Sampling:
Water samples collected during the cruise aboard the research vessel icebreaker (RV/IB) Nathaniel B. Palmer, as part of the TRacing the fate of Algal Carbon Export in the Ross Sea (TRACERS) program included nutrients (nitrate, nitrite, silica, phosphate, DOC, DIC, dC13, ). Samples for biological measurements were collected using a rosette sampler fitted with 20 12 L Niskin bottles (General Oceanics), a conductivity, temperature, and depth (CTD) sensor (Sea-Bird Electronics), an SBE 43 dissolved oxygen sensor, and a fluorometer (WET Labs). All seawater samples were stored immediately within 1 h of collection using HDPE amber bottles and all biological material was treated with 0.1% sodium azide (NaN3) solution and stored at 4ºC until analysis.
Metagenome samples:
Two liters of seawater were taken directly from Niskin bottles and filtered onto 47 mm diameter 0.22 µm size pore polycarbonate filters (Millipore) and flash frozen in liquid nitrogen for storage until later analysis. DNA was extracted using the DNeasy Plant Mini Kit from QIAGEN. Illumina adapters and primers for sequencing on PCR products were used (TruSeq). 100 bp, PE reads were generated on the Illumina HiSeq 2500 platform.
Metatranscriptome samples:
Two liters of seawater were taken directly from Niskin bottles and filtered onto 47 mm diameter 0.22 µm size pore polycarbonate filters (Millipore) and flash frozen in liquid nitrogen for storage until later analysis. Illumina ScripSeq kit was used for library prep and ribosomal depletion was done with Epidemiology kit.
Sorted cells metagenome samples:
Size and fluorescene sorted cells (2,000) were resuspended in PBS. Genome amplification was conducted with RepliG kit. Library preparation was conducted with TruSeq kit.