The Ecology of Snow and Ice Environments

199 Pages·2012·5.6 MB·English

by  Johanna Laybourn-Parry, Martyn Tranter, and Andrew J. Hodson

The Ecology of Snow and Ice Environments
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The Ecology of
Snow and Ice
Environments
Johanna Laybourn-Parry
Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, UK
Martyn Tranter
Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, UK
and
Andrew J. Hodson
Department of Geography, University of Sheffi eld, UK
1
1

Great Clarendon Street, Oxford ox2 6dp
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Preface
‘As far as we could see, the inland ice was an unbroken regarded as another ecosystem in the cryosphere. It
plateau with no natural landmarks. From the hinterland, has become evident that biological processes play
in a vast solid stream, the ice fl owed with heavily cre- an important role in the geochemistry of these envi-
vassed downfalls near the coast’. ronments. Like other extreme environments, such
Douglas Mawson The Home as Antarctic lakes, they are systems dominated by
of the Blizzard (1915) microorganisms. Today, glaciology demands an
interdisciplinary approach involving microbiol-
‘Unseen and untrodden under their spotless mantle of ice
ogists, geochemists, glaciologists, and modellers.
the rigid polar regions slept the profound sleep of death
Now it is not uncommon to fi nd university research
from the earliest dawn of time. Wrapped in his white
groups involving all of these disciplines working
shroud, the mighty giant stretched his clammy ice-limbs
together in an integrated manner. The Bristol
abroad, and dreamed his age-long dreams’.
Glaciology Centre exemplifi es this approach. The
Fridtjof Nansen Farthest North (1898)
literature is expanding exponentially, but one of the
I ce and snow environments in the polar and alpine major challenges is to elucidate in much more detail
regions have always been a focus of fascination for what the microbial communities of the cryosphere
humankind. There is something almost seductive contribute to biogeochemical processes, particularly
about the stark beauty of icy places. They demanded in subglacial environments.
exploration, and as the history books show extraor- W hile there are many excellent books dealing
dinary people like Nansen, Amundsen, Scott, with specifi c components of cryosphere biology,
Mawson, and Shackleton sought to reveal their there is no single volume that covers a wide range of
secrets, in some cases at enormous human cost. The ice and snow environments. This volume is intended
age of exploration paved the way for the large-scale for both the specialist and non-specialist. Many stu-
scientifi c investigations of today, supported by the dents of glaciology have little biological knowledge,
type of logistics and technology that the early and likewise biologists may lack knowledge of the
explorers could never have imagined. The polar physical and chemical aspects of the cryosphere.
regions are warming more rapidly than lower lati- The important issue of climate change is embedded
tudes and this has heightened interest in their ice within each chapter, rather than being treated sepa-
sheets, glaciers, sea ice, and ice-covered lakes. rately under one heading. We have covered a wide
Climate change and its possible impact on ecosys- spectrum of cryospheric environments (excluding
tem function and biodiversity have become major the permafrost) including snow, supra- and subgla-
scientifi c issues. cial and ice sheet environments, sea ice, and lake ice.
I ce sheets and glaciers have not traditionally been The fi rst chapter is intended as a background intro-
the domain of biologists, rather they have been the duction to the more detailed treatment of each envi-
territory of physical and chemical glaciological ronment in the succeeding chapters. We have also
investigations. It has only been in the last decade or included a chapter on astrobiology because many of
so that glacial environments have come to be the ice environments are regarded as an analogue
vi PREFACE
for extraterrestrial life. Lastly, we consider future black and white illustrations. M. Tranter a cknowledges
directions, as some exciting technologies are being a Leverhulme Fellowship (R/4/RFG/2010/06000)
developed that provide much greater scope for during which this book was produced.
studying life in glacial environments on Earth and
Johanna Laybourn-Parry, Bristol Glaciology
on other planets.
Centre, University of Bristol
W e would like to thank our editors Ian Sherman
Martyn Tranter, Bristol Glaciology Centre,
and Helen Eaton at the Oxford University Press and
University of Bristol
the other staff involved in the production of this book.
We are indebted to colleagues worldwide who have Andrew Hodson, Department of Geography,
generously provided photographic illustrations and University of Sheffi eld
Paul Coles at Sheffi eld University for producing the May 2011
Contents
Abbreviations ix
1. An introduction to ice environments and their biology 1
1.1 Introduction 1
1.2 Introduction to functional dynamics and the organisms 2
1.2.1 Community structure and function 2
1.2.2 Organisms 6
1.3 The cryosphere: past and present 8
1.3.1 The last glacial maximum 8
1.3.2 Contemporary fl uctuations of glaciers and ice sheets 8
1.3.3 Snowball Earth 9
1.4 Sea ice 12
1.4.1 Nature of sea ice 12
1.4.2 Sea ice communities 14
1.5 Lake ice 16
1.6 Glaciers 19
1.6.1 Ice mass balance zones in glacial ecosystems 19
1.6.2 Hydrological zonation in surface ecosystems 21
1.6.3 Supraglacial lakes 23
1.6.4 Water distribution in subsurface ecosystems 24
1.6.5 Water in subglacial habitats 25
1.6.6 Overview: broad structure and characteristics of glacial ecosystems 27
1.6.7 Life on glaciers 30
1.7 Snow 31
1.7.1 Physical and chemical characteristics 31
1.7.2 Biological activity in snow 35
2. Snow 37
2.1 Snow as an environment 37
2.2 Life on and in snow 37
2.2.1 Snow algae 37
2.2.2 Bacteria in snow 39
2.3 Impact of snow on environments it covers seasonally 41
2.3.1 Activity under the snow 41
2.3.2 Impact of the release of accumulated nutrients in the snow pack at spring melt 44
2.3.3 Variations in snow depth 46
viii CONTENTS
3. Ice surface environments 47
3.1 Ice shelves 47
3.1.1 Introduction 47
3.1.2 Biology of ice shelf lakes 48
3.2 Glaciers and ice sheets 52
3.2.1 Supraglacial habitats 52
3.2.2 Spatial variations in the biota in supraglacial habitats 56
3.2.3 Cryoconite 57
3.2.4 Carbon cycling and biological production 64
3.2.5 Other debris habitats, including the ice margin 71
4. Sea and lake ice 73
4.1 Sea ice 73
4.1.1 Introduction 73
4.1.2 Adaptations 77
4.1.3 Community structure and production 78
4.2 Lake ice 92
4.2.1 Introduction 92
4.2.2 Community structure and production 95
5. Subglacial environments 101
5.1 Introduction 101
5.2 Biology of subglacial environments 104
5.2.1 Wet-based glaciers 105
5.2.2 Blood Falls 107
5.3 Life in glacial ice 110
5.4 Subglacial lakes 111
5.5 Lake Vida 117
6. Astrobiology 121
6.1 Introduction 121
6.2 Extraterrestrial cryospheric environments 122
6.2.1 Mars 122
6.2.2 Europa: a Jovian moon 125
6.2.3 Enceladus: a small Saturnian moon 126
6.2.4 Titan: a large Saturnian moon 127
6.3 Weaknesses of terrestrial analogues for extraterrestrial cryospheric environments 128
7. Future directions 129
7.1 Introduction 129
7.2 Priority fi eld sites for future research 130
7.3 Remote sensing development 133
7.4 Sensor technology 135
7.5 Modelling 139
7.6 Molecular biology 140
7.7 Elucidating the evolution of extremophile communities 141
Glossary 143
References 149
Index 173
Abbreviations
AARs accumulation area ratios
AMP adenosine monophosphate
APR adenosine 5´ phosphosulphate reductase
APS adenosine 5´ phosphosulphate
ARA acetylene reduction activity
BGE bacterial growth effi ciency
BIAs blue ice areas
BP bacterial production
BR bacterial respiration
CF concentration factor
x
CFUs colony forming units
CO carbon dioxide
2
cps capsular polysaccharides
DAPI 4´,6-diamidino-2-phenylindole
DGGE denatured gradient gel electrophoresis
DIC dissolved inorganic carbon
DMS dimethyl sulphide
DMSP dimethysulfonioproprionate
DNA deoxyribonucleic acid
DOC dissolved organic carbon
DOM dissolved organic matter
DON dissolved organic nitrogen
E shade adaptation indices
k
EPs exopolymer particles
eps extracellular polysaccharides
EPS extracellular polymer substances
FISH fl uorescence in situ hybridization
FLBs fl uorescently labelled bacteria
GISP Greenland Ice Sheet Project
GPR ground penetrating radar
HGT horizontal gene transfer
HNAN heterotrophic nanofl agellates
HPLC high performance liquid chromatography
IPCC Intergovernmental Panel on Climate
LC-MS/MS liquid chromatography mass spectrometry
LGM Last Glacial Maximum
LIA Little Ice Age