Evidence of limited N2 fixation in the Southern Ocean
Biological nitrogen fixation is an important source of new nitrogen, influencing ocean fertility and carbon uptake. While recently documented in Arctic waters, its role in the Southern Ocean remains uncertain. We measured nitrogen fixation along the Western Antarctic Peninsula and at Palmer Station over two austral summer months. Rates from 15N2 assay were below conservative detection limits but detectable under less stringent detection thresholds. Continuous acetylene reduction assay provided further support. nifH gene sequencing identified Gammaproteobacteria as the dominating identified diazotrophs, while Epsilonproteobacteria contributed disproportionally to nifH expression when putative nitrogen fixation was highest. Combined with environmental observations, we hypothesize that vertical water mixing resuspended sediments into the water column and contributed to the limited nitrogen fixation. Given the sporadic and low rates, further research is needed to determine whether nitrogen fixation plays a minor role or represents an overlooked process with biogeochemical significance in the Southern Ocean. Low levels of nitrogen fixation may be occurring in the Southern Ocean, according to in-situ measurements of seawater from the western Antarctic Peninsula and Palmer Station
Authors
- Weiyi Tang (ORCID: https://orcid.org/0000-0002-5334-3993)
- Hugh W. Ducklow (ORCID: https://orcid.org/0000-0001-9480-2183)
- Yajuan Lin (ORCID: https://orcid.org/0000-0002-9057-9321)
- Nicolas Cassar (ORCID: https://orcid.org/0000-0003-0100-3783)
- Hugo Berthelot (ORCID: https://orcid.org/0000-0003-1028-5938)
- Julie Robidart (ORCID: https://orcid.org/0000-0001-9805-3570)
- A. Murat Eren (ORCID: https://orcid.org/0000-0001-9013-4827)
- Shuai Gu (ORCID: https://orcid.org/0000-0001-5152-9754)
Institutions
- Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung (DE)
- Centre National de la Recherche Scientifique (FR)
- Carl von Ossietzky Universität Oldenburg (DE)
- Lamont-Doherty Earth Observatory (US)
- Ifremer (FR)
- Université de Bretagne Occidentale (FR)
- Duke University (US)
- National Oceanography Centre (GB)
- Princeton University (US)
- Helmholtz Institute for Functional Marine Biodiversity (DE)
- Max Planck Institute for Marine Microbiology (DE)
- Institut Universitaire Européen de la Mer (FR)
- Laboratoire des Sciences de l'Environnement Marin (FR)
- Institut de Recherche pour le Développement (FR)
- University of South Florida St. Petersburg (US)
- Columbia University (US)
- College of Marin (US)
- Texas A&M University – Corpus Christi (US)
Publication Details
- Journal
- Communications Earth & Environment
- Published
- 2025-04-05
- DOI
- https://doi.org/10.1038/s43247-025-02225-0
- Citations
- 2
- Primary Topic
- Methane Hydrates and Related Phenomena
- Type
- article
- Field-Weighted Citation Impact
- 1.72
Funders
- National Science Foundation