39 Ar dating of cave ice combined with pollen, cryogenic calcite, and radiocarbon analyses reveals late Little Ice Age origin (Leupa Cave, SE Alps)

Screening of 1,000-years old ice layers from the perennial ice block of Scărișoara Ice Cave (NW Romania) revealed the presence of fungal communities. Using culture-dependent methods and molecular techniques based on DGGE fingerprinting of 18S rRNA gene fragments and sequencing, we identified 50 cultured and 14 uncultured fungi in presently-forming, 400 and 900 years old ice layers, corresponding to 28 distinct operational taxonomic units (OTUs). The dominant ice-contained fungal OTUs were related to Ascomycota, Basidiomycota and Cryptomycota phyla. Representatives of Mucoromycota and Chytridiomycota were also isolated from recent and 400 years old ice samples. The cryophilic Mrakia stokesii was the most abundant fungal species found in the cave ice samples of all prospected ages, alongside other cryophilic fungi also identified in various glacial environments. Ice deposits formed during the Little Ice Age (dated between AD 1,250 and 1,850) appeared to have a higher fungal diversity than the ice layer formed during the Medieval Warm Period (prior to AD 1,250). A more complex fungal community adapted to low temperatures was obtained from all analyzed ice layers when cultivated at 4 °C as compared to 15 °C, suggesting the dominance of cold-adapted fungi in this glacial habitat. The fungal distribution in the analyzed cave ice layers revealed the presence of unique OTUs in different aged-formed ice deposits, as a first hint for putative further identification of fungal biomarkers for climate variations in this icy habitat. This is the first report on fungi from a rock-hosted cave ice block.

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 cave 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 cave 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 cave type, especially in regard 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.

BIOGEOGRAPHIA — vol. XI/I - 1987 Biogeografia delle Alpi Sud«OrienraIi Molluschi terrestri ‘delle Alpi sudorientali ALBERTA BOATO, MARCO BODON, M. MANUELA GIOVANNELLI, . PAUL MILDNER Dz&#39;p¢zrz‘imem‘o di Biologia, Um&#39;verrz&#39;tz2 dz&#39; Pzzdova Istzmto di Zoologzkz, Um&#39;ver5z&#39;z‘oi di Siemz Mureo Friulzmo dz’ Storm Ncztzzmle, Udirze Lmzdermureum fiir Kt&#39;z’rm‘en, Klagenfim‘ SUMMARY The research, carried out in the years 1978-1987, concerns the terrestrial Prosobranchia and Pulmo- nata from the southeastern Alps, in which the whole Friuli region, the Isonzo Valley and the Carso Triestino are included. Results are presented as a species list (202 species), where for each taxon are provided: quotations from literature, with synonyms; sampling localities; unpublished records from mu- seum collections, if relevant; range; notes on taxonomic problems and distribution. A critical list of taxa of doubtful presence in the area, or uncertain taxonomic position is also provided. For the biogeographical analysis, the southeastern Alps were divided in three subareas: Carnic Low- land, Prealps and Alps (west of the Fella-Tagliamento riverine systems); Julian Lowland, Prealps and Alps (east of the Fella-Tagliamento line, including the Isonzo Valley); Carso Triestino. The binary (pre- sence-absence) Sorensen similarity index has been evaluated for all possible comparisons between the species lists, of following areas: the southeastern Alps (considered as a whole); the three sub—areas (Carnic Alps, Julian Alps, Carso); the central-western Slovenia; the southern Carinthia; the Istrian peninsula; the Venato. The relative percentage of the chorological components of the above cited areas are also com- pare . As far as their terrestrial malacofauna is concerned, the southeastern Alps probably represent the richest italian region as to species number. As species presence-absence, SE Alps as a whole display their highest similarity with the Veneto, and then with Istria, while Carinthia and Slovenia cluster together. In their chorological composition, SE Alps appear to be rather heterogeneous: in fact, in the Julian Alps and in the Carso Triestino the Dinaric and Balcanic components, more xerotetmophilic, are prevailing; species with this type of distribution reach very often the northern and western edges of their range in corre spondence of Isonzo or Tagliamento rivers. Ln contrast, in the Carnic Alps the E-Alpine-Carpathic com- ponent is strongly represented. Species with this type of distribution are linked to cool habitats and were probably arrived in SE Alps from the mountains of southeastern Europe, being favoured by the oceanic climate and continuity of mountain systems. Moreover, in SE Alps, the fauna is enriched by the presence of several endemic species, which presence is probably related to the refuge center role played by this region during the Pleistocene glacial periods, and by the occurrence of several cave habitats. INTRODUZIONE Come «E state piu volte ribadito da molti, ed in particolare da La Greca (1964, 1975), una ricerca biogeografica non puo dare risultati attendibili se non e fondata su taxa ben definiti e dei quali sia anche esaurientemente conosciuta la distribuzione geografica. Queste condizioni, purtroppo, non si possono dire pienarnente soddisfatte per quanto concerne i molluschi terrestri, sui qualj spesso mancano revisioni svolte secondo moderni criteri tassonomici o cornunque secondo metodologie 429

Ice entrenched microcosm represents a vast reservoir of novel species and a proxy for past climate reconstitution. Among glacial ecosystems, ice caves represent one of the scarcely investigated frozen habitats. To characterize the microbial diversity of perennial ice from karst ecosystems, Roche 454 sequencing of 16S rRNA gene amplicons from the underground ice block of Scarisoara Ice Cave (Romania) was applied. The temporal distribution of bacterial and archaeal community structures from newly formed, 400, and 900 years old ice layers was surveyed and analyzed in relation with the age and geochemical composition of the ice substrate. The microbial content of cave ice layers varied from 3.3 104 up to 7.5 105 cells mL−1, with 59–78% viability. Pyrosequencing generated 273,102 reads for the five triplicate ice samples, which corresponded to 3,464 operational taxonomic units (OTUs). The distribution of the bacterial phyla in the perennial cave ice varied with age, organic content, and light exposure. Proteobacteria dominated the 1 and 900 years old organic rich ice deposits, while Actinobacteria was mostly found in 900 years old ice strata, and Firmicutes was best represented in 400 years old ice. Cyanobacteria and Chlorobi representatives were identified mainly from the ice block surface samples exposed to sunlight. Archaea was observed only in older ice strata, with a high incidence of Crenarchaeota and Thaumarchaeaota in the 400 years old ice, while Euryarchaeota dominated the 900 years old ice layers, with Methanomicrobia representing the predominant taxa. A large percentage (55.7%) of 16S rRNA gene amplicons corresponded to unidentified OTUs at genus or higher taxa levels, suggesting a greater undiscovered bacterial diversity in this glacial underground habitat. The prokaryotes distribution across the cave ice block revealed the presence of 99 phylotypes specific for different ice layers, in addition to the shared microbial community. Ice geochemistry represented an important factor that explained the microbial taxa distribution in the cave ice block, while the total organic carbon content had a direct impact on the cell density of the ice microcosm. Both bacterial and archaeal community structures appeared to be affected by climate variations during the ice formation, highlighting the cave ice microbiome as a source of putative paleoclimatic biomarkers. This report constitutes the first high-throughput sequencing study of the cave ice microbiome and its distribution across the perennial underground glacier of an alpine ice cave.

Our understanding of the icy-habitat microbiome is likely limited by a lack of reliable data on microorganisms inhabiting underground ice that has accumulated inside caves. To characterize how environmental variation impacts cave ice microbial community structure, we determined the composition of total and potentially active bacterial communities along a 13,000-year-old ice core from Scarisoara cave (Romania) through 16S rRNA gene Illumina sequencing. An average of 2,546 prokaryotic gDNA operational taxonomic units (OTUs) and 585 cDNA OTUs were identified across the perennial cave ice block and analyzed in relation to the geochemical composition of ice layers. The total microbial community and the putative active fraction displayed dissimilar taxa profiles. The ice-contained microbiome was dominated by Actinobacteria with a variable representation of Proteobacteria, while the putative active microbial community was equally shared between Proteobacteria and Firmicutes. Accordingly, a major presence of Cryobacterium, Lysinomonas, Pedobacter, and Aeromicrobium phylotypes homologous to psychrotrophic and psychrophilic bacteria from various cold environments were noted in the total community, while the prevalent putative active bacteria belonged to Clostridium, Pseudomonas, Janthinobacterium, Stenotrophomonas, and Massilia genera. Variation in the microbial cell density of ice strata with the dissolved organic carbon (DOC) content and the strong correlation of DOC and silicon concentrations revealed a major impact of depositional processes on microbial abundance throughout the ice block. Post-depositional processes appeared to occur mostly during the 4,000–7,000 years BP interval. A major bacterial composition shift was observed in 4,500–5,000-year-old ice, leading to a high representation of Beta- and Deltaproteobacteria in the potentially active community in response to the increased concentrations of DOC and major chemical elements. Estimated metabolic rates suggested the presence of a viable microbial community within the cave ice block, characterized by a maintenance metabolism in most strata and growth capacity in those ice deposits with high microbial abundance and DOC content. This first survey of microbial distribution in perennial cave ice formed since the Last Glacial period revealed a complex potentially active community, highlighting major shifts in community composition associated with geochemical changes that took place during climatic events that occurred about 5,000 years ago, with putative formation of photosynthetic biofilms.

Cave ice ecosystems represent a poorly investigated glacial environment. Diversity of cave ice bacteria and their distribution in perennial ice deposits of this underground glacial habitat could constitute a proxy for microbial response to climatic and environmental changes. Scarisoara Ice Cave (Romania) hosts one of the oldest and largest cave ice blocks worldwide. Here we report on cultured microbial diversity of recent, 400, and 900 years-old perennial ice from this cave, representing the first characterization of a chronological distribution of cave-ice bacteria. Total cell density measured by SYBR Green I epifluorescence microscopy varied in the 2.4 x 104 – 2.9 x 105 cells mL-1 range. The abundance of cultured bacteria (5 x 102 – 8 x 104 CFU mL-1) representing 0.3-52% of the total cell number decreased exponentially with the ice age, and was higher in organic rich ice sediments. Cultivation at 4˚C and 15˚C using BIOLOG EcoPlates revealed a higher functional diversity of cold-active bacteria, dependent on the age, sediment content and physicochemical properties of the ice. The composition dissimilarity of ice microbiota across the ice block was confirmed by growth parameter variations when cultivated in different liquid media at low and high temperatures. PCR-DGGE and sequencing of bacterial 16S rRNA gene fragments from the cultured ice samples led to the identification of 77 bacterial amplicons belonging to Gammaproteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria, showing variation in distribution across the ice layers. Several identified OTUs were homologous to those identified in other glacial and karst environments and showed partial conservation across the ice block. Moreover, our survey provided a glimpse on the cave-ice hosted bacteria as putative biomarkers for past climate and environmental changes.

Chapter 19 - Ice Caves in Italy

Chapter 25 - Ice Caves in Romania

Abstract. The paleoclimatic significance of the perennial ice deposit in Scărişoara Ice Cave has been remarked on since the early 20th century, but a lack of understanding of the processes involved in the genesis, age and long-term dynamics and volume fluctuations of ice hampered all attempts to extract valuable data on past climate and vegetation changes. In this paper, we present a model of ice genesis and dynamics, based on stable isotopes, ice level monitoring (modern and archived) and radiocarbon dating of organic matter found in the ice. Ice in this cave mostly consists of layers of lake ice, produced as liquid water freezes from top to bottom in mid-autumn, and floor ice, produced as inflow water in winter freezes on top of the lake ice. This mechanism was also acting in the past, during the Medieval Warm Period and the Little Ice Age. The ice block is not stable in shape and volume, being continuously modified by ablation on top and sides, basal melting and lateral flow. Radiocarbon dating shows that the ice block is older than 1000 years, but ice flow and differential basal melting suggesting that the ice could be much older.

&amp;lt;p&amp;gt;Since the first core drilled in a cave ice deposit in 1947, more than 141 m of ice cores has been extracted from 20 cave ice deposits worldwide until 2021. Cave ice drilling projects focused mainly in Central European caves, however, half of the cave ice cores (3 out of 6) published in 2020 represent non-European localities predicts that an increasing number of such projects are focusing on other geographical areas hosting ice caves. Depending on the two types of ice encountered (firnified snow and frozen water), local climatic conditions and cave geometry, cave ice cores have highly variable length (between 1 and 25 m long), time span and continuity of the record covered (from a few years up to several thousands of year). The longest cave ice core in terms of both core length (~25&amp;amp;#160;m) and continuous time span (~10 kyr) comes from Sc&amp;amp;#259;ri&amp;amp;#537;oara Ice Cave (Romania), with several others (in Spain, Slovakia, Austria, Romania, the USA) reaching back in time towards (and beyond) the mid-Holocene. Major challenges in cave ice core science are posed by 1) presence of englacial rocky and woody debris, 2) complex stratigraphy of the ice deposits (often disturbed due to ice flow in a restricted space), 3) problematic chronology and 4) complex mechanisms of climate-proxy information transfer. Regardless, cave ice deposits offered over the past decade several unique records of Holocene climate and environmental change as well as of past microbial and fungal diversity. Because ice caves are located at much lower altitudes and latitudes than polar and mountain glaciers, they face the double threat of both increasing temperatures and precipitation amounts, several possible milennial old deposits being lost over the past few years. An ongoing race to salvage the paleoclimatic information these ice deposits holds is thwarted by climatic, financial and knowledge risks.&amp;lt;/p&amp;gt;

Controversy regarding the age and origin of deposits of massive ice in high altitude caves has existed for almost a century. Some writers believe that the ice has formed during postglacial time, while others suggest glacial origins for the ice. Caves falling into the latter category are commonly at high altitudes in recently glaciated or periglacial regions. Two cases illustrating crystallographic and isotopic techniques used in the study of cave ice are described from western Canada. In one case a vertical wall of ice completely blocks passages in a high attitude cave. In the other case two caves situated in a low altitude lava flow, which has been dated by radiocarbon analysis, are blocked by horizontal ice. The summary discusses the similarities in the ice crystallography of the caves and points out that the terms fossil and glacial ice must be severely restricted when describing cave ice deposits.

Frozen water is the most widespread type of ice present in ice caves and forms ice stalagmites and stalactites as well as floor ice, which is often several meters thick. Organic macroremains are commonly rare in this type of cave ice, which makes it difficult to establish a chronology and severely limits the use of such ice deposits as paleoenvironmental archives. Here, the chronology of such ice deposits in the inner part of the glaciated Eisriesenwelt, one of the world’s largest ice caves located in the European Alps of Austria, is determined by a combination of radiocarbon and 230Th dating of cryogenic calcite. The data suggest that this cave ice has formed over the last three millennia, with a marked increase in the average accumulation rate during the thirteenth century, coinciding with the onset of the Little Ice Age in the Alps. Data from a second site closer to the entrance suggests that large parts of this tourist cave were likely ice-free during the Medieval Warm Period and that a substantial part of the ice is probably a relic of the Little Ice Age. The current warming has already penetrated deeper into the cave than during the Medieval Warm Period, although air exchange during the warm season is restricted by a door at the cave entrance.

The Triglav Glacier in the Julian Alps and the Skuta Glacier in the Kamnik-Savinja Alps are among the south-easternmost glaciers in the Alps. Historical data show that ice masses are undergoing mass loss as the overall climate warms. Glacier ice and cave ice contain a wealth of paleoclimatic information, and rapid sampling is needed if any such information is to be saved before the ice is completely melted. We present the first comprehensive geochemical and water isotope data from glacier ice, meltwater, spring water, and cave ice in the Mount Triglav area and glacier ice from the Skuta Glacier. The samples primarily reflect the initial precipitation signal that has been greatly modified by the input of local CaCO3-rich dust with lesser amounts of marine aerosol and vegetation debris.

Two 2 m long ice cores (BA and BB) were extracted from the floor ice of Borştig Ice Cave in December 2005. Below a co-existing dust horizon (~13 cm underneath the 10 December 2005 ice surface) neither core presented any sign of hiatus, so the ice deposition is considered to be continuous. Tritium concentration of 94 samples from a 1.85 m long ice section were analysed by liquid scintillation counting technique. Samples from the lower 0.33 m of the sequence did not contain tritium above the critical level (7.2 TU). The highest value of tritium content (166.4±4.0 TU) was found at ~96 cm below the surface. This salient value is considered to be synchronous with the climax of tritium concentration in the Northern Hemisphere's atmospheric precipitation (1963). Beside this characteristic global radiochemical marker event, minor events were also detected, and dated (ie, 1954, 1958 and 1975) by corresponding peaks in the tritium concentration record of BB ice core to peaks of an estimation of tritium activity of past precipitation at Borştig Ice Cave location. The estimation was based on a data set from four nearby stations of the Global Network of Isotopes in Precipitation. The highest annual accumulation rate (6.74 cm/yr) was between 1958 and 1963 and gradually decreased to 0.54 cm/yr for the recent decades. The mean ice accumulation rate was 4.34 cm/yr over the 1954—1986 period. The estimated age at the bottom of the 21 m thick ice block assuming constant accumulation is roughly 500 years.

ABSTRACTThis survey presents the first high-throughput characterisation of fungal distribution based on ITS2 Illumina sequencing of uncultured microbiome from a 1500 years old perennial ice deposit in Scărișoara Ice Cave, Romania. Of the total of 1 751 957 ITS2 sequences, 64% corresponded to 182 fungal operational taxonomic units, showing a low diversity, particularly in older ice strata, and a distinct temporal distribution pattern. Ascomycota was the major phylum in all ice samples, dominating the 400 and 1500 years old ice strata deposited during the cold Little Ice Age (LIA) and Dark Ages Cold Period, while Basidiomycota was mostly present in 900-years old ice formed during the Medieval Warm Period (MWP). Chytridiomycota and Mucoromycota phyla were present in recently formed and 400-years old ice, respectively. Among the 80 identified genera,Cryptococcus victoriae, commonly found in glacial habitats, was identified in all strata. A positive correlation between fungal distribution and ice conductivity, Ca, Na and Sr concentrations was observed across the ice block, with pH values trailing climate variations during LIA and MWP, respectively. Our record highlighted the presence of a complex climate and environmental-driven fungal community in perennial ice strata accumulated during the last 1500 years in Scărișoara Ice Cave.