Response of Antarctic cryoconite microbial communities to light.
Microbial communities on polar glacier surfaces are found dispersed on the ice surface, or concentrated in cryoconite holes and cryolakes, which are accumulations of debris covered by a layer of ice for some or all of the year. The ice lid limits the penetration of photosynthetically available radiation (PAR) to the sediment layer, since the ice attenuates up to 99% of incoming radiation. This suite of field and laboratory experiments demonstrates that PAR is an important control on primary production in cryoconite and cryolake ecosystems. Increased light intensity increased efficiency of primary production in controlled laboratory incubations of debris from the surface of Joyce Glacier, McMurdo Dry Valleys, Antarctica. However, when light intensity was increased to levels near that received on the ice surface, without the protection of an ice lid, efficiency decreased and measurements of photophysiology showed that the communities suffered light stress. The communities are therefore well adapted to low light levels. Comparison with Arctic cryoconite communities, which are typically not covered by an ice lid for the majority of the ablation season, showed that these organisms were also stressed by high light, so they must employ strategies to protect against photodamage.
School of Earth and Ocean Sciences, Cardiff University, Cardiff CF10 3AT, UK bagshawe@cardiff.ac.uk.
Elizabeth A
EA
Bagshaw
Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, BS8 1SS, UK.
Jemma L
JL
Wadham
Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, BS8 1SS, UK.
Martyn
M
Tranter
School of Earth and Ocean Sciences, Cardiff University, Cardiff CF10 3AT, UK.
Rupert
R
Perkins
School of Earth and Ocean Sciences, Cardiff University, Cardiff CF10 3AT, UK.
Alistair
A
Morgan
School of Earth and Ocean Sciences, Cardiff University, Cardiff CF10 3AT, UK Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, BS8 1SS, UK.
Christopher J
CJ
Williamson
Departments of Geology and Geography, Portland State University, Portland, Oregon OR 97201, USA.
Andrew G
AG
Fountain
Department of Geography, University of Otago, Dunedin, PO Box 56, New Zealand.
Sean
S
Fitzsimons
Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, TG6 2E3, Canada.
Ashley
A
Dubnick
D000064:Acclimatization; D000864:Antarctic Regions; D001110:Arctic Regions; D017753:Ecosystem; D004734:Energy Metabolism / Q000502:physiology*; D005618:Fresh Water / Q000382:microbiology*; D046448:Ice Cover / Q000382:microbiology*; D008027:Light; D010788:Photosynthesis / Q000502:physiology
PAR; cryoconite; glaciers; photophysiology