Long term decline of the planktonic biomass in a hotspot of nitrogen fixation.

ABSTRACT: Oceanic N₂ fixation by diazotrophic microorganisms is the primary external source of new nitrogen to the surface ocean sustaining net production of organic matter. Studying long-term trends in biomass within N₂ fixation hotspots is crucial for understanding and predicting the response of N₂ fixation to global climate change. Here we developed a bio-optical model based on the spectral phytoplankton absorption coefficient derived from satellite ocean color observations to estimate a proxy for particulate organic nitrogen in the western tropical South Pacific. We demonstrate the existence of a seasonal new biomass production annually over the past 20 years, likely driven by recurrent N₂ fixation. Importantly, our results also reveal a gradual declin

SUBMITTER: Fumenia A 

PROVIDER: S-EPMC12753634 | biostudies-literature | 2025 Nov

REPOSITORIES: biostudies-literature