Diversity and activity of nitrogen‐fixing communities across ocean basins

Recent observations of N 2 fixation rates (NFR) and the presence of nitrogenase ( nifH ) genes from heterotrophic N 2 ‐fixing (diazotrophic) prokaryotes in unusual habitats challenge the paradigm that pelagic marine N 2 fixation is constrained to cyanobacteria in warm, oligotrophic, surface waters. Here, we compare NFR and diazotrophic diversity (assessed via high‐throughput nifH sequencing) from a region known to be dominated by cyanobacterial...