Turkish glacier inventory and classification from high-resolution satellite data

In view of the rapid and accelerating glacier retreat observed worldwide, the creation of an updated glacier inventory is fundamental to understand the glacier changes. Here we present the Turkish glacier inventory based on recent high-resolution satellite images (Pleiades, Google Earth\u2122 and SPOT images). Outlines are manually digitized in ArcMap software. We identified 51 glaciers covering 12.29 km2: more than 60% of the Turkish glacierized area is located on Mount Ararat where the ice cap and four small outlet glaciers cover 7.37 km2. Turkish glaciation is characterized by small glaciers or glacierets partly debris-covered: only three glaciers (Erin\ue7, Izb\u131rak and Ararat glaciers) are larger than 0.5 km2. To assess the evolution of glaciers, we have focused on Mount Ararat where we digitized outlines for 1990, 1994, 2000 and 2016: in 26 years considered the glacier shows a retreat of 2.99 km2, 12 29% of the initial value, showing a reduction rate dramatically higher than the main glacierized mountain ranges of the world

THE DARK SIDE OF THE ICE: GLACIOLOGICAL AND BIOLOGICAL ASPECTS OF SUPRAGLACIAL DEBRIS

This research deals with a multi-disciplinary analysis of the supraglacial debris. Debris significantly influences the evolution of glacier surface, its energy balance, and the carbon fluxes and storage. In this work through a multi-disciplinary approach, we focused on this dark side of the glaciers from two different points of view: the glaciological and the biological one. In the last decades, the large majority of glaciers, including those on the Italian Alps, showed a great increase of supraglacial debris cover. The analyses performed on aerial and UAVs imagery on a wide glacierized sector of Italy, highlighted that the debris-covered area doubled in the period 2003\u20132012, reaching an increase up to 30.10% of the whole glacier area. However, these changes in surface features, fed by an increased availability of debris, occurred with different patches, according to the physical properties of the bedrocks hosting the glaciers. This suggests that further studies are needed to quantify the occurrence and distribution of supraglacial debris on all the Italian glaciation. The ice albedo and, consequently, the energy balance of glaciers not only are affected by the presence or absence of a thick and continuous debris cover on the glacier surface, but also by the amount and distribution of the fine and sparse debris and dust that discontinuously cover glaciers. Sparse debris is thus important for determining the evolution of ice bodies, but its quantification is arduous, as the availability of high-resolution imagery, both from satellite and UAV, is mandatory. In this work we showed that the processing of an UAV image of the glacier through a segmentation approach allows describing ice features at a small-scale, including the distribution of fine debris. Moreover, we found evidence of darkening phenomena due to an increased amount of fine and sparse debris on the surface of glaciers. The darkening of glaciers is probably favoring organisms living in the supraglacial debris; however, organisms can promote glacier darkening because they produce dark matter (e.g. humic substances) and are themselves part of the dark debris quantified in glaciological analyses. A positive feedback seems therefore to occur on glacier surface, promoting the increase of supraglacial debris. The analyses of the life on supraglacial debris indicates that a glacier cannot be considered as an isolated environment, although it has different characteristics than the surrounding areas. Nematodes and Rotifers, for instance, can diffusely colonize supraglacial debris only in the presence of allochthonous organic matter, which represents the main source of organic carbon for these organisms in supraglacial environments where primary producers are scarce. Moreover, the study of bacterial communities in snow highlighted a possible contribution of organisms transported from the area where the air masses originated, as well as a non-negligible input of local air bacteria, maybe due to the deposition of local particulate during snowfall. This strong relation between glacier and ice-marginal environments is observable also from the bacterial community of the cryoconite holes. Indeed, we showed that ice-marginal environments may act as sources of bacteria for these micro habitats, but differences in environmental conditions limit the number of bacterial strains that may survive in them. At the same time, cryoconite holes host some organisms that were not found in any ice-marginal environment we sampled, thus suggesting that some bacteria may reach cryoconite from distant sources. These bacterial communities of cryoconite holes have a wide temporal evolution throughout an ablation season, with autotrophic Cyanobacteria populations dominating communities after snow melt, and heterotrophic populations increasing in abundance later in the season. The complex bacterial communities that inhabit glacier surface have large impacts on biogeochemical processes, in particular on the carbon cycle. In fact, we provided evidence for the occurrence in these environments of metabolic pathways that differ from those of oxygenic phototrophs and the respiration of heterotrophic organisms beforehand described on glacier surface. Indeed, we observed high abundance of heterotrophic anoxygenic phototrophs, suggesting that light might supplement the energy needed by the organisms permitting them to use some organic molecules as carbon sources. Furthermore, these communities could produce CO2 also by the oxidation of CO, which may be produced by photodegradation of organic matter present in the cryoconite. Finally, we investigated the fate of contaminants on the glaciers surface assessing a key role of the bacteria in the chlorpyrifos degradation. In summary, the results presented in this PhD thesis improved our knowledge of the supraglacial debris, its components and its evolution. The double view on the glacier system, both glaciological and biological, permits a deeper description of the mutual relations between bio and geo components

Atmospheric nitrogen deposition in a highly human impacted area in northern Italy

Nitrogen can enter the water cycle through atmospheric depositions on ground and water surfaces, leakages from point and diffuse sources (i.e., sewage treatment plants or sewage systems, fertilizer and manure applications), and erosion processes affecting nitrogen rich soils (EEA, 2005). However, integrating all nitrogen forms, processes and scales is still a major challenge for the understanding and the management of the nitrogen cycle

Water bears dominated cryoconite hole ecosystems : densities, habitat preferences and physiological adaptations of Tardigrada on an alpine glacier

We investigated the Forni Glacier and the surrounding area in the Alps in terms of habitat preferences, densities, dispersal and desiccation tolerance of glacier tardigrades, which are one of the most common faunal representatives and top consumers in supraglacial ecosystems. To do so, we sampled supraglacial environments (cryoconite holes, debris from ice surface, dirt cones and moraine, mosses from supraglacial stones) and non-glacial habitats (mosses, freshwater sediments and algae), and we installed air traps on the glacier and the nearby area. We found that cryoconite holes on the Forni Glacier are exclusively dominated by one metazoan group of tardigrades, representing one species, Hypsibius klebelsbergi (identified by morphological and molecular approaches). Tardigrades were found in 100% of cryoconite holes and wet supraglacial sediment samples and reached up to 172 ind./ml. Additionally, we found glacier tardigrades in debris from dirt cones and sparsely in supraglacial mosses. Glacier tardigrades were absent from freshwater and terrestrial samples collected from non-glacial habitats. Despite the fact that H. klebelsbergi is a typical aquatic species, we showed it withstands desiccation in sediments, but in low temperatures only. Treatments conducted in higher temperatures and water only showed low or no recovery. We suspect successful dispersal with wind might have taken place only when tardigrades desiccated in sediments and were passively transported by cold wind. Limited ability to withstand high temperatures and desiccation may be potential barriers preventing glacier tardigrades inhabiting new, even apparently suitable high mountain water bodies like temporary rock pools

Post-Depositional Biodegradation Processes of Pollutants on Glacier Surfaces

Glaciers are important fresh-water reservoirs for our planet. Although they are often located at high elevations or in remote areas, glacial ecosystems are not pristine, as many pollutants can undergo long-range atmospheric transport and be deposited on glacier surface, where they can be stored for long periods of time, and then be released into the down-valley ecosystems. Understanding the dynamics of these pollutants in glaciers is therefore important for assessing their environmental fate. To this aim, it is important to study cryoconite holes, small ponds filled with water and with a layer of sediment, the cryoconite, at the bottom, which occur on the surface of most glaciers. Indeed, these environments are hotspots of biodiversity on glacier surface as they host metabolically active bacterial communities that include generalist taxa able to degrade pollutants. In this work, we aim to review the studies that have already investigated pollutant (e.g., chlorpyrifos and polychlorinated-biphenyls (PCBs)) degradation in cryoconite holes and other supraglacial environmental matrices. These studies have revealed that bacteria play a significant role in pollutant degradation in these habitats and can be positively selected in contaminated environments. We will also provide indication for future research in this field

Nematodes and rotifers on two Alpine debris-covered glaciers

Debris-covered glaciers (DCGs) are glaciers whose ablation area is mostly covered by a continuous layer of debris, and are considered to be among the continental glacierized environments richest in life. DCG colonization by microorganisms, plants and animals, has been investigated in a few studies, while the meiofauna (metazoans smaller than 2\uc2\ua0mm) of these environments has been neglected so far. In this study, we analyzed nematode and rotifer fauna on the two largest debris-covered glaciers of the Italian Alps: the Miage Glacier and the Belvedere Glacier. In total, we collected 38 debris samples on the glaciers in July and September 2009. All the rotifers we found belonged to the bdelloid Adineta vaga (Davis, 1873). Nematodes belonged to 19 species. Miage Glacier hosted a richer and more diverse nematode fauna than the Belvedere. The dominant genus was Plectus Bastian, 1865, a common genus in habitats at high latitude and altitude. Analysis of the feeding type of nematodes highlighted that bacterivores were dominant on Miage Glacier, while bacterivores and herbivores were more widespread on Belvedere Glacier. Predator nematodes were absent. Analysis of the food-web structure indicated that nematode assemblages on both glaciers were typical of environments with depleted food availability, probably resulting from instability of the glacier surface and the short exposure of sediments, preventing the evolution of true soil and enrichment in organic matter of the debris. The scarcity of bacterial primary producers suggests that deposition of allochthonous organic matter is the principal organic carbon source in this environment

Recent structural evolution of forni glacier tongue (Ortles-Cevedale Group, Central Italian Alps)

Structural glaciology yields important details about the evolution of glacier dynamics in response to climate change. The maps provided here document the occurrence and evolution of brittle and ductile structures on the tongue of Forni Glacier, Ortles-Cevedale Group, Central Italian Alps, between 2003 and 2014. Through the remote sensing-based analysis of structures, we found evidence of brittle fractures such as crevasses, faults and ring faults, and ductile structures such as ogives at the base of the icefall in the eastern glacier tongue. Although each of the three glacier tongues have evolved differently, a reduction in flow-related dynamics and an increase in the number of collapse structures occurred over the study period. Analysis of the glacier structural evolution based on the numbers and the locations of different structures, suggest a slowdown of glacier flow on the eastern tongue. The recent evolution of the glacier also suggests that the occurrence of a disintegration scenario is likely to worsen over the next decades

Bacterial communities of cryoconite holes of a temperate alpine glacier show both seasonal trends and year-to-year variability

Cryoconite holes are small depressions of the glacier surface filled with melting water and with a wind-blown debris on the bottom. These environments are considered hot spots of biodiversity and biological activities on glaciers and host communities dominated by bacteria. Most of the studies on cryoconite holes assume that their communities are stable. However, evidence of seasonal variation in cryoconite hole ecological communities exists. We investigated the variation of the bacterial communities of cryoconite holes of Forni Glacier (Central Italian Alps) during the melting seasons (July-September) 2013 and 2016, for which samples at three and five time-points, respectively were available. Bacterial communities were characterized by high-throughput Illumina sequencing of the hypervariable V5'V6 regions of 16S rRNA gene, while meteorological data were obtained by an automatic weather station. We found consistent trends in bacterial communities, which shifted from cyanobacteria-dominated communities in July to communities dominated by heterotrophic orders in late August and September. Temperature seems also to affect seasonal dynamics of communities. We also compared bacterial communities at the beginning of the melting season across 4 years (2012, 2013, 2015 and 2016) and found significant year-to-year variability. Cryoconite hole communities on temperate glaciers are therefore not temporally stable

High-resolution mapping of glacier surface features. The UAV survey of the Forni Glacier (Stelvio National Park, Italy)

Fast, reliable and accurate methods for glacier mapping are necessary for understanding glacier dynamics and evolution and assessing their response to climate change. Conventional semi-automatic approaches are based on medium-resolution satellite images, but their use can cause significant loss of accuracy when analyzing small glaciers, which are predominant in the Alps. In this paper, we present a semi-automatic segmentation approach based on very high-resolution visible RGB images acquired from a UAV (Unmanned Aerial Vehicle) survey of the Fomi Glacier, in the Italian Alps, using an off-the-shelf digital camera. The method has the ability to map large-scale morphological features, i.e. bare ice and medial moraines, with better accuracy than methods relying on medium-resolution satellite imagery, with only slight misclassification at the margins. By using segmentation, we also mapped small-scale morphologies not discernible on satellite images, including epiglacial lakes and snow patches, in a semi-automatic way. On a small portion of the eastern ablation tongue, featuring homogeneous illumination conditions, we also investigated in finer detail the occurrence of fine and sparse debris and tested a texture filter technique for mapping crevasses, which showed promising results. Our analyses confirm that the glacier is undergoing intense dynamic processes, including darkening of the ablation tongue and increased surface instability, and show the potential of UAVs to revolutionize glaciological studies. We suggest that by using a combination of different payloads, mapping of glacier features via UAVs could reach high levels of accuracy and speed, making them useful tools for glacier inventories and geomorphological maps