net production = 0 (how well is low light used) also quantum

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4 net production = 0 (how well is low light used) also quantum

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6 particulate organic matter = POM particulate organic carbon = POC particulate organic nitrogen = PON zooplankton POM POM fish CO 2 fixation = (photo)autotrophy CO 2 DOM DIC microbial loop bacteria viruses phytoplankton DOM/POM consumption = heterotrophy

7 Micro 20 Nano 2 Pico 0.2 Femto 0.02!m After T. Fenchel Dissolved organic material Virus

8 Micro 20 Nano 2 Pico 0.2 Femto 0.02!m Dissolved organic material Virus After T. Fenchel

9 Micro 20 Nano 2 Pico 0.2 Femto 0.02!m After T. Fenchel Dissolved organic material Virus

10 Log #/ml viruses bacteria phytoplankton zooplankton fish whales Log size

11 CO 2 production Fraction of consumed DOC that is respired as CO 2

12 (Deming, unpublished)

13 (Deming, unpublished)

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16 Sediment-laden sea ice 100 m 10 cm (photos provided by Hajo Eicken)

17 Bacterial abundance a in ice Ice type Sampling location Sample Particlepoor T ( C) ice Snow South Pole x 10 3 Ice sheet Lake ice Sea ice Over Lake Vostok (2 4 km) Greenland (bottom of sheet) Lake Bonney, Antarctica Imikpuk Lake, Alaska Southern Ocean, summer Southern Ocean, winter Arctic Ocean, summer Arctic Ocean, winter 3 9 < 5? to 20 Particle-rich ice x 10 3 > 6 x x x 10 7 x x x x x x x x x x 10 6 Permafrost Northeast Siberia 10 > 1 x 10 8 a Number ml 1 melted ice or g 1 soil for permafrost; data compiled from Carpenter et al. (2000), Delille et al. (1995), Gradinger and Zhang (1997); Grossman and Dieckmann (1994); Helmke and Weyland (1995); Junge et al. (2001, 2003a, 2004), Karl et al. (1999), Priscu and Christner (2004), Rivkina et al. (2000), and Sheridan et al. (2003). (Deming and Eicken, 2007)

18 Sediment-laden sea ice 100 m 10 cm

19 Lake ice vs. sea ice and the role of microstructure Arctic lake ice: k eff 0.01, n l 0.05, α 0.15 Arctic sea ice: k eff 0.28, n l 50, α 0.40 (from Eicken, 2003)

20 Lake ice vs. sea ice: Impurity content and pore microstructure Effective segregation coefficient k eff = S i / S w k eff dependent on impurity concentration, hydrodynamics, growth rate Lake ice: k eff 0.01; Sea ice: k eff 0.12 Si Sw Cs T solid S(z) liquid cons tiona supe laye T(z) z z Tf(z) (from Eicken, 2003)

21 Assur (1960) (also shown in Eicken, 2003) Frozen habitats: Thermal evolution and constraints

22 Frozen habitats: Thermal evolution and constraints V l /V, % a(h 2 O) φ MgCl2 12H2O KCl NaCl 2H2O NaSO4 10H2O H2O(s) Eutectic (V l /V = 0) at about 55 C Temperature, K 270 Seawater, model by Marion & Grant (1997)

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24 Microstructural evolution as a function of temperature: Thin section studies 30 C, p=0.03 A=0.015 mm 2 P A = 0.80 mm -1 Cold ice 2.7 C, p=0.08 A=0.041 mm 2 P A = 1.50 mm C, p=0.11 A=0.108 mm 2 P A = 1.83 mm -1 Warm ice H , Q, 0.08 m depth 20 mm H , Q, 0.12 m depth 30 C, p=0.02 A=0.012 mm 2 P A = 0.58 mm C, p=0.17 A=0.127 mm 2 P A = 3.02 mm C, p=0.21 A=0.199 mm 2 P A = 2.54 mm -1 (see Eicken, 2003)

25 Microstructural evolution as a function of temperature: Magnetic resonance imaging (from Eicken, 2003)

26 Hydrodynamic control of pore microstructure Artificial sea ice, no current Artificial sea ice, 0.16 m/s current a a n mm Major axis, mm Horizontal slice Vertical slice 4 5 b c n mm 2 3 Major axis, mm Horizontal slice Vertical slice 4 5 b c (see Eicken, 2003)

27 Impact of microstructure on transport properties: Permeability Freitag (1999), Eicken (unpubl.) Summer FY/MY ice (SHEBA) "impermeable" "permeable" (from Eicken, 2003)

28 March 2001 Sea ice north of Barrow, Alaska Air temperature of 40 C Junge R/V Sled vertical ice gradient of 20 C (2 m thick) 2 C Deming Eicken

29 Arctic sea-ice core (cm scale) Sea-ice microbial community snow/atmosphere 20 C ~2% brine vol ~20% salt 5 C 2 C ocean 10 cm

30 Typical bacterial content of 0.1 µl of seawater generic bacteria = domains Bacteria + Archaea bacteria ml viruses ml 1 Image obtained by epifluorescence microscopy after staining with a DNA-specific stain (called SYBER Green I). The larger fluorescing objects are the bacteria; arrows point to viruses.

31 Typical sea-ice algae (diatoms) and bacteria (DAPI-stained)

32 Typical chlorophyll profile in clean sea ice (Rysgaard et al., 2001)

33 Depth, m Distribution of ice biota: Dirty Elson Lagoon ice Bacterial abundance: ± 0.7 x 105 cells ml-1 (ice, med. sed. conc.) ± 8.0 x 105 cells ml-1 (ice, high sed. conc.) Particulate conc., mg l Chl a, µg l (Eicken, Junge, Deming, unpublished)

34 Subzero examination of ice thin sections (µm scale) cold room at 5 to 20 C cold room at 5 to 20 C Karen Junge ice core 5 mm 30 mm ice section (see Junge et al., 2001)

35 Thermal evolution and precipitation of salts (see Eicken, 2003)

36 Thermal evolution and precipitation of salts: Mirabilite (T < 8.2 C) (Eicken, 2003)

37 Transmitted light Pore connectivity and fluid transport (transmitted light) 20 C brine pores (photos by Krembs; in Deming, 2007)

38 Transmitted light Transmitted light 20 C brine pores (photos by Krembs; in Deming, 2007)

39 Transmitted light (no stain) Epifluorescent light (DNA stain) bacteria diatoms 15 C (Junge et al., 2001)

40 Diatoms in brine pores Transmitted light with Alcian Blue stain for EPS ice brine pore 15 C stained EPS diatom ice EPS = extracellular polysaccharide substances (exopolymers, gelatinous Cryoprotectant material, or mucous) exopolymers (Krembs et al., 2002)

41 (Krembs et al., submitted)

42 EPS alters the structure of sea-ice pores without EPS with EPS (Krembs & Deming, 2008; Krembs et al., submitted)

43 The habitat is altered in both artificial and natural sea ice 2-D relationship: pore diameter to perimeter (µm) Artificial ice, no EPS Barrow ice, 2001 circumference perimeter (µm) Artificial ice, with EPS Barrow ice, 2002 (Krembs et al., submitted)

44 EPS alteration of ice structure, anchoring of algae a) ice b) c) ice L P D L D C EPS F EPS S S F (Krembs and Deming, 2008)

45 (Krembs et al., submitted)

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48 (pulse amplitude modulated)

49 (Rysgaard et al., 2001)

50 (Rysgaard et al., 2001)

51 (Rysgaard et al., 2001)

52 (Rysgaard et al., 2001)

53 Transmitted light (no stain) Epifluorescent light (DNA stain) bacteria diatoms 15 C (Junge et al., 2001)

54 Triple-point juncture 20 C Brine pore DAPI-stained bacteria (Junge et al., 2001)

55 Particle aggregates Bacteria (Junge et al., 2001)

56 Transmitted light 15 C dividing bacterium 10 µm (Junge et al., 2001)

57 At the coldest temperatures, virtually all active bacteria were associated with surfaces (Junge et al., 2004)

58 Sea-ice bacteria are also embedded in EPS Number of bacteria per EPS particle Equivalent spherical diameter (µm) Equivalent spherical diameter of EPS particle (µm) (Meiners, 2002)

59 CASES Overwintering Leg 5 February 23, 2004

60 CCG Amundsen Noel Green, wildlife observer

61 Ice temperature contours through the winter Ice temperature ( C) Air temp ( C) 18 C 28 C 12 C 22 C 6 C 18 C (Collins et al., 2008)

62 Cells were lost from coldest horizons (Collins et al. 2008)

63 EPS was produced in the coldest horizons (also known to be produced copiously in warm bottom ice) January March March June March -- June (Collins et al. 2008) (Riedel et al. 2006)

64 The colder the ice, the greater the EPS production per cell Fig Wintertime increases in EPS concentration per bacterium in Arctic sea ice as a function of ice temperature in situ. Increases are relative to concentration at the warmest temperature, highlighted by the dotted line at unity. Data are from upper ice depths of cm over a 3-month period from January to March 2004 (Collins et al., 2008), best fit to an exponential curve where r 2 = (Deming, in press)

65 Seasonal progression of bacterial content Fig Idealized depth profiles of seasonal changes in bacterial abundance in sea ice: autumn cell entrainment and enrichment (relative to seawater) into new ice (orange line); winter losses (blue line); spring gains, greatest where algae bloom (green line); and continued summer gains prior to ice melt, with osmotic losses in surface melt ponds and releases from bottom ice during ice melt (from data and concepts in Grossmann & Dieckmann, 1994; Gradinger & Zhang, 1997; Delille et al., 2002; Brinkmeyer et al., 2004; Meiners et al., 2004, 2008; and Collins et al., 2008). (Deming, in press)

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67 (Kaartakallio, 2004)

68 Bacteriophage, viruses that attack bacteria (virus = poison in Latin; phage = to eat)

69 Fig Transmission electron micrograph of the Siphoviridae phage 9A that infects two species of the -Proteobacterial genus Colwellia at subzero temperatures, including the sea ice bacterium C. demingiae (from Wells & Deming, 2006b, with permission). (Deming, in press)

70 Fig. 7.6 (a) Springtime increases in concentrations of chlorophyll a, bacteria and viruses in melted sea ice samples. Data are best fit to linear regressions where r 2 = 0.74, 0.71 and 0.53, respectively. (b) Springtime relationship between ratio of viruses to bacteria (the dotted line highlights the typical ratio of 10 in seawater) and cell-specific bacterial growth (measured by thymidine incorporation). Data are best fit to a logarithmic curve where r 2 = (All data re-plotted from Maranger et al., 1994, with permission). (Deming, in press)

71 Bacterial and viral numbers in sea-ice brine were not static Number VLP of viruses concentration ml 1 brine (ml -1 ) (o) Ice core C 12 C and 16% salt bacteria viruses x---x Bacteria concentration (ml -1 ) (x) Number of bacteria ml 1 brine Viral densities were high, approaching 10 8 ml 1 brine. Contact rates between viruses and bacteria were very high, almost 600 times that in seawater Incubation Time time (h) (h) (Wells and Deming, 2006)

72 Cold-active viral enzymes must have been at work EPS coating (from Hughes et al., 1998)

73 Fig Schematic (not drawn to scale) of a recently opened lead in winter with newly formed sea ice and its surficial frost flowers containing brine (and bacteria and viruses) wicked from the sea ice. Upper left photo shows a field of frost flowers in the Amundsen Gulf of the Canadian Arctic during December 2007 (provided by R.E. Collins); right photo, individual frost flowers (bar = 2 cm) in the same region during the dark month of January 2008 (provided by M. Lin). (Deming, in press)