritus, Myotis mystacinus, and Miniopterus schreibersii) or altitudes (Pipistrellus kuhlii). We also observed a clear sexual dimorphism effect in most species, with females consistently larger than males. The observed increase in size over time in three species suggests the occurrence of phenotypic plasticity, raising questions about potential long-term selective pressures on larger individuals. The unresolved question of whether temperature-related changes in body size reflect microevolutionary processes or phenotypic plastic responses adds further complexity to our understanding of body size patterns in bats over time and space.
... Understanding heat transfer in karst systems is a key issue for underground biota (Mammola et al., 2019), preservation of cave art (Bourges et al., 2014), speleothem growth rates (Banner et al., 2007;Spötl et al., 2005), or paleoclimate reconstruction (Borsato et al., 2016;Casteel & Banner, 2015;Domínguez-Villar et al., 2021). However, heat transfer in karst results from an intricate coupling between several mechanisms, including heat conduction in the rock mass (Quindos et al., 1987), convection due to water or air flow in caves (Cropley, 1965), or radiative transfer between cave walls (Guerrier et al., 2019). ...
The present study focuses on heat transfer in ventilated caves for which the airflow is driven by the temperature contrast between the cave and the external atmosphere. We use a numerical model that couples the convective heat transfer due to the airflow in a single karst conduit with the conductive heat transfer in the rock mass. Assuming dry air and a simplified geometry, we investigate the propagation of thermal perturbations inside the karst massif. We perform a parametric study to identify general trends regarding the effect of the air flowrate and conduit size on the amplitude and spatial extent of thermal perturbations. Numerical results support the partition of a cave into three regions: (1) a short (few meters) diffusive region, where heat mainly propagates from the external atmosphere by conduction in the rock mass; (2) a convective region where heat is mainly transported by the air flow; (3) a deep karst region characterized by quasi-constant temperatures throughout the year. An estimation of the length of the convective region is proposed and compared to field data from a mine tunnel and two caves. Our results provide first estimates to identify climate sensitive regions for speleothem science and/or ecosystemic studies.
... Este medio depende en gran medida del medio epigeo, del cual proviene la mayor parte de la energía (materia orgánica, detritus, deposición de guano, etc.); de esta forma, las alteraciones producidas en el exterior afectan también, en mayor o menor medida, al medio hipogeo (Mammola et al. 2019). A nivel mundial, algunas de las principales amenazas que perturban al medio subterráneo son la introducción de especies invasoras y sus patógenos asociados, el cambio climático, la sobreexplotación de sus recursos biológicos, la contaminación, la deforestación, la urbanización, las actividades agrícolas e industriales y, en algunos casos, el impacto del turismo (Mammola et al. 2022). ...
En Canarias el medio subterráneo terrestre habitable ocupa una elevada proporción del terreno e incluye hábitats diversos como los tubos de lava y otros tipos de cavidades volcánicas, la red profunda de grietas, el medio subterráneo superficial o los campos de piroclastos. Su extensión y frecuente interconexión permite la presencia de una gran diversidad de especies adaptadas a este medio (troglobiontes). Todas las arañas troglobiontes encontradas son endemismos canarios y cada isla, a excepción de Lanzarote, tiene sus propias especies. Tras los coleópteros, las arañas son el grupo de artrópodos con más troglobiontes en el archipiélago: 39 especies pertenecientes a 9 familias distintas. En este trabajo se aporta un listado de las arañas troglobiontes del archipiélago canario, se comentan datos relevantes de las distintas familias representadas, y se compara dicha fauna con la de otros archipiélagos oceánicos. Finalmente, se abordan las principales amenazas que afectan a estas especies y a la conservación del medio subterráneo en Canarias.
... Therefore, environmental filtering, primarily related to thermal ranges, appeared to mainly determine the set of species being unique to the different caves, and thus betweencave turnover. This may derive from the combination of two processes: (i) differences in temperature averages between regions may translate into differences in the timing and amount of groundwater recharge following ice and snow melting, along with rainfall, which in turn affects the degree to which non-stygobitic copepods can move in the groundwater through the hydrologic continuum between surface water and groundwater 85 ; (ii) since temperature within caves is generally correlated to surface mean annual temperature 86 , temperature patterns in the neighbourhoods of the different caves may directly translate into thermal differences in cave waters, thus shaping the corresponding assemblages based on the thermal niche breadth of the species forming the respective regional pools 87,88 . ...
Despite the study of subterranean biodiversity facing harsh sampling and mapping challenges, the huge diversity of taxa, ecological adaptations and evolutionary trajectories in subterranean environments is gaining increasing attention. Yet, the spatial and environmental factors driving the composition of groundwater communities are still poorly understood. To partially fill this knowledge gap, we collected copepod crustaceans from 12 caves along the Italian peninsula between 2019 and 2022, sampling each cave twice. The resulting presence-absence data were analysed to assess: (i) between-cave taxonomic beta diversity, also partitioning between turnover and nestedness-resultant dissimilarity; (ii) the relative weight of geographic distance and climatic differences in shaping observed beta diversity. Seventy-one species of copepods were collected overall. Pairwise beta diversity was high for most pairs of caves, with turnover being the major component. Geographic distance-decay models partially explained total beta diversity and turnover patterns. However, in Generalized Dissimilarity Models (GDM), including surface climatic conditions as predictors, the contribution of seasonal temperature averages was generally higher than that of geographic distance. Further, the explanatory and predictive performance of the GDMs notably increased, along with temperature contribution, when widening the spatial extent from which climate data were gathered. Our results confirmed a high spatial turnover in groundwater copepods’ assemblages and strengthened the link between regional climate and subterranean biodiversity.
... The microclimatic conditions inside caves resemble surface-level climatic conditions through conduction, air and water ow, and in ltration (Furey & Racey, 2015;Perry, 2013). Therefore, any changes in the surface level climatic conditions would alter the conditions inside the cave (Badino, 2004;Mammola, Piano, et al., 2019). Species inhabiting these systems are adapted to the stable microclimate inside a cave , and hence, are vulnerable to climatic uctuations. ...
The seasonal use of caves by bats can be attributed to physiologically demanding activities like mating and reproductions or torpor. Although cave use varies intra- and inter-specifically in bats, the microclimatic characteristics of roost sites have significant implications for the fitness of bat populations. As these microclimates are increasingly influenced by surface level climatic changes, understanding the current patterns of cave utilization is crucial to assess the impact of climate change on bats. Therefore, we monitored cave temperatures and studied the diversity and abundance of bats in 41 caves across a seasonal (mid-winter, late-winter and early-spring) and an elevational (400 to 2700 meters above sea level) gradient in the Central Himalayas. The richness and abundance of bat species exhibited seasonal variations, with more species and individuals present during early spring (n = 15) compared to mid-winter (n = 9). Species richness exhibited a linear decline with elevation in mid-winter, but remained relatively stable until 900 msl and then declined in late-winter and early-spring. Furthermore, species such as Hipposideros armiger (20.14 ± 1.60°C in spring and 17.97 ± 0.88°C in mid-winter), Rhinolophus affinis (19.98 ± 1.76°C in spring and 16.18 ± 3.09°C in mid-winter) and Rhinolophus cf. pusillus (19.55 ± 1.64°C in spring and 15.43 ± 2.87°C in mid-winter) preferred warmer microclimates during early-spring compared to mid-winter. This season- and species- specific cave use suggests that even minor fluctuations in cave temperatures could potentially alter the composition of bat communities inside caves. We recommend that long-term studies in such highly diverse climate vulnerable areas would help understand and predict the responses of cave-dwelling bats to climate change.
... Five populations are known so far (four if considering the two nearby localities in Roccaforte Mondovì as one), encompassing an estimated AOO of 16 km 2 and an EOO of 103 km 2 . We infer a decline in both EOO and AOO because of global warming due to the sensibility of troglobionts to increasing global temperature (see Mammola et al. 2019a). Dispersal ability for this species is not known but given the high development of troglomorphic characters and the restricted range, it is assumed to be very low. ...
The spider genus Typhlonesticus Kulczyński, 1914 (Araneae: Nesticidae) includes seven species, most of which exhibiting strict preference for caves, abandoned mines and other subterranean habitats. In Italy the genus is represented by two species: T. morisii (Brignoli, 1975), an extremely narrow endemic species from SW-Alps with a very high level of subterranean adaptation and T. idriacus (Roewer, 1931), showing a much wider distribution in NE-Italy and poor adaptations to subterranean life. Our recent biospele-ological surveys in the Alps lead to the discovery of new populations of highly troglomorphic Typhlonesticus that proved to belong to two new species based on morphological and molecular data. Considering the rarity of these new species, we provide general information on their ecology and distribution, including a comparative analysis of troglomorphic traits in Typhlonesticus in relation to biogeographic factors. Information on the conservation status, useful for assessing their extinction risk based on International Union for Conservation of Nature (IUCN) guidelines, is also provided.
... Subterranean ecosystems are extremely stable environments compared to their surrounding external ones (Poulson and White, 1969;Howarth, 1993). Species thriving in these habitats often show pronounced sensitivity to even small environmental changes, especially pertaining temperature and humidity (e.g., Barr and Kuehne, 1971;Howarth, 1980;Mammola et al., 2019;Nicolosi et al., 2021). Thus, there is concern about the possible effect of climate change on subterranean coenosis, also in the light of their reduced physiological tolerance (e.g., Novak et al., 2014) and poor dispersal ability (e.g., Cardoso, 2012;Mammola et al., 2015), which prevents them from shifting their distributional range towards newly appearing patches of suitable habitat (Mammola et al., 2018). ...
Meta menardi (Latreille, 1804) and M. bourneti Simon, 1922 (Araneae: Tetragnathidae) are ubiquitous inhabitants of the twilight zone of most hypogean sites across Europe. The two species are broadly distributed in Italy, including Sicily, where they show a remarkable segregation along the altitudinal gradient of Mount Etna. Thanks to our recent sampling activities in this area, we create a georeferenced dataset allowing the application of Species Distribution Modelling aiming at evaluating the current and the future habitat in light of the impacts caused by climate change on the local populations. We predicted a relatively wide suitable area for M bourneti, ranging from the sea level up to 1100 m a.sl., whereas for M. menardi the suitable area encompasses a narrow mid altitude strip, extending halfway between the areas suitable for M. bourneti, and the highly unsuitable volcanic uplands, heavily disturbed by the volcanic activity. The averaged future predictions for 2070 under RCP 8.5 scenario, show that M. bourneti will expand its range upwards, in areas that are now suitable for M. menardi. In turn, predictions for M. menardi indicate an extreme reduction of the current strip of suitable habitat, likely determining its local extinction. Our findings are further corroborated by the analysis of the bioclimatic niche of the two species assessed via multidimensional Hutchinsonian hypervolume, being much smaller in M. menardi compared to of M. bourneti. In light of our results, it seems likely that having wider climatic preference, M. bourneti will substitute M. menardi in most of its current range in Sicily. Future interventions aiming at the conservation of M. menardi on Mount Etna are strongly advised.
... Nesse sentido, é preciso compreender que, embora os processos geológicos sejam cíclicos, perdas na geodiversidade podem levar milhares ou milhões de anos para serem reestabelecidas, não sendo, portanto, consideradas renováveis na escala de tempo humana. Dessa forma, a perda de elementos, interrupções de processos naturais, poluição, entre muitos outros impactos no meio físico, incluindo o meio cárstico, devem ser entendidos muitas vezes como irreversíveis (Souza- Silva et al., 2015;Mammola et al., 2019;Chiarini et al., 2022). ...
Os benefícios diretos e indiretos que os serviços ecossistêmicos promovidos pela natureza prestam ao ser humano podem ser de inúmeras ordens: desde a água que é utilizada para diversos fins, até a biodiversidade, os recursos e os minérios que sustentaram a história evolutiva das civilizações. Diante das recentes ameaças que o patrimônio espeleológico brasileiro vem enfrentando, como tentativas de alteração dos decretos que regem sua proteção, este artigo busca contribuir para a discussão sobre os benefícios que as cavernas proporcionam nesse contexto, desde abrigo às primeiras civilizações até fonte de informações sobre o passado climático e pesquisas farmacoindustriais avançadas no futuro. Como método de análise, o presente estudo aplica os conceitos de serviços ecossistêmicos ao ambiente cárstico, assim como um método de levantamento de serviços “espeleossistêmicos” para a Caverna do Diabo (Gruta da Tapagem). Para contextualizar, o texto revisa como as discussões relacionadas aos serviços ecossistêmicos emergiram e evoluíram nas últimas décadas. O objetivo é, portanto, apresentar argumentos embasados na Economia Ecológica para sustentar estratégias de conservação em regiões cársticas, além de fornecer informações que contribuam para uma divulgação científica mais eficaz e para ações de educação ambiental. Acredita-se que categorizar os benefícios que as cavernas oferecem às populações humanas possa ser um recurso útil para argumentar contra o desconhecimento do patrimônio espeleológico diante das ameaças que enfrenta.
Conserving an underground heritage site in a karst environment poses significant challenges because of the complexity of the physical phenomena involved. The deterioration of cave walls is mainly caused by condensation and infiltration, which originates from the thermal behaviour of the cave and the surrounding rock mass. This phenomenon is difficult to describe because it depends on the heterogeneity and water content of the unsaturated rock mass. However, it is clear that the conservation of cave art is a matter of concern for all caves worldwide. The purpose of this study is to analyse the heterogeneities surrounding Lascaux Cave and identify those which are water-saturated (during the wet season) that could significantly influence the cave thermally. The rock mass was characterised using the non-destructive 2D electrical resistivity tomography (ERT) method. Before kriging the ERT data, Hierarchical Agglomerative Clustering (HAC) was performed on the dataset. This classification provides class boundaries for categorising the kriging-estimated resistivities. The results of this study significantly improve our understanding of rock mass from geological and hydrogeological perspectives. The creation of a 3D model helped to identify four areas of lower resistivity (water storage reservoirs), indicating the possible presence of water as the rock mass was partially saturated. Those water storage reservoirs coincide with the water flows recorded during wet periods inside the cave and are associated with known geological fractures. Moreover, identifying the different materials surrounding the cave and the saturated areas in the 3D model allows us to understand the deviations in the temperature measurements in different parts of the cave and will improve the accuracy of the heat transfer simulations.
Key words: Electrical Resistivity Tomography (ERT); Machine Learning; Kriging; Thermal analysis; Karst reservoirs; Conservation.
Most caves in temperate regions are energy-poor, leading to low richness and abundances of terrestrial macroinvertebrates. However, caves with abundant bat populations may represent a notable exception, as bat guano serves as a significant source of organic matter, supporting diverse specialized invertebrates. Yet, given the overall rarity of guano-rich caves in temperate region, their ecological dynamics are poorly understood. We conducted a year-long monthly standardized monitoring of the macroinvertebrates of the Buca dei Ladri cave, a guano-rich cavity in Tuscany, Italy. At each survey, we counted species within different sampling quadrats and collected environmental variables such as temperature, structural heterogeneity of the substrate, dominant substrate, and presence of bats. Over the year, we identified 31 macroinvertebrate species in the cave as both morphospecies and molecular lineages, based on mitochondrial COI and nuclear 18S genes. The latter approach hinted at the presence of cryptic diversity in some species. We observed an increase in species diversity with increasing structural complexity and the presence of bats, whereas a lower species diversity was found in guano-dominated substrates, probably due to the old age and subsequent low nutritional value of the historical guano deposits. Changes in the abundance of species within the cave were primarily explained by differences in structural complexity across sampling quadrats, whereas the distance from the cave entrance mostly explained species replacement. Our results underscore the importance of preserving healthy bat populations and a high habitat heterogeneity within the cave for the long-term conservation of the unique macroinvertebrate assemblages of the cave.
Karst depressions represent significant geomorphological features crucial in environmental monitoring and conservation. This research aims to detect and classify karst depressions according to their evolutionary stages in the Bambuí Group, located between the Cerrado and Caatinga biomes in Central Brazil, using Planet time series provided by Norway's International Climate and Forest Initiative (NICFI) Satellite Data Program and deep learning‐based semantic segmentation models. A new deep learning training dataset was developed containing manually labelled reference data and a time series of monthly images from Planet NICFI data over a year. The research classified three evolutionary stages of karst depressions: (1) temporary lakes, (2) depressions with concentric halos and subsidence and (3) vegetated depressions. These stages represent distinct geomorphological processes, from initial water accumulation to more advanced stages involving subsidence and vegetation development in the depression areas. The study compared six state‐of‐the‐art semantic segmentation architectures (U‐Net, U‐Net++, DeepLabV3+, LinkNet, FPN and PSPNet), each combined with three backbones (EfficientNet‐B7, ResNet‐101 and ResNeXt‐101), resulting in 18 model configurations. The best performing model (U‐Net with EfficientNet‐B7) achieved a mean Intersection over Union (mIoU) of 80 and IoU scores of 97.9 for the background, 80.93 for first stage, 79.89 for second stage and 63.35 for third stage, highlighting the challenges of detecting more advanced stages due to increasing vegetation cover and geomorphological complexity. The sliding window approach was employed to classify the entire image mosaic, testing various stride values (8, 16, 32, 64, 128 and 256), with smaller strides improving segmentation accuracy at the cost of higher computational demands. The results demonstrate the importance of integrating spectro‐spatio‐temporal data to detect multiple evolutionary stages and improve the robustness of semantic segmentation. This research provides a comprehensive dataset and benchmark for future studies on karst depressions, contributing to understanding geomorphological evolution and conservation planning in Central Brazil.
Microplastics (MPs) have been characterised in South African rivers, lakes, and the marine environment, yet we know less about MPs in subterranean environments. In this study, we assessed MP pollution in the sediment, subsurface water, and resident freshwater amphipod, Sternophysinx species across six South African subterranean cave systems. We hypothesised that MP pollution will increase with human visitations and activities in and around selected subterranean caves. We found MPs in sediments, subsurface waters, and amphipod species ranging from 4.9 ± 1.2 to 25.0 ± 6.9 particles/kg–1, 2.7 ± 0.7 to 15.0 ± 1.7 particles/L–1 and 2.1 ± 0 to 9.8 ± 3.1 particles/dry mass, respectively, with polypropylene being the most abundant polymer according to FTIR analysis. White fibres were dominant in sediments and water samples, whereas blue fibres were dominant in amphipods. Our results supported the hypothesis that MPs densities were correlated with human visitation and activities in and around the caves. The presence of MPs in subterranean caves presents a biodiversity and conservation threat to endemic and understudied cave-dwelling aquatic invertebrates, due to MPs ability to be transferable between trophic levels causing physiological constraints.
Extreme environments serve as natural laboratories for studying evolutionary processes, with caves offering replicated instances of independent colonisations. The timing, mode, and genetic underpinnings underlying cave-obligate organismal evolution remains enigmatic. We integrate phylogenomics, fossils, paleoclimatic modeling, and newly sequenced genomes to elucidate the evolutionary history and adaptive processes of cave colonisation in the study group, the North American Amblyopsidae fishes. Amblyopsid fishes present a unique system for investigating cave evolution, encompassing surface, facultative cave-dwelling, and cave-obligate (troglomorphic) species. Using 1,105 exon markers and total-evidence dating, we reconstructed a robust phylogeny that supports the nested position of eyed, facultative cave-dwelling species within blind cavefishes. We identified three independent cave colonisations, dated to the Early Miocene (18.5 Mya), Late Miocene (10.0 Mya), and Pliocene (3.0 Mya). Evolutionary model testing supported a climate-relict hypothesis, suggesting that global cooling trends since the Early-Middle Eocene may have influenced cave colonisation. Comparative genomic analyses of 487 candidate genes revealed both relaxed and intensified selection on troglomorphy-related loci. We found more loci under relaxed selection, supporting neutral mutation as a significant mechanism in cave-obligate evolution. Our findings provide empirical support for climate-driven cave colonisation and offer insights into the complex interplay of selective pressures in extreme environments.
Caves, once thought to be isolated ecosystems", are now understood to have intricate connections with surface environments, particularly evident at their entrances. These connections can significantly affect the microclimate within caves, leading to varying degrees of environmental stability. Our research explores the impact of microclimate conditions, specifically related to cave environmental stability, on biodiversity changes. We surveyed subterranean invertebrates during two different seasonal periods in 17 limestone caves in three karst regions in southeastern Brazil. Our analysis aimed to understand how environmental stability influences the overall richness of cave invertebrates and troglobitic species richness (restricted to subterranean habitats). We hypothesized that more stable caves would experience less fluctuation in relative species richness and lower turnover between seasons. Additionally, we anticipated that caves with greater environmental stability would harbor a higher richness of cave-restricted species in their length. Our findings support these hypotheses, revealing a significant positive correlation between cave environmental stability and species richness. Caves with higher environmental stability demonstrated lower species turnover rates between seasons, indicating enhanced community stability. While environmental stability significantly affected species richness, its influence on cave-restricted species was comparatively less pronounced. This suggests a complex interplay of factors shaping the unique fauna of caves. Nonetheless, the implications of climate change underscore the importance of preserving the environmental stability of these ecosystems. Using environmental stability as a guide can help protect cave biodiversity from the adverse effects of climate change, contributing to broader conservation efforts for these unique habitats.
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.
Species diversification is shaped by intricate interactions among biotic drivers, including gene flow, hybridization, and key innovations, and abiotic drivers, such as historical climate change, geological events, and ecological opportunity. However, the relative contributions of these drivers in large radiations remain poorly understood. We investigate the interplay among these factors in the diversification of Sinocyclocheilus, a cavefish radiation comprising 79 species. Sinocyclocheilus include typical surface-dwelling forms, with well-developed eyes and pigmentation, to cave-dwelling forms with regressed eyes, reduced pigmentation, and the presence of a horn and a hump. Using reduced representation genomic data (RADseq), we show extensive gene flow events across different species, with introgression playing a key role compared to incomplete lineage sorting in creating phylogenetic discordance and contributing genetic variation for cave adaptation and diversification in this group. Key traits such as eye degeneration, reduced pigmentation, and horn evolved independently multiple times, as adaptations for effectively exploiting cave environments. Furthermore, the uplift of the Tibetan plateau and the late Miocene cooling also significantly impacted speciation rates. Demographic analyses suggest population expansions during the Gonghe Movement and stability during the Last Glacial Maximum, possibly due to cave refugia. Periodic events of introgression promoted by isolation and reconnections due to the changing climate and geological activity, combined with the repeated evolution of key cave-adapted traits, are the primary drivers of this radiation. Our findings underscore the complex interplay of biotic and abiotic factors in the evolution of Sinocyclocheilus fish, offering new insights into the mechanisms of cave adaptation and diversification.
Stygobionts, namely animals with strong adaptations to subterranean environments that are unable to complete their life cycles outside groundwater, can be observed in spring ecotones, but their occurrence is generally considered accidental. The aim of this paper is to assess if stygobiont occurrence in springs is linked to specific environmental conditions or if it is random, irrespective of their features. For three years, we surveyed 59 spring sites recording the occurrence of vertebrate and invertebrate stygobiont species and assessing if spring features were related to their distribution. Moreover, we recorded the escape reactions of two easily identifiable stygobiont species. We detected six taxa usually considered as strictly stygobiont based on their troglomorphic features. Two of them were quite widespread: the salamander Proteus anguinus and the shrimp Troglocaris planinensis. Environmental characteristics were significantly related to the distribution of stygobionts. Hydroperiod and occurrence of flooding were the factors that played the strongest role in affecting occurrence. Our study suggests that the occurrence of stygobionts in springs is linked to specific habitat features rather than being a random mechanism and that the exploitation of ecotones can be important for the lifecycle of some species usually assumed to be strictly associated to caves.
ABSTRACT (EN)
The research focuses on the climatic conditions in lava caves, specifically Akeakamai Cave on Hawai'i. Lava caves, also known as pyroducts, are essential for studying cave ecology due to their unique microclimates which support highly specialized organisms.
Lava caves are formed from volcanic activity, creating hollow structures as lava flows cool. These caves are distinct from karst caves in terms of their formation, rock type, and climate regulation mechanisms. Lava caves tend to have high porosity and permeability, influencing air and water movement and thus the cave’s microclimate.
Climatic conditions in lava caves are influenced by various factors, including ground heat flux, water infiltration, and air movement. Unlike deep karst caves, lava caves are affected by surface temperatures, with heat transferred into the cave. Water from precipitation also plays a crucial role in regulating cave temperatures through its high heat capacity and conductivity. Air movement through cave openings and cracks facilitates heat exchange and evaporation, affecting temperature stability within the cave. The study emphasizes the significance of these environments in preserving rare minerals, archaeological findings, and microbial life.
Initial measurements confirmed the existence of different climatic zones within Akeakamai Cave, influenced by ventilation, moisture, and external temperatures. The study identified significant temperature and humidity fluctuations near cave entrances and more stable conditions deeper inside. Especially dead-end areas are climatically very stable. The research highlighted the importance of understanding the unique climatic processes in lava caves to protect their sensitive ecosystems. The findings suggest that climatic conditions in lava caves differ significantly from those in karst caves, necessitating tailored approaches for their study and conservation.
The research underscores the need for continuous and detailed climatic studies in lava caves to understand their unique environmental processes.
ABSTRACT (DE)
Die vorgestellte Forschung konzentriert sich auf die klimatischen Bedingungen in Lavahöhlen, insbesondere in der Akeakamai-Höhle auf Hawai'i. Lavahöhlen, auch bekannt als Pyrodukte, sind aufgrund ihres einzigartigen Mikroklimas und die dort lebenden, hochspezialisierte Organismen von wesentlicher Bedeutung für die Erforschung der Höhlenökologie.
Lavahöhlen entstehen durch vulkanische Aktivität und zählen zu den sogenannte Primärhöhlen, da sie sich mit dem Gestein bilden. Diese Höhlen unterscheiden sich von Karsthöhlen in Bezug auf ihre Entstehung, die Gesteinsart und die Mechanismen der Klimaregulierung. Lavahöhlen weisen in der Regel eine hohe Porosität und Durchlässigkeit auf, was die Luft- und Wasserbewegung und damit das Mikroklima der Höhle beeinflusst.
Die klimatischen Bedingungen in Lavahöhlen werden durch verschiedene Faktoren beeinflusst, darunter der Wärmefluss im Boden, die Wasserinfiltration und die Luftbewegung. Im Gegensatz zu tiefen Karsthöhlen werden Lavahöhlen von den Oberflächentemperaturen beeinflusst, wobei Wärme in die Höhle übertragen wird. Auch Niederschlagswasser spielt aufgrund seiner hohen Wärmekapazität und -leitfähigkeit eine entscheidende Rolle bei der Regulierung der Höhlentemperaturen. Luftbewegungen durch Tagöffnungen und zahlreiche Risse erleichtern den Wärmeaustausch und die Verdunstung, was wiederum die thermischen Bedingungen in der Höhle beeinflusst.
Die Studie unterstreicht die Bedeutung dieser Umgebungen für die Erhaltung seltener Mineralien, archäologischer Funde und mikrobiellen Lebens.
Die bisherigen Messungen bestätigten die Existenz verschiedener Klimatope in der Akeakamai-Höhle, die durch die Variationen in der Belüftung, den Feuchtigkeitsbedingungen und der Außentemperaturen beeinflusst werden. Die Studie ergab erhebliche Temperatur- und Feuchteschwankungen in der Nähe der Höhleneingänge und stabilere Bedingungen im Inneren der Höhle. Insbesondere Höhlengänge mit toten Enden zeigen sich klimatologisch extrem stabil. Die Forschungsergebnisse unterstreichen, wie wichtig es ist, die einzigartigen klimatischen Prozesse in Lavahöhlen zu verstehen, um ihre empfindlichen Ökosysteme zu schützen. Die Ergebnisse zeigen ebenfalls deutlich, dass sich die klimatischen Bedingungen in Lavahöhlen erheblich von denen in Karsthöhlen unterscheiden, was maßgeschneiderte Ansätze für ihre Erforschung und Erhaltung erforderlich macht.
Die Forschung unterstreicht die Notwendigkeit kontinuierlicher und detaillierter Klimastudien in Lavahöhlen, um deren einzigartige Umweltprozesse zu verstehen.
Climate change affects all ecosystems, but subterranean ecosystems are repeatedly neglected from political and public agendas. Cave habitats are home to unknown and endangered species, with low trait variability and intrinsic vulnerability to recover from human-induced disturbances. We studied the annual variability and cyclicity of temperatures in caves vis-à-vis surface in different climatic areas. We hypothesize that cave temperatures follow the average temperature pattern at the surface for each location with a slight delay in the signal, but we found three different thermal patterns occurring in caves: (1) high positive correlation and a similar thermal pattern to the surface, (2) low correlation and a slight thermal delay of the signal from the surface, and (3) high negative correlation with an extreme delay from the surface. We found daily thermal cycles in some caves, which may potentially control the circadian rhythms of cave organisms. Our results show that caves had lower thermal amplitude than the surface, and that thermal averages within caves approximately correspond to the to the annual average of surface temperature. Caves buffer external temperature and act as refugia for biota in extreme climatic events. Likewise, temperature increases at surface will lead to increment in caves, threatening subterranean biota and ecosystem services.
The cave microbiota is assumed to be shaped by indoor microclimate, biotic and abiotic factors, which are largely dependent from outside environmental conditions; however, this knowledge is available at local or regional scales only. To address this knowledge gap, we reanalyzed over 1050 bacterial and fungal communities of caves worldwide, and found that outdoor temperature and rainfall play a critical role in explaining differences in microbial diversity patterns of global caves, selecting specific dominant taxa across gradients of growing aridity conditions with arid climate leading to a reduction in total cave microbial diversity. Moreover, we found that fungal (from 186 to 1908 taxa) and bacterial (from 467 to 1619 taxa) diversity increased under temperate-tropical and temperate-continental climatic regions, respectively, highlighting an opposite preference for the two microbial compartments. We hypothesized that outdoor geographical, climatic variables and lithology are critical epistatic drivers in assembling microbial communities and their dominant taxa, whose ecological responses could be useful to predict the fate of these subterranean environments in the context of climate change. Our work elucidates the intimate connection between caves microbiota and surface ecosystems highlighting the sensitivity of cave microbial communities to climatic changes and environmental degradation. This work also provides a natural benchmark for the biogeographic information for caves globally and for protection strategies aiming at conservation of underground environments.
Phenotypic plasticity has been proposed as a mechanism facilitating the colonisation and adaptation to novel environments, such as caves. However, phenotypic plasticity in subterranean environments remains largely unexplored. Here, we test for plasticity in growth and development of fire salamander larvae (Salamandra salamandra) from subterranean and surface habitats, in response to contrasting food availability and light conditions. We hypothesized that: (i) low food availability and absence of light decrease larval growth and delay metamorphosis, (ii) light conditions mediate the effects of food availability on growth and time to metamorphosis, and (iii) larval response to contrasting light and food conditions is shaped by the habitat of origin. Our study showed that reduced food availability significantly delayed metamorphosis and slowed total length and body mass growth rates, while exposure to constant darkness slowed body mass growth rate. However, larvae slowed growth rates and increased time to metamorphosis without compromising size at metamorphosis. The effect of food availability on growth and time to metamorphosis did not change under different light conditions. Fire salamanders from subterranean and surface habitats responded differently only in relation to contrasting food availability conditions. Specifically, larvae from the surface habitat grew faster in high food conditions, while growth in larvae from the subterranean habitat was not influenced by food availability. Initial size also appeared to be an influential factor, since larger and heavier larvae grew slower, metamorphosed faster, and the size advantage was maintained in newly-metamorphosed juveniles. Overall, the results of our experiment suggest that plasticity and local adaptation favor the exploitation of aquatic subterranean habitats for breeding by fire salamanders, allowing successful development even under food shortage and day-length constraints, without compromising metamorphic size. Our findings have implications for conservation because they confirm that phenotypic plasticity plays a critical role in allowing fire salamanders to overcome altered environmental conditions. How to cite this article Băncilă RI, Stănescu F, Plăiaşu R, Nae I, Székely D, Vlad SE, Cogălniceanu D. 2023. Food and light availability induce plastic responses in fire salamander larvae from contrasting environments. PeerJ 11:e16046 http://doi.org/10.7717/peerj.16046
Abstract Cave‐dwelling ectotherms, which have evolved for millions of years under stable thermal conditions, could be expected to have adjusted their physiological limits to the narrow range of temperatures they experience and to be highly vulnerable to global warming. However, most of the few existing studies on thermal tolerance in subterranean invertebrates highlight that despite the fact that they show lower heat tolerance than most surface‐dwelling species, their upper thermal limits are generally not adjusted to ambient temperature. The question remains to what extent this pattern is common across subterranean invertebrates. We studied basal heat tolerance and its plasticity in four species of distant arthropod groups (Coleoptera, Diplopoda, and Collembola) with different evolutionary histories but under similar selection pressures, as they have been exposed to the same constant environmental conditions for a long time. Adults were exposed at different temperatures for 1 week to determine upper lethal temperatures. Then, individuals from previous sublethal treatments were transferred to a higher temperature to determine acclimation capacity. Upper lethal temperatures of three of the studied species were similar to those reported for other subterranean species (between 20 and 25°C) and widely exceeded the cave temperature (13–14°C). The diplopod species showed the highest long‐term heat tolerance detected so far for a troglobiont (i.e., obligate subterranean) species (median lethal temperature after 7 days exposure: 28°C) and a positive acclimation response. Our results agree with previous studies showing that heat tolerance in subterranean species is not determined by environmental conditions. Thus, subterranean species, even those living under similar climatic conditions, might be differently affected by global warming.
Islands are geographically defined as land masses completely surrounded by water, and island systems have been used as models for many biogeographic, ecological, and evolutionary theories ever since Darwin's pioneering efforts. However, their biological definition is complex. Over the past few decades these theories have been applied to many study systems that only share some geographic features with island systems. These features include spatial fragmentation, limited area, spatial and temporal isolation from adjacent parts of the system, and low connectivity between different parts within the system, to mention just a few. These systems vary in their form, the matrix that surrounds them, the factors defining their borders, the extent of insularity they impose on the different taxa, and their geological similarity to different types of actual islands. Here, I seek to understand whether such island‐like systems (ILS) function biologically as true islands. In the first part, I describe the wide diversity of ILS suggested in the literature and the variation in the features that define their insularity. In the second part, I review the extent to which the main theories of island biology are applicable to these systems: species–area and species–isolation relationships, community composition, evolutionary radiations, and the extent of endemism and genetic diversity. In the third and final part, I suggest a new conceptual framework within which to classify and study the biology of ILS, as well as practical future research directions. I conclude that the term ‘biological island’ is a multi‐faceted concept, loosely related to its geographical definition. As ILS are often less isolated than true islands, and their biological patterns are only partly similar to those of true islands (and even this is true only for some ILS) the use of the term ‘island’ to describe any isolated habitat is therefore inappropriate.
The use of semi‐isolated habitats such as oceanic islands, lakes and mountain summits as model systems has played a crucial role in the development of evolutionary and ecological theory. Soon after the discovery of life in caves, different pioneering authors similarly recognized the great potential of these peculiar habitats as biological model systems. In their 1969 paper in Science, ‘The cave environment’, Poulson and White discussed how caves can be used as natural laboratories in which to study the underlying principles governing the dynamics of more complex environments. Together with other seminal syntheses published at the time, this work contributed to establishing the conceptual foundation for expanding the scope and relevance of cave‐based studies. Fifty years after, the aim of this review is to show why and how caves and other subterranean habitats can be used as eco‐evolutionary laboratories. Recent advances and directions in different areas are provided, encompassing community ecology, trophic‐webs and ecological networks, conservation biology, macroecology, and climate change biology. Special emphasis is given to discuss how caves are only part of the extended network of fissures and cracks that permeate most substrates, and thus their ecological role as habitat islands is critically discussed. Numerous studies have quantified the relative contribution of abiotic, biotic and historical factors in driving species distributions and community turnovers in space and time, from local to regional scales. Conversely, knowledge of macroecological patterns of subterranean organisms at a global scale remains largely elusive, due to major geographical and taxonomical biases. Also, knowledge regarding subterranean trophic webs and the effect of anthropogenic climate change on deep subterranean ecosystems is still limited. In these research fields, the extensive use of novel molecular and statistical tools may hold promise for quickly producing relevant information not accessible hitherto.
Worldwide, there are at least 12 ILTER sites with an emphasis on karst, landforms arising from the combination of high rock solubility and well-developed solutional channel porosity underground, but the study of cave ecosystems has been largely neglected. Only two ILTER sites, both in Slovenia, are primarily caves. Caves are under-represented for several reasons, but especially because of the overall difficulty of access and the lack of a clear research agenda for cave ecosystem studies. We review several aspects of long-term studies in Postojna Planina Cave System (PPCS), proposing our approach as a model for ILTER research in caves. In PPCS, analysis of short-term temperature data shows a muted daily cycle and seasonality, and analysis of long-term temperature data shows an increase, largely the result of climate change. Changes in drip rate of epikarst aquifers above the cave are correlated with rainfall but with lags and complications resulting from differences in longer term rainfall patterns. Analysis of discharge rates indicates a rapid response to precipitation not only in the Pivka River at its sinking, but also at Unica Spring, where discharge is augmented from other parts of the aquifer, including epikarst. Quantitative analysis of the obligate epikarst-dwelling copepod community shows that, unlike most cave communities, complete sampling of the fauna is possible. Finally, organic carbon levels in PPCS indicate likely carbon limitation in the system. These five factors (temperature, drip rate, river discharge, epikarst copepod fauna, and organic carbon) are the appropriate variables for capturing the essential long-term trends in cave ecosystems and their causes.
1884 je pričel J. Marinitsch meriti in zapisovati temperature v Škocjanskih jamah in njihovi okolici. Meritve za čas 1886-1914 so bile zabeležene v “Höhlenbuch”. Leta 1928 so potekale podrobne mikroklimatske meritve sočasno v podzemlju in na površju. V letih 1960-1962 so člani ljubljanske univerze opravljali meteorološka opazovanja v jami in v udornici Velika dolina. 1992 so v okviru Inštituta pričeli z rednimi beleženji temperatur. Kasneje so v različne dele postavili 5 avtomatskih termometrov. Analizirani so rezultati dvoletnih opazovanj (maj 1997 - maj 1999) ter predstavljeni v tem prispevku. Čeprav so si letni povprečki precej podobni (10,6 ° in 10,1 °C), kažejo mesečni povprečki velika nihanja (od 1,6 ° do 17,3 °C), medtem ko so bile absolutne temperature v razponu od -1,5 ° do 21,9 °C. Najpomembnejša dejavnika za razporeditev temperature sta razdalja od vhoda in vertikalna lega. Primerjava temperature vode Reke in temperature zraka pri Mačji brvi kaže visoko stopnjo korelacije (R2 = 0,8994). Predhodna opazovanja v tem kratkem času kažejo, da je del Škocjanskih jam, kjer teče Reka, izrazito dinamična jama in da obiskovalci ne morejo preveč vplivati na tamkajšnja meteorološka dogajanja.
In 1884 J. Marinitsch started to measure and note down the data of temperature in the Škocjanske jame caves and nearby. The results for the period 1886-1914 are recorded in the “Höhlenbuch”. During the year 1928 detailed microclimatic measurements are performed simultaneously on the surface and underground. In the years 1960-1962 the members of the Ljubljana University have carried on the meteorological observations in the cave and specially in the collapse doline Velika dolina. In 1992 Karst Research Institute started to monitor the temperatures. Later on 5 temperature recorders were placed into different parts of the cave. The results of the two years (May 1997 - May 1999) were analysed and are presented in this paper. Although the annual mean values are rather similar (10.6° and 10.1°C), there is a great amplitude between the monthly mean values (1.6° to 17.3°). The absolute temperatures range between -1.5° and 21.9°C. The most important factors are distance from the entrance, and the vertical position. The comparison between temperatures of the Reka river and the air temperatures bears an important correlation. Previous results of this short period already show that the part of Škocjanske jame, where the Reka river is flowing, is an extremely dynamic cave and the visitors cannot have much impact on it’s meteorology.
One of the main challenges in ecology, biogeography and evolution is to understand and predict how species may respond to environmental changes. Here we focus on the deep subterranean environment, a system that minimizes most of the typical uncertainties of studies on epigean (surface) environments. Caves are relatively homogeneous habitats with nearly constant environmental conditions and simplified biological communities, allowing to control for biotic interactions. Thus, this particular system could be considered a natural habitat whose environmental conditions are similar to what can be reproduced in a laboratory, being an ideal model system for ecological, biogeographical and evolutionary studies. Subterranean species may potentially be used to assess the capability to persist in situ in a global change scenario, as they cannot accommodate to drastic changing conditions by behavioural plasticity, microhabitat use or by migrating to distant, more suitable areas, something frequent in epigean environments. In order to provide accurate predictions of the response of the subterranean biodiversity to climate change, we encourage evolutionary biologist, biogeographers and conservation biologist to work in this interesting ecosystem.
We studied the ecological continuum between caves and the associated network of fissures-Milieu Sou-terrain Superficiel (MSS)-in an hypogean site in the Graian Alps, Italy. Over one year, we surveyed the faunal assemblages by means of pitfall traps placed in the caves and specific subterranean sampling devices (SSD) buried in the MSS. We used generalized linear mixed models (GLMMs) and generalized additive mixed models (GAMMs) to compare the spatial and temporal dynamics of the subterranean invertebrates inhabiting the two environments. As expected, arthropod communities occurring near the surface were characterized by minor level of subterranean adaptations, and conversely, subterranean species were more abundant and diversified at higher depths, both in the caves and in the MSS. Diversity and abundance of external elements in the superficial layers were found to be highly seasonal dependent, with minor values in winter compared to the other seasons. We provided information about the faunal assemblages dwelling in the two hypogean compartments, and we characterized the microclimatic conditions therein. We discussed the existence of an ecological gradient of specialization extending from the surface to the deep hypogean layers, which can be interpreted in light of the microclimatic changes occurring at increasing depths and the parallel decrease in available organic matter.
The average global temperature is predicted to increase by 3 °C by the end of this century due to human-induced climate change. The overall metabolism of the aquatic biota will be directly affected by rising temperatures and associated changes. Since thermal stability is a characteristic of groundwater ecosystems, global warming is expected to have a profound effect on the groundwater fauna. The prediction that stygobitic (obligate groundwater dweller) species are vulnerable to climate change includes assumptions about metabolic effects that can only be tested by comparisons across a thermal gradient. To this end, we investigated the effects of two different thermal regimes on the metabolism of the stygobitic copepod species Diacyclops belgicus (Kiefer, 1936). We measured the individual-based oxygen consumption of this species as a proxy of possible metabolic reactions to temperature rising from 14 to 17 °C. We used a sealed glass microplate equipped with planar oxygen sensor spots with optical isolation glued onto the bottom of 80-μL wells integrated with a 24-channel fluorescence-based respirometry system. The tests have provided controversial results according to which the D. belgicus populations should be prudently considered at risk under a global warming scenario.
Over the last two decades there has been an exponential increase in the use of correlative species distribution models (SDMs) to address a variety of topics in ecology, biogeography, evolution, and conservation biology. Conversely, the use of these statistical methods to study the potential distribution of subterranean organisms has lagged behind, relative to their above-ground (epigean) counterparts. The reason for this is possibly related to a number of peculiarities of subterranean systems, which pose important limits, but also opportunities, for these correlative models. The aim of this forum is to explore the caveats that need to be made when generalizing these statistical techniques to caves and other subterranean habitats. We focus on the typical bias in spatial datasets of cave-dwelling species, and provide advice for selecting the model calibration area. In parallel, we discuss the potential use of different large scale surface variables to represent the subterranean condition. A more widespread adoption of these statistical techniques in subterranean biology is highly attractive and has great potential in broadening our knowledge on a variety of ecological topics, especially in the fields of climate change and biodiversity conservation. Their use would especially benefit the study of the biogeographic patterns of subterranean fauna and the impact of past and future climate change on subterranean ecosystems.
The threshold zones between the epigean and hypogean environments are generally characterized by less harsh ecological conditions than deep subterranean habitats, and usually support a greater abundance of organisms. Transitional habitats such as these should be more easily colonised by alien species, especially by those possessing exaptations suitable for subterranean life. In spite of this, few studies have been conducted to unravel the ecological dynamics between native and alien species in the habitats situated at the epigean/hypogean interface. A unique test case is offered by cave-dwelling Meta orb-weaver spiders in Great Britain (Araneae: Tetragnathidae). One species, M. menardi, is a widespread native, whilst M. bourneti is believed to be a recently introduced (1940s) species, that has since become established in the south-eastern part of the country. Species distribution models (SDM) were used to predict current and future habitat suitability for the two species, generating hypotheses regarding their distribution in different global warming scenarios. Model projections indicate that the two species respond to similar environmental variables. Seasonal temperature variations at the surface and elevation are the main factors explaining the distribution of both species, whereas annual precipitation, daily temperature range and limestone distribution contributed little to the model performance. It is predicted that due to climate change, there will be poleward shifts in the ranges of both species. However, the native species M. menardi will primarily be able to exploit suitable areas which will appear northward to their current distribution, and M. bourneti will colonise empty niches left available by its congeneric. The analytical framework employed in this paper may be easily adapted to other subterranean systems and species, stimulating future studies focusing on the distribution of native and alien species in extreme environments.
Caves are perceived as isolated, extreme habitats with a set of uniquely specialized biota, which long ago led to the idea that caves are ‘evolutionary dead-ends.’ This suggests that cave-adapted taxa may be doomed for extinction before they can diversify or transition to a more stable state. However, this hypothesis has not been explicitly tested in a phylogenetic framework with multiple independent cave-dwelling groups. Here we use the freshwater crayfish, a group with dozens of cave-dwelling species in multiple lineages, as a system to test this hypothesis. We consider historical patterns of lineage diversification and habitat transition as well as current patterns of geographic range size. We find that while cave-dwelling lineages have small relative range sizes and rarely transition back to the surface, they exhibit remarkably similar diversification patterns to those of other habitat types and appear to be able to maintain a diversity of lineages through time. This suggests that cave-adaptation is not a ‘dead-end’ for freshwater crayfish, which has positive implications for our understanding of biodiversity and conservation in cave habitats. This article is protected by copyright. All rights reserved
Seasonality impacts species distributions through changes of the environmental
conditions that affect the presence of individuals at a given place. Although the dynamics
of cave microclimates are well known, only a few studies have evaluated the effects
of such dynamics on non-strictly cave species. Here we assessed if species exploiting
subterranean environments show changes in habitat occupation related to seasonal
variation of cave microclimates. We surveyed 16 caves in central Italy every month for
one year. Caves were subdivided into longitudinal sectors of three meters. In each sector
we measured cave morphology and microclimatic features, assessed the occurrence
of eight non-troglobitic taxa (orthopterans, spiders, gastropods and amphibians),
and related species distribution to environmental features and sampling periods. The
occurrence of most species was related to both cave morphology and microclimatic
features. The survey month was the major factor determining the presence of species
in cave sectors, indicating that cave-dwelling taxa show strong seasonality in activity
and distribution. For multiple species, we detected interactions between sampling
period and microclimatic features, suggesting that species may associate with different
microhabitats throughout the year. The richest communities were found in sites
with specific microclimates (i.e., high humidity, warm temperature and low light)
but seasonality for species richness was strong as well, stressing the complexity of
interactions between outdoor and subterranean environments.
Subterranean organisms always attracted the attention of humans using caves with various purposes, due to the strange appearance of several among them and life in an environment considered extreme. According to a classification based on the evolutionary and ecological relationships of these organisms with subterranean habitats, first proposed by Schiner in 1854 and emended by Racovitza in 1907, three categories have been recognized: Troglobites, troglophles and trogloxenes. The Schiner-Racovitza system has been discussed, criticized, emended, the categories have been redefined, subdivided, original meanings have changed, but it is used until now. Herein we analyze in a conceptual framework the main ecological classifications of subterranean organisms, from Schiner to Trajano, in 2012, so far the last author to introduce a relevant conceptual change on the categories definitions, incorporating the source-sink population model. Conceptual inconsistencies are pointed, especially with regards to the generally ill-defined trogloxene category, and the correspondence between categories according to the original sense and in alternative classifications is discussed. Practical criteria for distinction between these categories and difficulties for their application are presented. The importance of rightly classifying subterranean populations according to the Schiner-Racovitza system for conservation of these fragile and mostly threatened habitats is discussed.
Subterranean ecosystems present ideal opportunities to study mechanisms underlying responses to changes in climate because species within them are often adapted to a largely constant temperature. We have characterized the thermal conditions of caves in the Western Alps, and related these hypogean climate data to the occurrence of Troglohyphantes spiders (Araneae, Linyphiidae). Our data indicated that present distributions reflect Pleistocene glaciation events and also pointed to specific responses as a consequence of changes in temperature. Constant temperatures recorded inside caves provide an approximation of the mean annual temperature outside, thus we extended the results to a regional scale. We used ecological niche modeling to predict habitat suitability both in the Pleistocene and under future global warming scenarios. These analyses pointed toward a future decline in habitat suitability for subterranean spiders and the potential extinction of the most restricted endemic species. When compared with other species that live in confined habitats such as islands and mountains, we expect cave species to be as much, if not more, vulnerable to climate change.
We investigated whether the equilibrium theory of island biogeography (ETIB) can be applied to the meiofauna of groundwater-fed springs. We tested whether cope-pod species richness was related with spring area, discharge, and elevation. Additionally, five hypotheses are tested based on species distribution patterns, dispersal ability, and life-history characteristics of several guilds (stygobiotic, nonstygo-biotic, cold stenotherm, and noncold stenotherm species). Thirty springs in the central Apennines (Italy) were considered. A multimodel selection procedure was applied to select best-fit models using both ordinary least-squares regressions and autoregressive models. Mantel tests were used to investigate the impact of spatial autocorrelation in determining interspring similarity (ßsor), pure turnover (ßsim), in-tersite nestedness (ßnest = ßsor − ßsim), and matrix nestedness (measured using NODF and other metrics). Explicit consideration of spatial correlations reduced the importance of predictors of overall species richness, noncold stenotherm species (both negatively affected by elevation), cold stenotherm species, and nonstygobiotic species, but increased the importance of area for the stygobiotic species. We detected nested patterns in all cases, except for the stygobites. Interspring distances were positively correlated with ßsor and ßnest (but not with ßsim) for the entire data set and for nonstygobiotic, cold stenotherm, and noncold stenotherm species. In the case of stygobites, interspring geographical distances were marginally correlated with ßsor and no correlation was found for ßsim and ßnest. We found support for ETIB predictions about species richness, which was positively influenced by area and negatively by elevation (which expresses the size of source of immigrants). Low turnover and high nestedness are consistent with an equilibrium scenario mainly regulated by immigration and extinction. Stygobites, which include many distributional and evolutionary relicts, have a low capability to disperse through the aquifers and tend to be mainly confined to the springs where they drifted out and were trapped by springbed sediments. K E Y W O R D S beta diversity, copepods, equilibrium theory, groundwater, island biogeography, nestedness
Geothermal energy plays an increasingly important role as a renewable energy source. However, it induces temperature changes in natural thermally static groundwater ecosystems. Temperature impacts can considerably alter the groundwater chemical composition and quality, the metabolism of organisms, and, consequently, biogeochemical processes and ecosystem functions. Combining original data from current studies with a compact review of recent findings, we show that a moderate increase in groundwater/aquifer temperature [+5 to 10 Kelvin (K)] generally causes only minor changes in water chemistry, microbial biodiversity, and ecosystem function in non-contaminated and energy-poor (oligotrophic) groundwater systems. In aquifers that are contaminated with organics, nutrients, and heavy metals—typical in urban areas and at sites with intensive land use (e.g., agriculture)—and particularly at temperatures ≥30 °C as regularly reached when heat is actively stored in aquifers, significant changes in water quality and ecological patterns can result. Here most critical are the heat-related mobilization of organic matter and contaminants (e.g., arsenic), the reduction and depletion of dissolved oxygen, and consequently the consecutive shift to anaerobic redox processes that may produce toxic and corrosive products (e.g., hydrogen sulfide) and greenhouse gases (e.g., methane and carbon dioxide). Severe temperature alterations lead to a reduced biodiversity of the aquifer’s microbial community with the establishment of atypical thermophilic assemblages. Groundwater fauna, which is specifically adapted to the cold groundwater habitat, may be sensitive to thermal changes at temperature increases of only 5 K with long-term emigration or direct lethal effects. From an ecological point of view, long-lasting or reoccurring temperature alterations need to be carefully evaluated and regulated in the future. We suggest developing local and regional vulnerability concepts for the sustainable and ecologically sound use of subterranean heat and cold.
The term Milieu Souterrain Superficiel (MSS) has been used since the early 1980s in subterranean biology to categorize an array of different hypogean habitats. In general terms, a MSS habitat represents the underground network of empty air-filled voids and cracks developing within multiple layers of rock fragments. Its origins can be diverse and is generally covered by topsoil. The MSS habitat is often connected both with the deep hypogean domain---caves and deep rock cracks---and the superficial soil horizon. A MSS is usually characterized by peculiar microclimatic conditions, and it can harbor specialized hypogean, endogean, and surface-dwelling species. In light of the many interpretations given by different authors, we reviewed 235 papers regarding the MSS in order to provide a state-of-the-art description of these habitats and facilitate their study. We have briefly described the different types of MSS mentioned in the scientific literature (alluvial, bedrock, colluvial, volcanic, and other types) and synthesized the advances in the study of the physical and ecological factors affecting this habitat---i.e., microclimate, energy flows, animal communities, and trophic interactions. We finally described and reviewed the available sampling methods used to investigate MSS fauna.
Climate predictions indicate that precipitation patterns will change and average air temperatures will increase across much of the planet. These changes will alter surface water and groundwater temperatures which can significantly affect the local and regional environment. Here, we examine the role of precipitation timing in changes to groundwater temperature in carbonate-karst aquifers using measured groundwater level and temperature data from the Konza Prairie Long-Term Ecological Research Site, Kansas. We demonstrate that shifts to increased cool-season precipitation may mitigate the increases in groundwater temperature produced by increases in average annual air temperature. In karst, the solution-enlarged conduits allow faster and focused recharge, and the recharge-event temperature can strongly influence the groundwater temperature in the aquifer. Our field data and analysis show that predictions of future groundwater conditions in karst aquifers need to consider changes in precipitation patterns, in addition to changes to average annual air temperature.
Caves are not colonised by all taxa present in the surface species pool, due to absence of light and the tendency to food limitation when compared to surface communities. Under strong species sorting during colonisation and later by the restrictive environmental filter, traits that are not adaptive in subterranean habitats may be filtered out. We tested whether cave communities were assembled by the restrictive regime propitiated by permanent darkness or by competitive exclusion due to resource scarcity. When compared to surface communities, the restrictive subterranean regime would lead to lower functional diversity and phenotypic clustering inside the caves, and the opposite should be expected in the case of competitive exclusion. Using isopods (Oniscidea) as model taxa, we measured several niche descriptors of taxa from surface and cave habitats, used a multivariate measure of functional diversity, and compared their widths. We found phenotypic overdispersion and higher functional diversity in cave taxa when compared to surface taxa. On the one hand, the dry climate outside of caves hampered the survival of several taxa and their ecological strategies, not viable under severe desiccation risk, culminating in the clustering of functional traits. In contrast, this restriction does not occur inside of caves, where isopods find favourable conditions under lower predation pressures and more amenable environmental parameters that allow occupation and subsequent diversification. Our results showed that, at least for some taxa, caves may not be such a harsh environment as previously thought. The high functional diversity we found inside caves adds an additional reason for the conservation of these sensitive environments.
For management strategies in the context of global warming, accurate predictions of species response are mandatory. However, to date most predictions are based on niche (bioclimatic) models that usually overlook biotic interactions, behavioral adjustments or adaptive evolution, and assume that species can disperse freely without constraints. The deep subterranean environment minimises these uncertainties, as it is simple, homogeneous and with constant environmental conditions. It is thus an ideal model system to study the effect of global change in species with poor dispersal capabilities. We assess the potential fate of a lineage of troglobitic beetles under global change predictions using different approaches to estimate their thermal niche: bioclimatic models, rates of thermal niche change estimated from a molecular phylogeny, and data from physiological studies. Using bioclimatic models, at most 60% of the species were predicted to have suitable conditions in 2080. Considering the rates of thermal niche change did not improve this prediction. However, physiological data suggest that subterranean species have a broad thermal tolerance, allowing them to stand temperatures never experienced through their evolutionary history. These results stress the need of experimental approaches to assess the capability of poor dispersal species to cope with temperatures outside those they currently experience.
High altitude karstic environments often preserve permanent ice deposits within caves, representing the lesser-known portion of the cryosphere. Despite being not so widespread and easily reachable as mountain glaciers and ice caps, ice caves preserve much information about past environmental changes and climatic evolution.
We selected 1111 ice caves from the existing caves inventory, predominantly but not exclusively located in the periglacial domain where permafrost is not dominant (i.e., with mean annual air temperature < 3°C but not in a permafrost environment). The influence of climate and topography on ice caves distribution is also investigated. In order to assess the thickness and the inner structure of the deposits, we selected two exemplary ice caves in the Canin massif (Julian Alps) performing several multifrequency GPR surveys. A strong influence of global and local climate change in the evolution of the ice deposits has been particularly highlighted in the dynamic ice caves type, especially in regards to the role of weather extremes. The natural response of ice caves to a warming climate could lead to a fast reduction of such ice masses. The increased occurrence of weather extremes, especially warmer and more intense precipitation caused by higher mean 0°C-isotherms, could in fact be crucial in the future mass balance evolution of such permanent ice deposits.
The unique morphology of cave animals has interested biologists at least since the time of Lamarck. After a number of non-adaptive explanations for the morphology of cave animals, especially with respect to eye and pigment loss, a neo-Darwinian explanation, emphasizing constructive morphological changes rather than losses, was put forward by Barr, Christiansen, and Poulson in the 1960’s. Emphasizing convergent evolution (troglomorphy), this paradigm has recently been challenged, with evidence of divergent selection and the widespread occurrence of morphologically similar species in other subterranean habitats, including ones with abundant food and relatively strong environmental fluctuations. An emerging paradigm emphasizes the central role of darkness in convergent evolution, and the role of habitat size and interspecific competition in divergent evolution of subterranean species.
Sprememba paradigme o evoluciji jamskega življenja
Edinstvena morfologija jamskih živali, predvsem v povezavi z izgubo oči in pigmenta, je zanimala biologe že od časa Lamarcka. Kasneje so bile predstavljene tudi druge, t.im. neodarvinistične razlage, s poudarkom na konstruktivnih morfoloških spremembah namesto izgubah, povzete s strani Barra, Christiansena in Poulsona v 60. letih 20. stoletja. Z novejšimi raziskavami o divergentni selekciji in razširjeni prisotnosti morfološko podobnih vrst v drugih podzemeljskih habitatih, vključno s tistimi, kjer je veliko hrane in z relativno velikimi okoljskimi nihanji, se je zamajala paradigma, temelječa na konvergentni evoluciji (troglomorfija). Novo nastajajoča paradigma poudarja osrednjo vlogo teme v konvergentni evoluciji, ter vlogo velikosti habitata in medvrstne kompeticije v divergentni evoluciji podzemeljskih vrst.
We review the current understanding of the physics of caves and karst. Our review focuses on research that has used simple physically based models to improve understanding of processes that occur in karst. The topics we cover include cave atmosphere dynamics, transport within karst conduits, and models of speleogenesis and related processes. We highlight recent advances in these subjects and attempt to identify promising areas for future work. In our judgment, many of the most intriguing open questions relate to the interactions between these three groups of processes.
Vzemimo valjasto jamo: pogled fizika na znanost o jamah in krasu
V članku pregledava trenutno poznavanje fizike jam in krasa. Pri tem se osredotočava na raziskave, ki so razumevanje kraških procesov poglobile z uporabo preprostih modelov na osnovi fizike. Obravnavava vedenje jamskega ozračja, transport v kraških kanalih in modele nastanka jam ter povezanih procesov. Izpostavljava sodobna dognanja na teh področjih in iščeva obetavne teme za nadaljnje raziskave. Po najinem mnenju so mnoga med bolj privlačnimi odprtimi vprašanji povezana z medsebojnim vplivom med obravnavanimi tremi skupinami procesov.
Anthropogenic climate change is predicted to be a major cause of species extinctions in the next 100 years. But what will actually cause these extinctions? For example, will it be limited physiological tolerance to high temperatures, changing biotic interactions or other factors? Here, we systematically review the proximate causes of climate-change related extinctions and their empirical support. We find 136 case studies of climatic impacts that are potentially relevant to this topic. However, only seven identified proximate causes of demonstrated local extinctions due to anthropogenic climate change. Among these seven studies, the proximate causes vary widely. Surprisingly, none show a straightforward relationship between local extinction and limited tolerances to high temperature. Instead, many studies implicate species interactions as an important proximate cause, especially decreases in food availability. We find very similar patterns in studies showing decreases in abundance associated with climate change, and in those studies showing impacts of climatic oscillations. Collectively, these results highlight our disturbingly limited knowledge of this crucial issue but also support the idea that changing species interactions are an important cause of documented population declines and extinctions related to climate change. Finally, we briefly outline general research strategies for identifying these proximate causes in future studies.
Opisan je razvoj jamskega monitoringa od 19. stoletja dalje. Prednost razvojnih teorij je omogočila doseči primerljive rezultate in napovedati razvoj jamske klime, še preden je prišlo do nepopravljivih procesov. Našteti so najpomembnejše parametri monitoringa. V zadnjih letih smo doživeli močan tehnološki razvoj in ocenjena je bila relativna pomembnost vsakega parametra. Novembra 1999 so odprli za obisk Kartchner Caverns, AZ, ZDA. Opravljenih je bilo nekaj predhodnih raziskav. Arizona Conservation Project, Inc. (ACPI) je predvidel 22 merilnih postaj. Dobili so oceno vpliva. Drugi primer je iz Cango Caves. Septembra 2000 so postavili preprosto mrežo za monitoring, ki naj bi delovala eno leto. Sestavljena je iz 15 preprostih “data loggerjev”, razporejenih po jami. Merijo temperaturo zraka in vode, koncentracijo CO2 in relativno vlažnost in vrednosti občasno prenesejo v računalnik izven jame. Prispevek podaja prve rezultate. Popolnoma avtomatičen monitoring bo postavljen v prihodnosti, ko bodo pregledani rezultati te prve preproste opazovalne mreže. Vzpostavili bodo popolnoma avtomatizirano mrežo, ko bodo razpolagali z rezultati prve preproste opazovalne mreže.
The evolution of cave monitoring since 19th century is described. The advantage of the development of theories was the possibility to obtain comparable results and forecast the evolution of a cave climate before irreversible modifications take place. The most important parameters to be monitored are indicated. In recent years both important technological improvements have been obtained and the relative importance of each parameter has been reviewed. Kartchner Caverns, Arizona, USA, was opened to the public in November 1999. Some preliminary studies have been performed. Arizona Conservation Project, Inc. (ACPI) established 22 monitoring stations. An evaluation of the impact assessment was obtained. The second case concerns Cango Cave. A simple monitoring network has been installed in September 2000 to be operated for one year. It consists in about 15 rugged data loggers distributed along the cave. Air and water temperature, carbon dioxide concentration, and relative humidity are measured and the values are transferred periodically by a shuttle into a computer outside the cave. A totally automatic monitoring network will be installed in the future after the results of the first simple network are achieved.
The stability of temperature and humidity in caves is well known. However, little is known if higher or lower cave environmental stability (temperature, humidity, light and others) implies changes in the structure of the biological communities. Number, position and size of entrances, then size, depth, host rock and extent of the cave, the amount and type of food resources are all factors that can have strong influence on the cave biological communities. The objective of the present study was to evaluate the correlation between the presence of water bodies, size of entrances and the linear development of caves with the terrestrial invertebrate richness and species composition in 55 limestone caves located in the Brazilian Savannah, sampled from 2000 to 2011. Invertebrates were sampled by active search throughout the caves, prioritizing micro-habitats (sites under rocks) and organic resources (litter, twigs, feces and bat guano). We recorded 1,451 invertebrate species. Species richness was positively correlated with presence of cave streams, width of entrances and linear development of the caves. The richness of troglomorphic species was positively correlated to the presence of perennial pools and linear development of the caves. The presence of cave streams was a decisive factor for determining the community structure, increasing the number and the similarity of troglophile species among the caves. Flood pulses can cause disturbances that eventually select the same species besides importing resources. However, for the terrestrial troglomorphic species the disturbance caused by cave streams may decrease the number of species.
Modern tourism at Postojnska jama (the Cave of Postojna) is approaching its 200th anniversary. Besides being an iconic trademark of destination tourism, the cave has a rich history of karstological and speleological investigations, and is also known as the cradle of speleobiology. Since 2009 systematic studies of cave microclimate and biology have been taking place to help provide guidelines for sustainable use of the cave and to mitigate the side effects of long-term tourism. Natural and anthropogenic impacts on cave micro-climate are being evaluated. The entrance to the cave used by tourists was artificially opened in 1866, and this has caused the cave to be well ventilated deep inside. This has both positive and negative influences on the cave environment, allowing the outside climate to impose a strong influence on the cave micro-climate. Statistical comparisons between historical cave air temperature (1852; 1933-1937) and the results of modern monitoring (2009-2013) show that the former average daytime cave air temperature for the inner part of the cave of between 7.5-8.4°C was about 2°C lower than present temperatures. The increase is mostly attributed to changes in natural climatic conditions, because the mean annual exterior air temperature has been increasing for several decades. To a lesser degree the cave air temperature increase can also be attributed to the higher number of tourist visits, when cumulative effects were observed. Successful management of the show cave must combine communication and interaction between researchers, cave owners, cave managers, the public and the State government.
The scorpion family Typhlochactidae Mitchell, 1971 is endemic to eastern Mexico and exclusively troglomorphic. Six of the nine species in the family are hypogean (troglobitic), morphologically specialized for life in the cave environment, whereas three are endogean (humicolous) and comparably less specialized. The family therefore provides a model for testing the hypotheses that ecological specialists (stenotopes) evolve from generalist ancestors (eurytopes) and that specialization (in this case to the cavernicolous habitat) is an irreversible, evolutionary dead-end that ultimately leads to extinction. Due to their cryptic ecology, inaccessible habitat, and apparently low population density, Typhlochactidae are very poorly known. The monophyly of these
troglomorphic scorpions has never been rigorously tested, nor has their phylogeny been investigated in a quantitative analysis. We test and confirm their monophyly with a cladistic analysis of 195 morphological characters (142 phylogenetically informative), the first for a group of scorpions in which primary homology of pedipalp trichobothria was determined strictly according to topographical identity (the ‘‘placeholder approach’’). The phylogeny of Typhlochactidae challenges the conventional wisdom that ecological specialization (stenotopy) is unidirectional and irreversible, falsifying Cope�s Law of the unspecialized and Dollo�s Law of
evolutionary irreversibility. Troglobitism is not an evolutionary dead-end: endogean scorpions evolved from hypogean ancestors on more than one occasion.
Caves and other subterranean habitats with their often strange (even bizarre) inhabitants have long been objects of fascination, curiosity, and debate. The question of how such organisms have evolved, and the relative roles of natural selection and genetic drift, has engaged subterranean biologists for decades. Indeed, these studies continue to inform the general theory of adaptation and evolution. Subterranean ecosystems generally exhibit little or no primary productivity and, as extreme ecosystems, provide general insights into ecosystem function. The Biology of Caves and other Subterranean Habitats offers a concise but comprehensive introduction to cave ecology and evolution. Whilst there is an emphasis on biological processes occurring in these unique environments, conservation and management aspects are also considered. The monograph includes a global range of examples from more than 25 countries, and case studies from both caves and non-cave subterranean habitats; it also provides a clear explanation of specialized terms used by speleologists. This accessible text will appeal to researchers new to the field and to the many professional ecologists and conservation practitioners requiring a concise but authoritative overview. Its engaging style will also make it suitable for undergraduate and graduate students taking courses in cave and subterranean biology. Its more than 650 references, 150 of which are new since the first edition, provide many entry points to the research literature.
The Anthropocene as a potential new unit of the International Chronostratigraphic Chart (which serves as the basis of the Geological Time Scale) is assessed in terms of the stratigraphic markers and approximate boundary levels available to define the base of the unit. The task of assessing and selecting potential Global Boundary Stratotype Section and Point (GSSP) candidate sections, a required part of the process in seeking formalisation of the term, is now being actively pursued. Here, we review the suitability of different stratified palaeoenvironmental settings and facies as potential hosts for a candidate GSSP and auxiliary sections, and the relevant stratigraphical markers for correlation. Published examples are evaluated for their strengths and weaknesses in this respect. A marked upturn in abundance of radioisotopes of 239Pu or 14C, approximately in 1952 and 1954 CE respectively, broadly coincident with a downturn in δ13C values, is applicable across most environments. Principal palaeoenvironments examined include: settings associated with accumulations of anthropogenic material, marine anoxic basins, coral reefs, estuaries and deltas, lakes at various latitudes, peat bogs, snow/ice layers, speleothems and trees. Together, many of these geographically diverse palaeoenvironments offer annual/subannual laminae that can be counted and independently dated radiometrically (e.g. by 210Pb). Examples of possible sections offer the possibility of correlation with annual/seasonal resolution. From among such examples, a small number of potentially representative sites require the acquisition of more systematic and comprehensive datasets, with correlation established between sections, to allow selection of a candidate GSSP and auxiliary stratotypes. The assessments in this paper will help find the optimal locations for these sections. (online first 30 Dec 2017; printed vers. March 2018)
Groundwater is an extreme environment due to its absence of light, resource scarcity and highly fragmentary nature. Successful groundwater colonizers underwent major evolutionary changes and exhibit eye and pigment loss (troglomorphies). Consequently, their chances of dispersal and survival in the well-connected surface waters are greatly decreased, resulting in significant endemism. The West Palaearctic subterranean amphipod genus Niphargus comprises hundreds of narrowly endemic and troglomorphic species. Nevertheless, a few are known to occur in surface waters, two of which, N. hrabei and N. valachicus, have extremely large ranges that even exceed those of many surface-water amphipods. We tested if this pattern results from a secondary colonization of the relatively well-connected epigean environment, and whether this ecological shift promoted the large-scale dispersal of these species. Results showed that despite their ecological and zoogeographic similarities, N. hrabei and N. valachicus are not closely related and independently colonized surface waters. Their phylogeographic patterns indicate Middle to Late Pleistocene dispersal episodes throughout the Danube lowlands, and relatively modest yet significant genetic differentiation among populations. Clustering based on morphology revealed that the two species are phenotypically closer to each other than they are to most other epigean congeners. We presume that the ecological shift to surface environments was facilitated by their ability to thrive in hypoxic waters where rheophilic competitors from the family Gammaridae cannot survive. In conclusion, our results indicate that adaptation to groundwater is not a one-way evolutionary path and that troglomorphic species can occasionally recolonize and widely disperse in surface waters.
AimTo describe the distribution of two congeneric species of cave-dwelling spiders under current climatic conditions and future warming scenarios, keeping into account their bioclimatic requirements, dispersal capacity and competition dynamics. LocationEurope and North Africa. Methods
We gathered detailed occurrence data for Meta menardi and M. bourneti (Araneae: Tetragnathidae) and modelled their distribution across their bioclimatic range. We evaluated the breadth of the bioclimatic niche of the two species and assessed the potential overlap between their multidimensional Hutchinsonian hypervolumes. We compared these results with their current distribution maps obtained by species distribution modelling (SDMs) keeping into account dispersal and competition dynamics, and we projected future trends of distribution according to different climatic scenarios. ResultsThe overall size of the niche hypervolumes of the two species was very similar and highly overlapping. However, when accounting for competition in the model, the predicted ranges of the two species showed only minor areas of overlap. On the base of SDM analysis, we predicted a significant poleward shift in the distribution of both species, with the appearance of a new contact area especially in Central Europe, southern UK, France and northern Spain. Main conclusionsInterspecific competition keeps the current ranges of the two European Meta species apart, although their fundamental bioclimatic niches are very similar. Rapid poleward shifts of the two species are likely due to the high dispersal capacity of the two spiders. The case of Meta spiders exemplifies rapid shift in range of distribution associated with global warming, which are unlikely to occur in the case of most cave-dwelling arthropods.
Dynamics of island biodiversity
Fifty years ago, MacArthur and Wilson published their influential book, The Theory of Island Biogeography . This work provided a quantitative framework for understanding the ecological processes governing the diversity of species on oceanic islands. Whittaker et al. review the subsequent progress in the field, focusing particularly on the integration of the ecological model with island geophysical dynamics. Recent work is showing how immigration, speciation, and extinction respond to the phases of emergence, development, and submergence in oceanic islands.
Science , this issue p. eaam8326
Bioregions are an important concept in biogeography, and are key to our understanding of biodiversity patterns across the world. The use of networks in biogeography to produce bioregions is a relatively novel approach that has been proposed to improve upon current methods. However, it remains unclear if they may be used in place of current methods and/or offer additional biogeographic insights. We compared two network methods to detect bioregions (modularity and map equation) with the conventional distance-based clustering method. We also explored the relationship between network and biodiversity metrics. For the analysis we used two datasets of iconic Australian plant groups at a continental scale, Acacia and eucalypts, as example groups. The modularity method detected fewer large bioregions produced the most succinct bioregionalisation for both plant groups corresponding to Australian biomes, while map equation detected many small bioregions including interzones at a natural scale of one. The clustering method was less sensitive than network methods in detecting bioregions. The network metric called participation coefficient from both network partition methods identified interzones or transition zones between bioregions. Furthermore, another network metric (betweenness) was highly correlated to richness and endemism. We conclude that the application of networks to biogeography offers a number of advantages and provides novel insights. More specifically, our study showed that these network partition methods were more efficient than the clustering method for bioregionalisation of continental-scale data in: 1) the identification of bioregions and 2) the quantification of biogeographic transition zones using the participation coefficient metric. The use of network methods and especially the participation coefficient metric adds to bioregionalisation by identifying transition zones which could be useful for conservation purposes and identifying biodiversity hotspots.
Layered calcareous deposits forming underground in caves, mines, and artificial channels present many opportunities for documenting changing Anthropocene environments. In cave systems, chemical signals are transmitted vertically from the exterior, but can be attenuated and delayed by soil and ecosystem processes. This applies to shifts in atmospheric radiocarbon and sulfur loading from hemispheric to global scales. Land-use changes are of more local significance, but δ¹³C can be a good indicator of deforestation and/or introduction of C4 vegetation. A wide variety of biomarkers, trace elements, and isotope ratios show specific responses to environmental disturbance, including the addition of pollutants.
The authors would like to correct several errors published in J. Exp. Biol. 212, 1859-1868.
In Table 2, the reported values of oxygen consumption rate at 10°C and 3°C were too high by a factor of 60. The correct values are presented below in a corrected Table 2. These errors did not affect either the statistical results or the Q10 values presented in Table 2. As the differences in oxygen consumption rates between 10°C and 3°C are discussed only from the Q10 values, these errors do not have consequences for the results and discussion presented in the paper.
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Table 2. Mean oxygen consumption rate and Q10 values for the seven populations of the subterranean crustacean N. rhenorhodanensis for a temperature range of 10°C to 3°C
The authors apologize for these errors but assure readers that the results and conclusions of the original paper remain unchanged.
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Giovanni Badino: Underground meteorology - "What's the weather underground?" The aim of this work is to provide a synthetic outline of some of the processes of transient nature occurring in caves, focusing on poorly studied general aspects of underground physics and mainly making use of original experimental data. In the first part, the average climatic conditions of a caves, their connection to the external climate, and the general role played by rock, water, air and external morphology are discussed. The variation of the internal temperature with the altitude is a key parameter for the cave physics: the related energetic consequences are briefly discussed. In the second part, transient processes are considered, and a general overview of main meteorological phenomena occurring underground is given. The physics of thermal sedimentation, of underground temperature ranges, of infrasonic oscillations of cave atmospheres and, above all, of water vapour condensation in caves is synthetically described. The experimental study of these processes is extremely difficult, because they are time dependent and have very small amplitude; the first measurements show, however, that their variability from one cave to another, and from point to point inside a cave, is surprisingly high. To provide a more correct interpretation of underground climatic measurements, for their speleogenetic role and importance in cave environment protection, a better understanding of the processes described here is essential.
Speleothems (mineral deposits that formed in caves) are currently giving us some of the most exciting insights into environments and climates during the Pleistocene ice ages and the subsequent Holocene rise of civilizations. The book applies system science to Quaternary environments in a new and rigorous way and gives holistic explanations the relations between the properties of speleothems and the climatic and cave setting in which they are found. It is designed as the ideal companion to someone embarking on speleothem research and, since the underlying science is very broad, it will also be invaluable to a wide variety of others. Students and professional scientists interested in carbonate rocks, karst hydrogeology, climatology, aqueous geochemistry, carbonate geochemistry and the calibration of climatic proxies will find up-to-date reviews of these topics here. The book will also be valuable to Quaternary scientists who, up to now, have lacked a thorough overview of these important archives. Additional resources for this book can be found at: www.wiley.com/go/fairchild/speleothem.
Obligatory cavernicoles, or troglobites, have traditionally been of special interest to evolutionary biologists for several reasons. The existence of animal life in caves and other subterranean spaces at first attracted attention because of its novelty; intensive biological exploration of caves began little more than a century ago. Although the discovery and description of the cave faunas of the world is far from complete, especially in the Western Hemisphere, so much descriptive information has been compiled that we can safely assert that, at least in unglaciated, temperate parts of the world, the occurrence of numerous species of troglobites in any major limestone region is a common and highly probable phenomenon.