About the Editor

DAVID N. THOMAS is Professor of Arctic Ecosystem Research in the Faculty of Biological and Environmental Sciences, University of Helsinki. Previously he spent 24 years in the School of Ocean Sciences, Bangor University, Wales, where he is now an Honorary Professor. He studies marine systems, with a particular emphasis on sea ice and land-coast interactions in the Arctic and Southern Oceans as well as the Baltic Sea. He also edited a related book: Sea Ice, 3rd Edition (2017), which is also published by Wiley-Blackwell.

Preface xiii List of Contributors xv 1 What Is the Arctic? 1Kjell Danell 1.1 Setting the Scene 1 1.2 In Which Ways Is the Arctic Different? 2 1.3 How Was the Arctic Discovered? 3 1.4 How Large Is the Arctic? 4 1.5 What Is in the Arctic? 4 1.5.1 Arctic Haze and Ice Fog 4 1.5.2 Aurora Borealis 5 1.6 Climate and Weather 5 1.7 Ice and Snow 6 1.8 Permafrost, Polygons, Pingos, and Palsas 6 1.9 Animals, Plants, and Fungi 7 1.10 Arctic Ecosystems 9 1.10.1 Terrestrial Ecosystems 10 1.10.2 Freshwater Ecosystems 12 1.10.3 Marine Ecosystems 14 1.10.4 Humans 15 1.11 Which Natural Resources and Ecosystem Services does the Arctic Offer? 17 1.12 Biotic Changes in the Arctic 19 References 22 2 Arctic Ecology - A Paleoenvironmental Perspective 23Michael Pisaric and John P. Smol 2.1 Introduction 23 2.2 The Distant Past 25 2.2.1 Bones, DNA, and Megafauna 26 2.2.2 Beringian Biota 27 2.2.3 Ancient DNA 29 2.3 Rings and Things: Examining Paleoenvironmental and Paleoclimatic Change Using Dendrochronology 30 2.3.1 Dendrochronology in Action: Examples from the Field 32 2.4 Lake Sediments: Continuous Archives of Environmental Change 33 2.5 Paleolimnology and Arctic Climate Change 37 2.5.1 Subfossil Pollen, Stomata, and Macrofossils for Tracking Vegetation Change 38 2.5.2 Charcoal and Past Wildfires 39 2.5.3 Using Past Assemblage Changes in Lake Biota to Reconstruct Past Climatic Trends 39 2.5.4 Using Paleolimnology to Study the Source and Fate of Contaminants 43 2.5.5 Linking Paleolimnology and Archeology: Tracking the Limnological Effects of Early Peoples in the Arctic 48 2.6 Concluding Remarks 49 References 50 3 Climate Change in the Arctic 57Edward Hanna, Joseph E. Nolan, James E. Overland, and Richard J. Hall 3.1 Introduction to Arctic Climates - Datasets Available for Analyzing Climate Change 57 3.2 Atmospheric Aspects of Arctic Climate Change: Arctic Amplification and Global Warming, Changes in Air Temperature and Precipitation, and Changes in Atmospheric Circulation 59 3.3 Oceanic Aspects of Arctic Climate Change, Including Surface and Deep Ocean Circulation Changes 61 3.4 Climate Change Impacts on Arctic Sea Ice and Greenland Ice Sheet - The Unprecedented Recent Decline in Late Summer Sea-Ice Cover and Record Greenland Ice Sheet Surface Melt and Mass Loss 65 3.5 Feedbacks in the Arctic Climate System and Global Impacts - the Ice/Albedo Feedback and Ice Insulation Feedbacks - the "Warm Arctic, Cold Continents" Hypothesis 71 3.6 Concluding Remarks 73 References 75 4 Arctic Permafrost and Ecosystem Functioning 81Torben R. Christensen 4.1 Permafrost and Ecosystems in the Arctic 81 4.2 Permafrost Shapes the Landscape 83 4.2.1 Permafrost Specific Landforms and Their Importance for Ecosystems 83 4.2.2 Permafrost Specific Landforms and Effects of a Changing Climate 86 4.3 The Biology of Permafrost 87 4.3.1 Microbes 87 4.3.2 Vegetation 88 4.4 Ecosystem Function - Carbon Cycling in Permafrost Environments 91 4.4.1 General Carbon Cycling 91 4.4.2 Methane Emissions 92 4.5 Concluding Remarks 94 References 95 5 Arctic Tundra 103John Hobbie, Gaius Shaver, Toke Thomas Høye, and Joseph Bowden 5.1 Distribution and Description of Arctic Tundra 103 5.2 Tundra Organisms: A Typical Food Web 105 5.3 Flora and Fauna: Diversity and Communities 106 5.4 Primary Production and Organic Matter Stocks in the Low and High Arctic 110 5.5 Primary Production and Organic Matter Stocks 112 5.6 Adaptations to the Arctic Tundra 112 5.6.1 Plant Adaptations 112 5.6.2 Microbial Activity and Soil Carbon and Nitrogen 115 5.6.3 Invertebrates: Diversity, Freeze-Tolerance, and Freeze-Avoidance 116 5.6.4 Vertebrates of the Tundra: Wintertime Survival Strategies 117 5.7 Reproductive Strategies 118 5.8 Populations and Communities of the Tundra 120 5.8.1 Diversity and Interactions: The Case of Beringia 120 5.8.2 Development of Arctic Tundra Food Webs: Complexity, Insects 121 5.8.3 Belowground Arctic Food Web: Bacteria, Mycorrhizal Fungi, Nitrogen, and Carbon Cycling 122 5.9 Tundra Ecosystem Analysis 123 5.9.1 Why Nutrient Limitation? 123 5.9.2 Nitrogen Budget: Pools of Nitrogen, Rates of Transport, and Transformations 124 5.9.3 Carbon Budget: Pools, Gross Photosynthesis and Respiration, Accumulation and Feedbacks 126 5.9.4 Insights from Manipulation Experiments: Control of Net Primary Production and Herbivory by Nutrients, Light, and Heat 126 5.10 Expected Future Changes and Responses in Arctic Tundra 128 5.10.1 Effects of Increased Shrubs 128 5.10.2 Pest Outbreaks, Changes in Phenology and Species Interactions 129 References 130 6 Ecology of Arctic Glaciers 133Alexandre M. Anesio and Johanna Laybourn-Parry 6.1 Introduction 133 6.2 The Biodiversity and Food Webs of Glacial Habitats 136 6.2.1 Ice Shelves 136 6.2.2 Supraglacial or Cryolakes 138 6.2.3 Cryoconite Material, Cryoconite Holes, and Wet Ice Surfaces 139 6.2.4 Snow on the Surface of Ice 141 6.2.5 Life Within Ice 141 6.2.6 Life in Subglacial Environments 143 6.3 Quantification of Microbial Processes in Glaciers and Export of Material to Adjacent Ecosystems 144 6.3.1 Supraglacial Habitats: Ice Shelf Lakes, Ponds, Cryoconites 144 6.3.2 Subglacial Habitats 149 6.4 Anthropogenic Impacts 151 References 152 7 Ecology of Arctic Lakes and Ponds 159Erik Jeppesen, Kirsten S. Christoffersen, Milla Rautio, and Torben L. Lauridsen 7.1 Introduction 159 7.2 Physical and Chemical Characteristics of Arctic Lakes and Ponds 160 7.3 Biological Communities and Production 162 7.3.1 Phytoplankton and Phytobenthos 162 7.3.2 Macrophytes 164 7.3.3 Microbial Loop 165 7.3.4 Zooplankton and Zoobenthos 165 7.3.5 Fish 168 7.3.6 Food Webs 169 7.4 Global Climate Change and Arctic Lakes 171 References 174 8 Ecology of Arctic Streams and Rivers 181Alexander D. Huryn 8.1 Introduction 181 8.1.1 What Is an Arctic River? 181 8.2 A Primer on Stream Ecology: General and Arctic Perspectives 183 8.2.1 The Longitudinal Dimension 184 8.2.2 The Vertical Dimension 202 8.2.3 The Lateral Dimension 207 8.3 Concluding Remarks 209 References 211 9 Ecology of Arctic Pelagic Communities 219Malin Daase, Jørgen Berge, Janne E. Søreide, and Stig Falk-Petersen 9.1 Introduction 219 9.2 The Arctic Marine Highways: The Transpolar Drift and the Interconnected Current Systems 220 9.3 Members and Key Players of Arctic Pelagic Communities 224 9.3.1 At the Base - Primary Producers and Microbial Communities 224 9.3.2 In the Middle - Resident Consumers and Life Strategies of Arctic Zooplankton 229 9.3.3 At the Top - Pelagic Predators 239 9.4 A Lipid-Driven Food Chain 241 9.5 Effects of Climate Change 242 9.5.1 Timing 243 9.5.2 Changes in Species Distribution 243 References 246 10 Ecology of Arctic Sea Ice 261C. J. Mundy and Klaus M. Meiners 10.1 Introduction to Sea Ice 261 10.2 Types of Habitats 262 10.3 Food Webs and Carbon Flow 264 10.4 Physical Environment 268 10.5 Colonization of Sea Ice and Winter Survival 270 10.6 Adaptations to and Relationships with Environmental Conditions 272 10.6.1 Temperature and Salinity 272 10.6.2 Space and Permeability 275 10.6.3 Light 276 10.7 Climate Change and the Ice-Associated Ecosystem 278 References 279 11 Ecology of Arctic Shallow Subtidal and Intertidal Benthos 289Paul E. Renaud, Jan Marcin W¿s¿awski, and Kathleen Conlan 11.1 Introduction 289 11.2 The Physical Environment 290 11.2.1 Temperature 290 11.2.2 Light 290 11.2.3 Waves 291 11.2.4 Ice Cover 291 11.2.5 Freshwater Discharge and Salinity 293 11.3 Biomes 294 11.3.1 Origins and Distribution of Sediments 294 11.3.2 Soft-Sediment Communities 295 11.3.3 Hard Substrate 297 11.3.4 Vegetated Substrate 300 11.4 Disturbance Regimes and Succession 302 11.4.1 Ice Scour 302 11.4.2 Strudel Scour 304 11.4.3 Natural Gas Seepage and Petroleum Extraction 305 11.4.4 Large-Mammal Feeding Pits 305 11.4.5 Recolonization of Arctic Benthos 306 11.4.6 Human Impacts 307 11.5 Trophic Interactions 308 11.5.1 Feeding Strategies in Arctic Shallow Benthos 308 11.5.2 Food Sources for Benthic Fauna 309 11.5.3 Benthos as a Food for Top Predators in the Arctic 310 11.5.4 Carbon and Nutrient Cycling 314 11.6 Reproduction in Coastal Benthos 315 11.7 Effects of Global Climate Change on Shallow Arctic Benthos 316 11.7.1 Reduced Ice Cover 319 11.7.2 Documented Effects on Natural Systems in the Intertidal Zone 319 11.7.3 Coastal Erosion 319 References 320 12 Ecology of Arctic Shelf and Deep Ocean Benthos 325Monika K¿dra and Jacqueline M. Grebmeier 12.1 Introduction 325 12.2 The Physical Environment 326 12.2.1 Light 327 12.2.2 Temperature 327 12.2.3 Sea Ice 328 12.2.4 Sediment Characteristics 328 12.3 Biodiversity, Community Structure, and Functioning of Shelf and Deep Sea Benthos 330 12.3.1 Benthic Definitions 330 12.3.2 Brief Overview of Major Taxa in Benthic Communities 331 12.3.3 Biodiversity 335 12.3.4 Functional Diversity 337 12.3.5 Arctic Commercial Benthic Species 338 12.4 Productivity and Food Webs of Shelf and Deep Sea Benthos 339 12.4.1 Primary Production and Food Sources 339 12.4.2 Pelagic-Benthic Coupling 341 12.4.3 Benthic Community Structure and Food Webs 343 12.4.4 Benthic Communities as a Food Source for Benthic-Feeding Upper Trophic Levels 346 12.5 Impact of Global Climate Change on Shelf and Deep Sea Benthic Communities 348 References 349 13 Fat, Furry, Flexible, and Functionally Important: Characteristics of Mammals Living in the Arctic 357Niels M. Schmidt, Olivier Gilg, Jon Aars, and Rolf A. Ims 13.1 Introduction 357 13.2 The Mammal Assemblage in the Arctic Today 358 13.2.1 Terrestrial Mammals 358 13.2.2 Herbivores 358 13.2.3 Predators 359 13.2.4 Marine Mammals 360 13.3 Arctic Mammals and Adaptations to Life in the Arctic 366 13.3.1 Fur, Fat and Extremities 367 13.3.2 Behavioral Adaptations to Life in the Arctic 368 13.4 The Role of Mammals in Arctic Ecosystems 369 13.4.1 Removal of Plant Material by Terrestrial Herbivores 371 13.4.2 Transport of Nutrients and Seeds by Arctic Mammals 372 13.4.3 Mammal Predator-Prey Dynamics 374 13.5 The Future for Arctic Mammals in a Changing Climate 374 13.6 Concluding Remarks...