Data S1 Materials and methods.

Fig. S1 X-ray diffraction patterns of sediment collected from the middle of the lake (a) and near the lake edge (b). K = kaolinite, Al = alunite, S = smectite. Unmarked peaks have not been identified.

Fig. S2 ROV GPS position from 8-16-09, showing correlation between onboard GPS (Lowrance LMS-480M) and shore-based sub-meter SX Blue II GPS (Geneq). Shore-based positions available only when ROV was close to handheld receiver at N/W shore.

Fig. S3 Top: sonar soundings during 8-16-09 transect, showing strong echoes from steeply sloped sides (yellow), with weak echoes from gas bubbles (white arrows) or soft mud or sediment deposits, with hints of deep vents (red arrows). Bottom: gray trace shows raw sonar data, including upwelling gas bubble reflections. Red trace shows manual corrections for soft mud bottom.

Fig. S4 Contour maps of water temperatures at surface (left) and 1 m depth (right). Hot spots at 1 m were shallow near-shore sediments.

Fig. S5 Time-lapse images from 9-8-09, showing convection from several gas vents. Lake water has been contrast-enhanced to reveal suspended sediment. Red arrows show vent locations.

Table S1 Genes and PCR primers used to screen CO2 fixation pathways.

Table S2 Genes and PCR primers used to screen N cycle pathways.

Table S3 Highest signal intensity hybridizations. The top 25 detected genes are shown in descending order; numbers rounded to nearest 0.1.

gbi12041-sup-0002-videoS1a.movvideo/mov8138KVideo S1 a. BSL 8-3-10, b. 8-4-10: 15-s unedited images taken above lake, merged in Windows Movie Maker, with time stamp added. Site D is in foreground, site A at top.
gbi12041-sup-0003-videoS2a.movvideo/mov8568KVideo S2 a. BSL 8-3-10, b. 8-4-10 contrast enhanced: images were batch-processed in Photoshop (Adobe Inc.) using the Magic Wand tool to select the lake water, and apply automatic contrast enhancement to help visualize water convection. This produces artifacts around the lake's perimeter and shoreline.

Please note: Wiley Blackwell is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.