Original Article

Subject Category: Microbial ecosystem impacts

The ISME Journal (2012) 6, 2302–2313; doi:10.1038/ismej.2012.107; published online 27 September 2012

Photophysiology and albedo-changing potential of the ice algal community on the surface of the Greenland ice sheet

Marian L Yallop1, Alexandre M Anesio2, Rupert G Perkins3, Joseph Cook4, Jon Telling2, Daniel Fagan1, James MacFarlane5, Marek Stibal6, Gary Barker1, Chris Bellas2, Andy Hodson4, Martyn Tranter2, Jemma Wadham2 and Nicholas W Roberts1

  1. 1School of Biological Sciences, University of Bristol, Bristol, UK
  2. 2Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, Bristol, UK
  3. 3School of Earth and Ocean Sciences, Cardiff University, Cardiff, UK
  4. 4Department of Geography, University of Sheffield, Sheffield, UK
  5. 5Interface Analysis Centre, University of Bristol, St Michael’s Hill, UK
  6. 6Department of Geochemistry, Geological Survey of Denmark and Greenland, Copenhagen K, Denmark

Correspondence: ML Yallop, School of Biological Sciences, University of Bristol, Woodland Road, BS8 1UG, UK. E-mail: Marian.Yallop@bristol.ac.uk; AM Anesio, Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, Bristol, BS8 1SS, UK. E-mail: a.m.anesio@bristol.ac.uk

Received 24 April 2012; Revised 1 August 2012; Accepted 1 August 2012
Advance online publication 27 September 2012

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Abstract

Darkening of parts of the Greenland ice sheet surface during the summer months leads to reduced albedo and increased melting. Here we show that heavily pigmented, actively photosynthesising microalgae and cyanobacteria are present on the bare ice. We demonstrate the widespread abundance of green algae in the Zygnematophyceae on the ice sheet surface in Southwest Greenland. Photophysiological measurements (variable chlorophyll fluorescence) indicate that the ice algae likely use screening mechanisms to downregulate photosynthesis when exposed to high intensities of visible and ultraviolet radiation, rather than non-photochemical quenching or cell movement. Using imaging microspectrophotometry, we demonstrate that intact cells and filaments absorb light with characteristic spectral profiles across ultraviolet and visible wavelengths, whereas inorganic dust particles typical for these areas display little absorption. Our results indicate that the phototrophic community growing directly on the bare ice, through their photophysiology, most likely have an important role in changing albedo, and subsequently may impact melt rates on the ice sheet.

Keywords:

ice algae; photophysiology; albedo; Greenland ice sheet