Arctic Sea Ice Ecology

Table of Contents

1. Frontmatter

2. Chapter 1. The Book, and Ecology of Sea Ice

   Lars Chresten Lund-Hansen, Dorte Haubjerg Søgaard, Brian Keith Sorrell, Rolf Gradinger, Klaus Martin Meiners

   Abstract

   This chapter describes the structure of the book and the diverse significance and importance of sea ice. The first section explains how and why the book is structured following the seasonal events governing the abiotic and biotic parameters in sea ice (1.1). The second section places sea ice into a physical and geopolitical perspective with the new and developing international borders in the Arctic Ocean (1.2). Sea ice ecosystems are then compared to other ecosystems (1.3), followed by a section describing the important and global ecological features of sea ice (1.4).

3. Chapter 2. Autumn, Development and Consolidation of Sea Ice

   Lars Chresten Lund-Hansen, Dorte Haubjerg Søgaard, Brian Keith Sorrell, Rolf Gradinger, Klaus Martin Meiners

   Abstract

   This chapter describes the period of development of new ice during autumn freeze-up, different ice types, and development of the brine channels (2.1). Optical properties of young and developing sea ice are described in terms of the transition from open water to bare sea ice, that later can be covered by snow (2.2). The incorporation and scavenging of ice algae, bacteria and meiofauna from the water column during ice growth and freeze-up are then described (2.3). Development of platelet ice, a prominent under-ice feature in Antarctica and recently observed in the Arctic, is described (2.4). The final section describes frost flowers and brine skim development, and the dynamics of the bacteria communities in the frost flowers and brine skim on top of newly formed sea ice (2.5).

4. Chapter 3. Winter, Cold and Mature Sea Ice

   Lars Chresten Lund-Hansen, Dorte Haubjerg Søgaard, Brian Keith Sorrell, Rolf Gradinger, Klaus Martin Meiners

   Abstract

   This chapter describes a period of low air temperatures, darkness or very little light, cold ice, minimum brine volumes, and strongly reduced ice permeability. The first section provides an overview of the physical and optical conditions of this winter ice (3.1). Both snowfall and snowdrift are frequent during winter and an overview of the effects of a thick snow cover on sea ice is provided (3.2). Increased colonization of the sea ice bottom by bacteria and ice algae is initiated in late winter around first light, and an example is given (3.3). Once these microorganisms have colonized the ice the important growth limitations of bacteria and algae are considered (3.4), along with how they are able to adapt to these extreme conditions, and their seasonal species succession (3.5). The purposes of EPS and the functioning of different pigments found in ice algae are described (3.6). This is combined with a description of low light conditions and related photosynthesis (3.7), and exemplified with a case study from Station North, NE Greenland (3.8).

5. Chapter 4. Spring, Summer and Melting Sea Ice

   Lars Chresten Lund-Hansen, Dorte Haubjerg Søgaard, Brian Keith Sorrell, Rolf Gradinger, Klaus Martin Meiners

   Abstract

   This chapter describes one of the most dynamic and ecological important seasons. The onset of ice melt initiates significant changes in the physical properties of the ice (4.1), and the related biotic processes in the spring/summer sea ice are addressed (4.2). Ice algal spring blooms are described and exemplified with two studies from contrasting Arctic sites (4.3). A Case Study 2 has a focus on effects and consequences for ice algae of increased irradiances at the ice bottom in terms of pigments, fatty acids, and MAAs (4.4). Ice algae bloom dynamics are investigated in a combined model and field study (4.5). Melt ponds termed “windows to the ocean” develop on the surface of the ice with increased light transmittance (4.6). Seeding of the ice or water column below with viable ice algae can initiate ice algae or pelagic blooms, and mechanisms are explored in model and field studies (4.7). Case study 3 show that species of meiofauna graze directly on the ice algae, and that the meiofauna establishes an important ecological component in the sea ice (4.8).

6. Chapter 5. Sea Ice in a Climate Change Context

   Lars Chresten Lund-Hansen, Dorte Haubjerg Søgaard, Brian Keith Sorrell, Rolf Gradinger, Klaus Martin Meiners

   Abstract

   This chapter is a description of the role and importance of sea ice and sea ice biota on large scales and in relation to the effects of climate change. The decrease in summer sea ice extent and thickness are evident and described in (5.1). A Case Study 4 based on our observations in the Fram Strait and the Arctic Ocean illustrates some of the consequences and effects of increased inflow of warm Atlantic water (5.2). The question whether more light in an ice-free water column will increase pelagic primary production in the Arctic Ocean, is addressed with a model (5.3). Sea ice plays an important role in the exchange of CO₂ between ocean and atmosphere and the sea ice CO₂ pump is described in (5.4).

7. Chapter 6. Methods and Techniques in Sea Ice Ecology

   Lars Chresten Lund-Hansen, Dorte Haubjerg Søgaard, Brian Keith Sorrell, Rolf Gradinger, Klaus Martin Meiners

   Abstract

   This chapter is a description of the field and laboratory methods that are generally applied in sea ice ecological research. The first section describes sampling techniques and handling of sea ice samples (6.1). Calculations of brine and gas volumes are dealt with in (6.2), and how to measure and calculate optical parameters (6.3). Sampling, handling, and calculation of ice bacterial production are described (6.4), and methods for ice algae biomass spatial distributions are dealt with in (6.5). Measuring photosynthesis and ice algae primary production are described (6.6), and the determination of Chl a content is explained (6.7). The recently developed fluorescence imaging of ice algae distributions and derived photosynthetic parameters are described (6.8). This is followed by a description of the IP₂₅, a substance synthesized by ice algae and applied for mapping sea ice and food web studies (6.9).

8. Backmatter