Sulphate reduction rates of arctic deep sea sediments measured at station MSM16/2_809-1 (REF, Reference)

Turnover rates were determined for surface sediment cores obtained in 2009 and 2010. Sulfate reduction (SR) were measured ex situ by the whole core injection method (doi:10.1080/01490457809377722). We incubated the samples at in situ temperature (1.0°C) for 12 hours with carrier-free 35**SO4 (dissolved in water, 50 kBq). Sediment was fixed in 20 ml 20% ZnAc solution for AOM or SR, respectively. Turnover rates were measured as previously described (doi:10.4319/lom.2004.2.171).

Sulphate reduction rates of Håkon Mosby mud volcano sediments measured at station MSM16/2_823-1 (Z3-S3, old flow surface)

Turnover rates were determined for surface sediment cores obtained in 2009 and 2010. Sulfate reduction (SR) were measured ex situ by the whole core injection method (doi:10.1080/01490457809377722). We incubated the samples at in situ temperature (1.0°C) for 12 hours with carrier-free 35**SO4 (dissolved in water, 50 kBq). Sediment was fixed in 20 ml 20% ZnAc solution for AOM or SR, respectively. Turnover rates were measured as previously described (doi:10.4319/lom.2004.2.171).

Metadata und statistic analysis of archael and bacterial sequences originating from sediments of the Håkon Mosby mud volcano (Z1-Z3, all habitats)

DNA extraction was carried out as described on the MICROBIS project pages (http://icomm.mbl.edu/microbis ) using a commercially available extraction kit. We amplified the hypervariable regions V4-V6 of archaeal and bacterial 16S rRNA genes using PCR and several sets of forward and reverse primers (http://vamps.mbl.edu/resources/primers.php). Massively parallel tag sequencing of the PCR products was carried out on a 454 Life Sciences GS FLX sequencer at Marine Biological Laboratory, Woods Hole, MA, following the same experimental conditions for all samples. Sequence reads were submitted to a rigorous quality control procedure based on mothur v30 (doi:10.1128/AEM.01541-09) including denoising of the flow grams using an algorithm based on PyroNoise (doi:10.1038/nmeth.1361), removal of PCR errors and a chimera check using uchime (doi:10.1093/bioinformatics/btr381). The reads were taxonomically assigned according to the SILVA taxonomy (SSURef v119, 07-2014; doi:10.1093/nar/gks1219) implemented in mothur and clustered at 98% ribosomal RNA gene V4-V6 sequence identity. V4-V6 amplicon sequence abundance tables were standardized to account for unequal sampling effort using 1000 (Archaea) and 2300 (Bacteria) randomly chosen sequences without replacement using mothur and then used to calculate inverse Simpson diversity indices and Chao1 richness (doi:10.2307/4615964). Bray-Curtis dissimilarities (doi:10.2307/1942268) between all samples were calculated and used for 2-dimensional non metric multidimensional scaling (NMDS) ordinations with 20 random starts (doi:10.1007/BF02289694). Stress values below 0.2 indicated that the multidimensional dataset was well represented by the 2D ordination. NMDS ordinations were compared and tested using Procrustes correlation analysis (doi:10.1007/BF02291478). All analyses were carried out with the R statistical environment and the packages vegan (available at: http://cran.r-project.org/package=vegan), labdsv (available at: http://cran.r-project.org/package=labdsv), as well as with custom R scripts. Operational taxonomic units at 98% sequence identity (OTU0.03) that occurred only once in the whole dataset were termed absolute single sequence OTUs (SSOabs; doi:10.1038/ismej.2011.132). OTU0.03 sequences that occurred only once in at least one sample, but may occur more often in other samples were termed relative single sequence OTUs (SSOrel). SSOrel are particularly interesting for community ecology, since they comprise rare organisms that might become abundant when conditions change.16S rRNA amplicons and metagenomic reads have been stored in the sequence read archive under SRA project accession number SRP042162.

Sulphate reduction and methane oxidation rates of Håkon Mosby mud volcano sediments measured at station MSM16/2_855-1 (Z2-S3, aged flow surface)

Sulfate reduction (SR) and anaerobic oxidation of methane (AOM) were measured ex situ by the whole core injection method (doi:10.1080/01490457809377722). We incubated the samples at in situ temperature (1.0°C) for 12 hours with either 14** CH4 (dissolved in water, 2.5 kBq) or carrier-free 35** SO4 (dissolved in water, 50 kBq). Sediment was fixed in 25 ml 2.5% sodium hydroxide (NaOH) solution or 20 ml 20% ZnAc solution for AOM or SR, respectively. Turnover rates were measured as previously described (http://edoc.mpg.de/177065; doi:10.4319/lom.2004.2.171).

Sulphate reduction and methane oxidation rates of Håkon Mosby mud volcano sediments measured at station MSM16/2_847-1 (Z2-S2, aged flow surface)

Sulfate reduction (SR) and anaerobic oxidation of methane (AOM) were measured ex situ by the whole core injection method (doi:10.1080/01490457809377722). We incubated the samples at in situ temperature (1.0°C) for 12 hours with either 14** CH4 (dissolved in water, 2.5 kBq) or carrier-free 35** SO4 (dissolved in water, 50 kBq). Sediment was fixed in 25 ml 2.5% sodium hydroxide (NaOH) solution or 20 ml 20% ZnAc solution for AOM or SR, respectively. Turnover rates were measured as previously described (http://edoc.mpg.de/177065; doi:10.4319/lom.2004.2.171).