scholarly journals A hole in the nematosphere: tardigrades and rotifers dominate the cryoconite hole environment, whereas nematodes are missing

2020 ◽  
Author(s):  
K. Zawierucha ◽  
D. L. Porazinska ◽  
G. F. Ficetola ◽  
R. Ambrosini ◽  
G. Baccolo ◽  
...  
Keyword(s):  
Cryoconite Hole

scholarly journals Cryoconite hole connectivity on the Wright Lower Glacier, McMurdo Dry Valleys, Antarctica

2016 ◽  
Vol 62 (234) ◽  
pp. 714-724 ◽  
Author(s):  
SHELLEY MACDONELL ◽  
MARTIN SHARP ◽  
SEAN FITZSIMONS
Keyword(s):  
Spatial Variability ◽  
Drainage System ◽  
Chloride Content ◽  
Mcmurdo Dry Valleys ◽  
Hydrological Connectivity ◽  
Dry Valleys ◽  
Near Surface ◽  
Cryoconite Hole ◽  
Transfer Method ◽  
Surface Ice

ABSTRACTCryoconite holes can be important sources and stores of water and nutrients on cold and polythermal glaciers, and they provide a habitat for various forms of biota. Understanding the hydrological connectivity of cryoconite holes may be the key to understanding the transport of nutrients and biological material to the proglacial areas of such glaciers. This paper aims to characterize and explain spatial variability in the connectivity of ice-lidded cryoconite holes on a small, piedmont glacier in the McMurdo Dry Valleys through geochemical analysis of cryoconite hole waters. Solute concentrations in both surface and near-surface ice and cryoconite holes, vary greatly along the glacier centerline, and all sample types displayed similar spatial patterns of variability. Using chloride as a tracer, we estimated variations in cryoconite hole connectivity along the glacier centerline. We found that a previously used mass transfer method did not provide reliable estimates of the time period for which cryoconite hole waters had been isolated from the atmosphere. We attribute this to spatial variability in both the chloride content of the surface ice and surface ablation rates. The approach may, however, be used to qualitatively characterize spatial variations in the hydrological connectivity of the cryoconite holes. These results also suggest that ice-lidded cryoconite holes are never truly isolated from the near-surface drainage system.

scholarly journals Dissolved organic nutrients dominate melting surface ice of the Dark Zone (Greenland Ice Sheet)

2019 ◽  
Vol 16 (16) ◽  
pp. 3283-3296 ◽  
Author(s):  
Alexandra T. Holland ◽  
Christopher J. Williamson ◽  
Fotis Sgouridis ◽  
Andrew J. Tedstone ◽  
Jenine McCutcheon ◽  
...  
Keyword(s):  
Organic Phase ◽  
Stream Water ◽  
Inorganic Nitrogen ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Western Coast ◽  
Ice Surface ◽  
Cryoconite Hole ◽  
Melting Surface ◽  
Surface Ice

Abstract. Glaciers and ice sheets host abundant and dynamic communities of microorganisms on the ice surface (supraglacial environments). Recently, it has been shown that Streptophyte glacier algae blooming on the surface ice of the south-western coast of the Greenland Ice Sheet are a significant contributor to the 15-year marked decrease in albedo. Currently, little is known about the constraints, such as nutrient availability, on this large-scale algal bloom. In this study, we investigate the relative abundances of dissolved inorganic and dissolved organic macronutrients (N and P) in these darkening surface ice environments. Three distinct ice surfaces, with low, medium and high visible impurity loadings, supraglacial stream water and cryoconite hole water, were sampled. Our results show a clear dominance of the organic phase in all ice surface samples containing low, medium and high visible impurity loadings, with 93 % of the total dissolved nitrogen and 67 % of the total dissolved phosphorus in the organic phase. Mean concentrations in low, medium and high visible impurity surface ice environments are 0.91, 0.62 and 1.0 µM for dissolved inorganic nitrogen (DIN), 5.1, 11 and 14 µM for dissolved organic nitrogen (DON), 0.03, 0.07 and 0.05 µM for dissolved inorganic phosphorus (DIP) and 0.10, 0.15 and 0.12 µM for dissolved organic phosphorus (DOP), respectively. DON concentrations in all three surface ice samples are significantly higher than DON concentrations in supraglacial streams and cryoconite hole water (0 and 0.7 µM, respectively). DOP concentrations are higher in all three surface ice samples compared to supraglacial streams and cryoconite hole water (0.07 µM for both). Dissolved organic carbon (DOC) concentrations increase with the amount of visible impurities present (low: 83 µM, medium: 173 µM and high: 242 µM) and are elevated compared to supraglacial streams and cryoconite hole water (30 and 50 µM, respectively). We speculate that the architecture of the weathering crust, which impacts on water flow paths and storage in the melting surface ice and/or the production of extracellular polymeric substances (EPS), containing both N and P in conjunction with C, is responsible for the temporary retention of DON and DOP in the melting surface ice. The unusual presence of measurable DIP and DIN, principally as NH4+, in the melting surface ice environments suggests that factors other than macronutrient limitation are controlling the extent and magnitude of the glacier algae.

scholarly journals Seasonal changes of ice surface characteristics and productivity in the ablation zone of the Greenland Ice Sheet

2015 ◽  
Vol 9 (2) ◽  
pp. 487-504 ◽  
Author(s):  
D. M. Chandler ◽  
J. D. Alcock ◽  
J. L. Wadham ◽  
S. L. Mackie ◽  
J. Telling
Keyword(s):  
Remote Sensing ◽  
Surface Albedo ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Surface Characteristics ◽  
Biological Processes ◽  
Ablation Zone ◽  
Ice Surface ◽  
Surface Productivity ◽  
Cryoconite Hole

Abstract. Field and remote sensing observations in the ablation zone of the Greenland Ice Sheet have revealed a diverse range of ice surface characteristics, primarily reflecting the variable distribution of fine debris (cryoconite). This debris reduces the surface albedo and is therefore an important control on melt rates and ice sheet mass balance. Meanwhile, studies of ice sheet surface biological processes have found active microbial communities associated with the cryoconite debris, which may themselves modify the cryoconite distribution. Due to the considerable difficulties involved with collecting ground-based observations of the ice surface, our knowledge of the physical and biological surface processes, and their links, remains very limited. Here we present data collected at a field camp established in the ice sheet ablation zone at 67° N, occupied for almost the entire melt season (26 May–10 August 2012), with the aim of gaining a much more detailed understanding of the physical and biological processes occurring on the ice surface. These data sets include quadrat surveys of surface type, measurements of ice surface ablation, and in situ biological oxygen demand incubations to quantify microbial activity. In addition, albedo at the site was retrieved from AVHRR (Advanced Very High Resolution Radiometer) remote sensing data. Observations of the areal coverage of different surface types revealed a rapid change from complete snow cover to the "summer" (summer study period) ice surface of patchy debris ("dirty ice") and cryoconite holes. There was significant correlation between surface albedo, cryoconite hole coverage and surface productivity during the melt season, but microbial activity in "dirty ice" was not correlated with albedo and varied widely throughout the season. While this link suggests the potential for a remote-sensing approach to monitoring cryoconite hole biological processes, very wide seasonal and spatial variability in net surface productivity demonstrates the need for caution when extrapolating point measurements of biological processes to larger temporal or spatial scales.

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

2018 ◽  
Vol 59 (77) ◽  
pp. 1-9 ◽  
Author(s):  
Francesca Pittino ◽  
Maurizio Maglio ◽  
Isabella Gandolfi ◽  
Roberto Sergio Azzoni ◽  
Guglielmina Diolaiuti ◽  
...  
Keyword(s):  
Hot Spots ◽  
Bacterial Communities ◽  
Biological Activities ◽  
Meteorological Data ◽  
Rrna Gene ◽  
Ecological Communities ◽  
Italian Alps ◽  
Glacier Surface ◽  
Alpine Glacier ◽  
Cryoconite Hole

ABSTRACTCryoconite 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.

Absorption of solar energy in a cryoconite hole

1996 ◽  
Vol 23 (18) ◽  
pp. 2465-2468 ◽  
Author(s):  
Igor A. Podgorny ◽  
Thomas C. Grenfell
Keyword(s):  
Solar Energy ◽  
Cryoconite Hole

scholarly journals Bacterial community changes with cryoconite granule size and their susceptibility to exogenous nutrients on 10 glaciers in northwestern Greenland

2019 ◽  
Author(s):  
Jun Uetake ◽  
Naoko Nagatuska ◽  
Yukihiko Onuma ◽  
Nozomu Takeuchi ◽  
Hideaki Motoyama ◽  
...  
Keyword(s):  
Bacterial Community ◽  
Growth Process ◽  
Correlation Coefficients ◽  
Community Change ◽  
Early Growth ◽  
Granule Size ◽  
Filamentous Cyanobacterium ◽  
Glacier Ice ◽  
Cryoconite Hole ◽  
Exogenous Nutrients

AbstractCryoconite granules, which are dark-colored biological aggregates on glaciers, effectively accelerate the melting of glacier ice. Bacterial community varies with granule size, however, community change in space and their susceptibility to environmental factors has not been described yet. Therefore, we focused on bacterial community from 4 different granule sizes (30-249 μm, 250- 750 μm, 750-1599 μm, more than 1600 μm diameter) in 10 glaciers in northwestern Greenland and their susceptibility for exogenous nutrients in cryoconite hole. A filamentous cyanobacterium Phormidesmis priestleyi, which has been frequently reported from glaciers in Arctic was abundant (10-26%) across any size of granules on most of glaciers. Bacterial community across glaciers became similar with size increase, and whence smallest size fractions contain more unique genera in each glacier. Multivariate analysis suggests that phosphate, which is significantly higher in one glacier (Scarlet Heart Glacier), is primary associated with bacterial beta diversity. Correlation coefficients between abundance of major genera and nutrients largely changed with granule size, suggesting that nutrients susceptibility to genera changes with growth process of granule (e.g. P. priestleyi was affected by nitrate in early growth stage).

scholarly journals Observations of cryoconite hole system processes on an Antarctic glacier

2012 ◽  
Vol 85 (4) ◽  
pp. 393-407 ◽  
Author(s):  
SHELLEY A MACDONELL ◽  
SEAN J FITZSIMONS
Keyword(s):  
Cryoconite Hole

scholarly journals Island Biogeography of Cryoconite Hole Bacteria in Antarctica's Taylor Valley and Around the World

2018 ◽  
Vol 6 ◽  
Author(s):  
John L. Darcy ◽  
Eli M. S. Gendron ◽  
Pacifica Sommers ◽  
Dorota L. Porazinska ◽  
Steven K. Schmidt
Keyword(s):  
Island Biogeography ◽  
Taylor Valley ◽  
The World ◽  
Cryoconite Hole

scholarly journals Diversity and distribution of Tardigrada in Arctic cryoconite holes

2016 ◽  
Author(s):  
Krzysztof Zawierucha ◽  
Marta Ostrowska ◽  
Tobias R. Vonnahme ◽  
Miloslav Devetter ◽  
Adam P. Nawrot ◽  
...  
Keyword(s):  
Species Richness ◽  
Ice Sheets ◽  
Arctic Tundra ◽  
High Arctic ◽  
Svalbard Archipelago ◽  
The Status ◽  
Cryoconite Hole ◽  
Secondary Consumers ◽  
Arctic Glacier ◽  
Tundra Ecosystems

<p>Despite the fact that glaciers and ice sheets have been monitored for more than a century, knowledge on the glacial biota remains poor. Cryoconite holes are water-filled reservoirs on a glacier’s surface and one of the most extreme ecosystems for micro-invertebrates. Tardigrada, also known as water bears, are a common inhabitant of cryoconite holes. In this paper we present novel data on the morphology, diversity, distribution and role in food web of tardigrades on Arctic glaciers. From 33 sampled cryoconite holes of 6 glaciers on Spitsbergen, in 25 tardigrades were found and identified. Five taxa of Tardigrada (Eutardigrada) were found in the samples, they are: <em>Hypsibius dujardini</em>, <em>Hypsibius </em>sp. A, <em>Isohypsibius </em>sp. A., <em>Pilatobius</em> <em>recamieri</em>, and one species of Ramazzottiidae. <em>H. dujardini </em>and <em>P. recamieri</em> were previously known from tundra in the Svalbard archipelago. Despite the number of studies on Arctic tundra ecosystems, <em>Hypsibius</em> sp. A, one species of Ramazzottiidae and <em>Isohypsibius</em> sp. A are known only from cryoconite holes. Tardigrade found in this study do not falsify the hypothesis that glaciers and ice sheets are a viable biome (characteristic for biome organisms assemblages - tardigrades). Diagnosis of <em>Hypsibius</em> sp. A, <em>Isohypsibius</em> sp. A, and species of Ramazzottiidae with discussion on the status of taxa, is provided. To check what analytes are associated with the presence of tardigrades in High Arctic glacier chemical analyses were carried out on samples taken from the Buchan Glacier. pH values and the chemical composition of anions and cations from cryoconite hole water from the Buchan Glacier are also presented. The current study on the Spitsbergen glaciers clearly indicates that tardigrade species richness in cryoconite holes is lower than tardigrade species richness in Arctic tundra ecosystems, but consists of unique cryoconite hole species. As cryoconite tardigrades may feed on bacteria as well as algae, they are primary consumers and grazers - secondary consumers of the decomposer food chain in this extreme ecosystem. </p>

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