Microbial formation of labile organic carbon in Antarctic glacial environments

Smith, Heidi J.; Foster, Rachel A.; McKnight, Diane M.; Lisle, John T.; Littmann, Sten; Kuypers, Marcel M. M.; Foreman, Christine M.

doi:10.1038/ngeo2925

Cited by 75 publications

(58 citation statements)

References 36 publications

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“…A small subset of samples returned net zero rates of carbon loss. This was attributed to lysis of bacterial cells during filtering, which has recently been highlighted as a concern for bioavailability studies using filters with a 0.2‐μm pore size (Smith et al, ), and thus, these samples were excluded from analysis. Results from this study were compared with published results from similar bioassay experiments.…”

Section: Methodsmentioning

confidence: 99%

Dissolved organic matter variations in coastal plain wetland watersheds: The integrated role of hydrological connectivity, land use, and seasonality

Hosen

Armstrong

Palmer

2018

Hydrological Processes

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Dissolved organic matter (DOM) is integral to fluvial biogeochemical functions, and wetlands are broadly recognized as substantial sources of aromatic DOM to fluvial networks.Yet how land use change alters biogeochemical connectivity of upland wetlands to streams remains unclear. We studied depressional geographically isolated wetlands on the Delmarva Peninsula (USA) that are seasonally connected to downstream perennial waters via temporary channels. Composition and quantity of DOM from 4 forested, 4 agricultural, and 4 restored wetlands were assessed. Twenty perennial streams with watersheds containing wetlands were also sampled for DOM during times when surface connections were present versus absent. Perennial watersheds had varying amounts of forested wetland (0.4-82%) and agricultural (1-89%) cover. DOM was analysed with ultraviolet-visible spectroscopy, fluorescence spectroscopy, dissolved organic carbon (DOC) concentration, and bioassays. Forested wetlands exported more DOM that was more aromatic-rich compared with agricultural and restored wetlands. DOM from the latter two could not be distinguished suggesting limited recovery of restored wetlands;DOM from both was more protein-like than forested wetland DOM. Perennial streams with the highest wetland watershed cover had the highest DOC levels during all seasons; however, in fall and winter when temporary streams connect forested wetlands to perennial channels, perennial DOC concentrations peaked, and composition was linked to forested wetlands. In summer, when temporary stream connections were dry, perennial DOC concentrations were the lowest and protein-like DOM levels the highest. Overall, DOC levels in perennial streams were linked to total wetland land cover, but the timing of peak fluxes of DOM was driven by wetland connectivity to perennial streams.Bioassays showed that DOM linked to wetlands was less available for microbial use than protein-like DOM linked to agricultural land use. Together, this evidence indicates that geographically isolated wetlands have a significant impact on downstream water quality and ecosystem function mediated by temporary stream surface connections.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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Section: Methodsmentioning

confidence: 99%

Dissolved organic matter variations in coastal plain wetland watersheds: The integrated role of hydrological connectivity, land use, and seasonality

Hosen

Armstrong

Palmer

2018

Hydrological Processes

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“…Regardless of the mechanism, Smith et al 2 and Musilova et al 3 have established that microbial carbon cycling on glacier surfaces cannot be ignored. Microbial activity contributes labile dissolved organic matter to supraglacial and downstream environments where it is combined with organic matter from within or below the glacier.…”

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confidence: 99%

“…approach the question of microbial carbon cycling somewhat differently; they explore microbial communities in small, water-filled holes in the supraglacial system of the Greenland Ice Sheet. Using complementary methods to Smith et al 2 ., they observed overall net organic carbon production, resulting from higher rates of production via photosynthesis than consumption via respiration in all supraglacial habitats during one melt season (May to August). The finding of a net supraglacial carbon surplus in Greenland is thus consistent with the conclusion Smith et al 2 .…”

mentioning

confidence: 99%

“…Using complementary methods to Smith et al 2 ., they observed overall net organic carbon production, resulting from higher rates of production via photosynthesis than consumption via respiration in all supraglacial habitats during one melt season (May to August). The finding of a net supraglacial carbon surplus in Greenland is thus consistent with the conclusion Smith et al 2 . draw based on their observations in Antarctica.…”

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confidence: 99%

“…Smith et al 2 address the balance of microbially-mediated carbon fluxes in a supraglacial stream system in Antarctica with an elegant combination of incubation experiments, carbon isotope analyses, and spectroscopy. First, they used spectroscopy to confirm that dissolved organic matter in Antarctic streams was likely derived from microbes.…”

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confidence: 99%

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The power of glacial microbes

Kujawinski

2017

Nature Geosci

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Organic carbon fluxes from glaciers are a key control on biogeochemical cycles in polar regions. Two analyses of carbon cycling in glaciers show the importance of glacier-surface microbial communities in setting these inputs. Elizabeth B. KujawinskiGlaciers were once considered inhospitable environments for life. However, over the past 15-20 years, vibrant and diverse microbial communities have been documented in all areas of the ice 1 . These communities are generally found in association with liquid water, either between the base of the glacier and the bedrock, or in pores that range in scale from micrometre-scale structures within the ice lattice to larger holes and streams atop the ice itself. However, the balance between the amount of fixed carbon produced by these microbes and that consumed has remained unclear. Writing in Nature Geoscience, Smith et al 2 . and Musilova et al 3 . show that the microbial communities fix more carbon than expected and thus play important roles in the glacial carbon cycle in Antarctica and the Greenland Ice Sheet, respectively.

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Glaciers and Land‐to‐Ocean Flux of Carbon

Paulsen¹,

Robson²

2019

Encyclopedia of Water

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Glaciers, ice caps, and ice sheets currently cover 12% of the Earth's land surface. The vast majority of glaciers worldwide are now in a state of retreat at unprecedented rates, with the most substantial mass loss originating from Greenland (37% of the global). The mass of ice‐locked organic matter is substantial and represents a hitherto poorly understood reservoir of organic carbon. In this article, we aim to summarize the current data on the concentrations of organic carbon across glacial systems and its origin and fate. Further, we aim to discuss the land‐to‐ocean flux of organic carbon and the effect on downstream environments. Several studies have suggested the glacial dissolved organic carbon (DOC) to have a pronounced impact on the coastal ecosystems because glacial DOC is highly bioavailable, i.e. has a high potential to feed downstream heterotrophic organisms. These studies, however, do not consider that the bioavailable carbon of coastal systems is in fact higher than in the glacial runoff. Contrary to previous studies, we, therefore, stress that glaciers are not a major source of neither DOC or bioavailable DOC and instead identify new focus areas in the field, such as the influence of the catchment area and the role of particulate organic carbon.

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Microbial formation of labile organic carbon in Antarctic glacial environments

Cited by 75 publications

References 36 publications

Dissolved organic matter variations in coastal plain wetland watersheds: The integrated role of hydrological connectivity, land use, and seasonality

Dissolved organic matter variations in coastal plain wetland watersheds: The integrated role of hydrological connectivity, land use, and seasonality

The power of glacial microbes

Glaciers and Land‐to‐Ocean Flux of Carbon

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