Chemotaxis Side Chamber

Brine sample exposed to a right-to-left serine gradient. Data file 2015.03.30 06-14. Data for Fig. 9 A in paper

Brine at +4 C

Malene Bay brine kept overnight at +4 C with the addition of 1/2 strength 2216 marine medium. File 2015.03.30 05-28. Data for Figures 8F in paper and Video 8

Brine at -4C

Malene Bay brine kept overnight at -4 C with no additions. File 2015.03.28 08-11. Data for Figure 8D in paper and Video 6

Chemotaxis Middle Chamber

Holograms of Malene Bay brine sample exposed to a bottom-to-top serine gradient (data file 2015.03.30 06-28) Data for Fig. 9 B, C in paper and Video S9

FourierMaskNuukData

Fourier mask for data sets

Malene Bay eukaryotes

Malene Bay, unmodified, showing eukaryotes. Data for Fig. 6. Data file 2015.03.25 10-1

Schematic and images of the compact, twin-beam digital holographic microscope.

<p>(A) Schematic showing four main elements (discussed in the text): the source, the sample (specimen path is labeled <i>Spec</i>. and reference path is labeled <i>Ref</i>.), the microscope, and the sensor. (B) Solid model of the hardware. The fiber-fed source assembly is at the bottom, and the imaging camera is at the top. The microscope optics, comprised of the two aspheric lenses and the relay lens, are contained within the 300 mm long lens tube. In the laboratory, a three-axis stage between the source the microscope optics provides easy manual manipulation of the specimen under study. (C) Photograph of the field instrument (top case removed). The optical train, electronics, and computer are contained within a waterproof box. (D) Photo of instrument fully enclosed, as used in the field. The arrow indicates where a sample chamber is inserted; the structure pictured is a placeholder only.</p

FourierMaskNuukData

Fourier mask for data sets

Seawater at +4C

Malene Bay seawater kept overnight at +4 C with the addition of 1/2 strength 2216 marine medium. File 2015.03.30 05-58. Data for Figures 7 and 8E in paper and Videos 4 and 7

Schematic of selected microbial habitats in the frozen environments of sea ice and permafrost.

<p>(A) Sea ice (not drawn to scale). Microorganisms, in particular heterotrophic bacteria, inhabit all dimensions and seasons of sea ice and its snow cover, including thin first-year ice, ice structures on new ice called frost flowers, thick winter and spring ice, and surface melt ponds, despite exposure to high levels of potentially damaging radiation at the ice surface in summer. Most sea-ice bacteria derive from freezing seawater and inhabit the brine network within the ice, but bacteria delivered by atmospheric deposition are detected in overlying snow and surface melt ponds. Sea ice algae, especially diatoms, bloom in spring and summer in the brine channels of bottom ice, where they are bathed with seawater nutrients and receive sufficient sunlight; they have also been found in large aggregates at the bottom of melt ponds and as filamentous mats on the underside of the ice. The porous ice matrix and frost flowers are filled with extracellular polymeric substances (EPS), which are also involved in attachment of under-ice algal mats. (See [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0147700#pone.0147700.ref011" target="_blank">11</a>] [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0147700#pone.0147700.ref018" target="_blank">18</a>], and [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0147700#pone.0147700.ref019" target="_blank">19</a>] for more detail). (B) Permafrost (not drawn to scale). In permanently frozen soil (grey), below the seasonally active layer (dark brown), bacteria and archaea can be found in abundance in cryopegs (buried lenses of relict seawater brines), where EPS concentrations are also high, and in veins of liquid brine that can exist between mineral grains. Freshwater ice wedges (white) that extend into permafrost also contain intact microorganisms, but at far lower abundances than in cryopegs or permafrost veins (See [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0147700#pone.0147700.ref013" target="_blank">13</a>]and [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0147700#pone.0147700.ref014" target="_blank">14</a>] for more detail).</p