Cyanobacteria and cyanophage contributions to carbon and nitrogen cycling in an oligotrophic oxygen-deficient zone

• DOI: 10.1038/s41396-019-0452-6
• Publication Date: 2019-06-27T16:03:41Z
• Authors: Clara A Fuchsman; Hilary I Palevsky; Brittany Widner; Megan Duffy; Michael C G Carlson; Jacquelyn A Neibauer; Margaret R Mulhol...; Richard G Keil; Allan H Devol; Gabrielle Rocap
• Keywords: Carbon fibers; Cycling; Nitrogen Cycle

Up to half of marine N losses occur in oxygen-deficient zones (ODZs). Organic matter flux from productive surface waters is considered a primary control on N2 production. Here we investigate the offshore Eastern Tropical North Pacific (ETNP) where secondary chlorophyll maximum resides within ODZ. Rates production and carbon export mixed layer productivity were consistent with oligotrophic waters. However, sediment trap nitrogen fluxes increased between 105 150 m, indicating organic Metagenomic metaproteomic characterization indicated that was attributable cyanobacterium Prochlorococcus, numerous photosynthesis fixation proteins detected. The presence chemoautotrophic ammonia-oxidizing archaea nitrite oxidizer Nitrospina detection nitrate oxidoreductase cyanobacterial oxygen Cyanobacteria cyanophage also present large (>30 μm) particles material. Particle cyanophage-to-host ratio exceeded 50, suggesting viruses help convert cyanobacteria into sinking matter. Nitrate reduction anammox detected, congruent previously reported We suggest autochthonous ODZ contributes ETNP.