IMIS

We report here an environmental genomic and small subunit ribosomal RNA (SSU rRNA) analysis of winter and summer Antarctic Peninsula coastal seawater bacterioplankton. Intense inter-seasonal differences were reflected through shifts in community composition and functional capacities encoded in winter and summer environmental genomes with significantly higher phylogenetic and functional diversity in winter. In general, inferred metabolisms of summer bacterioplankton were characterized by chemoheterotrophy, photoheterotrophy and aerobic anoxygenic photosynthesis while the winter community included the capacity for bacterial and archaeal chemolithoautotrophy. Chemolithoautotrophic pathways were dominant in winter and were similar to those recently reported in global‘dark ocean’ mesopelagic waters. If chemolithoautotrophy is widespread in the Southern Ocean in winter, this process may be a previously unaccounted carbon sink and may help account for the unexplained anomalies in surface inorganic nitrogen content.
Geographic coverage: Samples were collected in the nearshore region of Anvers Island, near Palmer Station.
Taxonomic coverage: Plankton surveys of community structure were conducted of those organisms passing through a 1.6 micron glass fiber filter.
Sampling methods: Seawater was collected by submersible pump and filtered at the Station, see Grzymski et al. 2012 for details. Sanger sequence data was automatically assembled and chimera checked; metagenome sequence data was automatically annotated at the Joint Genome Institute (see Grzymski et al. 2012).