Biological nitrogen fixation in the oxygen-minimum region of the eastern tropical North Pacific ocean.

ABSTRACT: Biological nitrogen fixation (BNF) was investigated above and within the oxygen-depleted waters of the oxygen-minimum zone of the Eastern Tropical North Pacific Ocean. BNF rates were estimated using an isotope tracer method that overcame the uncertainty of the conventional bubble method by directly measuring the tracer enrichment during the incubations. Highest rates of BNF (~4 nM day^-1) occurred in coastal surface waters and lowest detectable rates (~0.2 nM day^-1) were found in the anoxic region of offshore stations. BNF was not detectable in most samples from oxygen-depleted waters. The composition of the N₂-fixing assemblage was investigated by sequencing of nifH genes. The diazotrophic assemblage in surface waters contained mainly Proteobacterial sequen

SUBMITTER: Jayakumar A 

PROVIDER: S-EPMC5607377 | biostudies-literature | 2017 Oct

REPOSITORIES: biostudies-literature