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Title: Supraglacial systems biology of dynamic Arctic microbial ecosystems
Author: Gokul, Jarishma
ISNI:       0000 0004 7425 9541
Awarding Body: Aberystwyth University
Current Institution: Aberystwyth University
Date of Award: 2017
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Arctic glacier surfaces are a biologically active region of the cryosphere, supporting several cosmopolitan microbial taxa. Bacterial communities across the different ice surfaces are spatially variable and significantly influenced by biogeography and biogeochemistry. In summer, the supraglacial surface reveals extensive cryoconite hole coverage that is correlated to surface albedo, melt rate, mass balance and biological activity. However, the relative importance of temporal changes on bacterial community composition and activity in these supraglacial niches have yet to be determined. To enhance this knowledge, community dynamics of bacteria in cryoconite, snow and meltwater streams were investigated synthetically and on Foxfonna ice cap, Foxfonna valley glacier and the Greenland Ice Sheet. By means of microscopy, metabolomics and high throughput sequencing of 16S rRNA genes and cDNA from 16S rRNA, the summer bacterial community was evaluated to determine the relative importance of taxa on supraglacial surfaces. This aided in unravelling the complex interactions that are prevalent in a simple microbial niche exposed to unique environmental conditions, nutritional deficits and geological constraints. Overall, the bacteria on Foxfonna and Greenland supraglacial surfaces display distinct seasonal transient behaviour. Taxa appear selective to their physical environment and biogeochemical state in the cryosphere, characterized by integral associations with the photoautotrophic Cyanobacteria, Phormidesmis priestleyi, that mediates formation of a robust microhabitat conglomerated with humics, extracellular polymeric substances and minerals that are essential to the diverse and productive cryoconite community. The rare biosphere provides a source for heterotrophic bacterial recruitment in cryoconite, snow and stream habitats, the latter of which exhibit high abundances of proteobacterial subclasses only minimally dissimilar from cryoconite during the boreal summer. Network analysis predicts that these taxa may be responsible for the observed seasonal shifts of activity in favourable conditions, while generating the essential nutrient reserves required during winter dormancy periods.
Supervisor: Edwards, Arwyn ; Mur, Luis ; Irvine-Fynn, Tristram Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available