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

Holland, Alexandra; Williamson, Christopher; Sgouridis, Fotis; Tedstone, Andrew; McCutcheon, Jenine; Cook, Joseph M.; Poniecka, Ewa; Yallop, Marian L.; Tranter, Martyn; Anesio, Alexandre M.

doi:10.5194/bg-16-3283-2019

Cited by 40 publications

(53 citation statements)

References 62 publications

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“…Second, DIP may not be as limiting in supraglacial environments as previously believed (Hodson et al, 2004;Stibal et al, 2008Stibal et al, , 2009, considering that DIN was consistently consumed during the present study when concentrations were artificially elevated. Such trends have also been reported in recent studies concerning both snow pack and surface ice environments, which suggested DIN to be in higher demand than DIP (Larose et al, 2013a;Holland et al, 2019). Overall, there is a clear response by the microbial community to all nutrient additions over the course of just 5-weeks in a cold, dark snow pack, indicating that the 24-h darkness and subfreezing temperatures of the polar winter may not be as limiting as previously thought.…”

Section: Varied Heterotrophic Community Response To Dissolved Nutriensupporting

confidence: 81%

Over Winter Microbial Processes in a Svalbard Snow Pack: An Experimental Approach

et al. 2020

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Snow packs cover large expanses of Earth's land surface, making them integral components of the cryosphere in terms of past climate and atmospheric proxies, surface albedo regulators, insulators for other Arctic environments and habitats for diverse microbial communities such as algae, bacteria and fungi. Yet, most of our current understanding of snow pack environments, specifically microbial activity and community interaction, is limited to the main microbial growing season during spring ablation. At present, little is known about microbial activity and its influence on nutrient cycling during the subfreezing temperatures and 24-h darkness of the polar winter. Here, we examined microbial dynamics in a simulated cold (−5 • C), dark snow pack to determine polar winter season microbial activity and its dependence on critical nutrients. Snow collected from Ny-Ålesund, Svalbard was incubated in the dark over a 5-week period with four different nutrient additions, including glacial mineral particles, dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP) and a combined treatment of DIN plus DIP. Data indicate a consumption of dissolved inorganic nutrients, particularly DIN, by heterotrophic communities, suggesting a potential nitrogen limitation, contradictory to phosphorus limitations found in most aquatic environments. 16S amplicon sequencing also reveal a clear difference in microbial community composition in the particulate mineral treatment compared to dissolved nutrient treatments and controls, suggesting that certain species of heterotrophs living within the snow pack are more likely to associate with particulates. Particulate phosphorus analyses indicate a potential ability of heterotrophic communities to access particulate sources of phosphorous, possibly explaining the lack of phosphorus limitation. These findings have importance for understanding microbial activity during the polar winter season and its potential influences on the abundance and bioavailability of nutrients released to surface ice and downstream environments during the ablation season.

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Section: Varied Heterotrophic Community Response To Dissolved Nutriensupporting

confidence: 81%

Over Winter Microbial Processes in a Svalbard Snow Pack: An Experimental Approach

et al. 2020

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“…Figure 2c also shows that the cryoconite and ice samples are distributed along two parallel directions. This suggests that a factor not investigated in this study (e. g. irradiation, pH, total organic carbon, nutrients concentration) may describe part of the unexplained variance of the algal community 51 . Given the complexity of the supraglacial environment, even the relatively low explained variance (i.e.…”

Section: Resultsmentioning

confidence: 89%

Glacier algae foster ice-albedo feedback in the European Alps

Mauro

Garzonio

Baccolo

et al. 2020

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the melting of glaciers and ice sheets is nowadays considered a symbol of climate change. Many complex mechanisms are involved in the melting of ice, and, among these processes, surface darkening due to organic material on bare ice has recently received attention from the scientific community. The presence of microbes on glaciers has been shown to decrease the albedo of ice and promote melting.Despite several studies from the Himalaya, Greenland, Andes, and Alaska, no quantitative studies have yet been conducted in the european Alps. in this paper, we made use of DnA sequencing, microscopy and field spectroscopy to describe the nature of glacier algae found at a glacier (Vadret da Morteratsch) of the European Alps and to evaluate their effect on the ice-albedo feedback. Among different algal species identified in the samples, we found a remarkable abundance of Ancylonema nordenskioeldii, a species that has never previously been quantitatively documented in the Alps and that dominates algal blooms on the Greenland ice Sheet. our results show that, at the end of the ablation season, the concentration of Ancylonema nordenskioeldii on the glacier surface is higher than that of other algal species (i.e. Mesotaenium berggrenii). Using field spectroscopy data, we identified a significant correlation between a reflectance ratio (750 nm/650 nm) and the algae concentration. This reflectance ratio could be useful for future mapping of glacier algae from remote sensing data exploiting band 6 (740 nm) and band 4 (665 nm) of the MultiSpectral Instrument (MSI) on board Sentinel-2 satellite. Here we show that the biological darkening of glaciers (i.e. the bioalbedo feedback) is also occurring in the european Alps, and thus it is a global process that must be taken into account when considering the positive feedback mechanisms related to glacier melting.Glaciers and ice sheets are not lifeless 1 . It has been demonstrated that several species of microorganisms, algae and small arthropods find their optimal environment on melting ice and snow. These organisms are also able to shape their environment, through a feedback cycle that involves the albedo. In fact, since these organisms are darker than snow and ice, their presence increases the light absorption and promotes the melting of underlying snow or ice 2-4 . On the surface of glaciers, such extremophiles often aggregate with inorganic material (i.e. mineral dust) to form cryoconite 5,6 . Cryoconite is a dark sediment 5,7 that increases the absorption of visible radiation 4,8 , and promotes the formation of characteristic cryoconite holes 9 which are globally recognized as an hot spot of biodiversity on ice 10 . Besides living organisms, cryoconite is known to concentrate pollutants such as contaminants and radionuclides 11,12 . This may represent a problem in the future, with a possible secondary release of these substances to the environment 13,14 .Cryoconite accumulated in cryoconite holes has a limited impact on glacier and ice sheet surface mass balance. Instead, the presen...

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“…On the Greenland Ice Sheet, algal cell abundance, which ranged from 90 cells · mL −1 to 0.98 × 10 4 cells · mL −1 , increased significantly with the amount of visible impurities seen on the ice surface (Holland et al. ). Correlations between average algal cell counts and DON and DOC surface ice concentrations were significant.…”

Section: Diversity and Community Structurementioning

confidence: 99%

Snow and Glacial Algae: A Review¹

Hoham

Remias

2020

Journal of Phycology

124

118

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Snow or glacial algae are found on all continents, and most species are in the Chlamydomonadales (Chlorophyta) and Zygnematales (Streptophyta). Other algal groups include euglenoids, cryptomonads, chrysophytes, dinoflagellates, and cyanobacteria. They may live under extreme conditions of temperatures near 0°C, high irradiance levels in open exposures, low irradiance levels under tree canopies or deep in snow, acidic pH, low conductivity, and desiccation after snow melt. These primary producers may color snow green, golden‐brown, red, pink, orange, or purple‐grey, and they are part of communities that include other eukaryotes, bacteria, archaea, viruses, and fungi. They are an important component of the global biosphere and carbon and water cycles. Life cycles in the Chlamydomonas–Chloromonas–Chlainomonas complex include migration of flagellates in liquid water and formation of resistant cysts, many of which were identified previously as other algae. Species differentiation has been updated through the use of metagenomics, lipidomics, high‐throughput sequencing (HTS), multi‐gene analysis, and ITS. Secondary metabolites (astaxanthin in snow algae and purpurogallin in glacial algae) protect chloroplasts and nuclei from damaging PAR and UV, and ice binding proteins (IBPs) and polyunsaturated fatty acids (PUFAs) reduce cell damage in subfreezing temperatures. Molecular phylogenies reveal that snow algae in the Chlamydomonas–Chloromonas complex have invaded the snow habitat at least twice, and some species are polyphyletic. Snow and glacial algae reduce albedo, accelerate the melt of snowpacks and glaciers, and are used to monitor climate change. Selected strains of these algae have potential for producing food or fuel products.

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

Cited by 40 publications

References 62 publications

Over Winter Microbial Processes in a Svalbard Snow Pack: An Experimental Approach

Over Winter Microbial Processes in a Svalbard Snow Pack: An Experimental Approach

Glacier algae foster ice-albedo feedback in the European Alps

Snow and Glacial Algae: A Review¹

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

Cited by 40 publications

References 62 publications

Over Winter Microbial Processes in a Svalbard Snow Pack: An Experimental Approach

Over Winter Microbial Processes in a Svalbard Snow Pack: An Experimental Approach

Glacier algae foster ice-albedo feedback in the European Alps

Snow and Glacial Algae: A Review1

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Snow and Glacial Algae: A Review¹