Exopolymer alteration of physical properties of sea ice and implications for ice habitability and biogeochemistry in a warmer Arctic

The physical properties of Arctic sea ice determine its habitability. Whether ice-dwelling organisms can change those properties has rarely been addressed. Following discovery that sea ice contains an abundance of gelatinous extracellular polymeric substances (EPS), we examined the effects of algal...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2011-03, Vol.108 (9), p.3653-3658
Main Authors: Krembs, Christopher, Eicken, Hajo, Deming, Jody W
Format: Article
Language:English
Subjects:
Algae
Alteromonadaceae
Arctic Regions
Bacillariophyceae
Bacteria
Biogeochemistry
Biological Sciences
Biopolymers
Biopolymers - chemistry
Brines
Cell culture
Colwellia
Diatoms - chemistry
Ecosystem
Geological Phenomena
Global warming
Glycoproteins
Ice
Ice Cover - chemistry
Ice Cover - microbiology
Marine
Melosira
Melosira arctica
Porosity
Salinity
Salts
Sea ice
Sea water
Seas
Temperature
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Summary:The physical properties of Arctic sea ice determine its habitability. Whether ice-dwelling organisms can change those properties has rarely been addressed. Following discovery that sea ice contains an abundance of gelatinous extracellular polymeric substances (EPS), we examined the effects of algal EPS on the microstructure and salt retention of ice grown from saline solutions containing EPS from a culture of the sea-ice diatom, Melosira arctica. We also experimented with xanthan gum and with EPS from a culture of the cold-adapted bacterium Colwellia psychrerythraea strain 34H. Quantitative microscopic analyses of the artificial ice containing Melosira EPS revealed convoluted ice-pore morphologies of high fractal dimension, mimicking features found in EPS-rich coastal sea ice, whereas EPS-free (control) ice featured much simpler pore geometries. A heat-sensitive glycoprotein fraction of Melosira EPS accounted for complex pore morphologies. Although all tested forms of EPS increased bulk ice salinity (by 11-59%) above the controls, ice containing native Melosira EPS retained the most salt. EPS effects on ice and pore microstructure improve sea ice habitability, survivability, and potential for increased primary productivity, even as they may alter the persistence and biogeochemical imprint of sea ice on the surface ocean in a warming climate.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.1100701108