Controls on the autochthonous production and respiration of organic matter in cryoconite holes on high Arctic glaciers

Authors Organisations
  • Jon Telling(Author)
    University of Bristol
  • Alexandre Magno Anesio(Author)
    University of Bristol
  • Martyn Tranter(Author)
    University of Bristol
  • Marek Stibal(Author)
    University of Bristol
  • Jon Hawkings(Author)
    University of Bristol
  • Tristram Irvine-Fynn(Author)
  • Andy Hodson(Author)
    University of Sheffield
  • Catriona Butler(Author)
    University of Bristol
  • Marian Yallop(Author)
    University of Bristol
  • Jemma Wadham(Author)
    University of Bristol
Type Article
Original languageEnglish
Article numberG01017
Number of pages10
JournalJournal of Geophysical Research
Volume117
Issue numberG1
Early online date18 Feb 2012
DOI
Publication statusPublished - Mar 2012
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Abstract

There is current debate about whether the balance of photosynthesis and respiration has any impact on the net accumulation of organic matter on glacier surfaces. This study assesses controls on rates of net ecosystem production (NEP), respiration, and photosynthesis in cryoconite holes during the main melt season (June–August 2009) on three valley glaciers in Svalbard. Cryoconite thickness and organic matter content explained 87% of the total variation in rates of respiration (in units of volume), and organic matter (but not sediment depth) was a significant (p< 0.05) control on photosynthesis (by volume). The average rates of respiration and gross photosynthesis within the cryoconite holes were overall closely balanced, ranging from net autotrophic to heterotrophic. Sediment depth explained over half the variation of NEP, with net autotrophic rates typical only in sediment <3 mm thick. The measured rates of NEP were not sufficient to account for the organic matter which has likely accumulated in the cryoconite on timescales of less than decades, suggesting three alternatives for the source of the organic matter. First, the glacier surface may have received windblown allochthonous organic material from surrounding environments. Second, cryoconite may consist of in-washed autochthonous material from the glacier surface which has comparable organic carbon content. Third, much of the organic matter may have accumulated in the hole during a nascent period, when rates of NEP were much higher. The cycling of autochthonous labile carbon produced by phototrophs may sustain a significant proportion of the total in situ microbial activity within cryoconite holes.