Cryptic oxygen cycling in anoxic marine zones.

ABSTRACT: Oxygen availability drives changes in microbial diversity and biogeochemical cycling between the aerobic surface layer and the anaerobic core in nitrite-rich anoxic marine zones (AMZs), which constitute huge oxygen-depleted regions in the tropical oceans. The current paradigm is that primary production and nitrification within the oxic surface layer fuel anaerobic processes in the anoxic core of AMZs, where 30-50% of global marine nitrogen loss takes place. Here we demonstrate that oxygenic photosynthesis in the secondary chlorophyll maximum (SCM) releases significant amounts of O₂ to the otherwise anoxic environment. The SCM, commonly found within AMZs, was dominated by the picocyanobacteria Prochlorococcus spp. Free O₂ levels in this layer were, however, unde

SUBMITTER: Garcia-Robledo E 

PROVIDER: S-EPMC5547588 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature