Diazotrophy in the Indian Ocean: Current understanding and future perspectives

Subhadeep Chowdhury, Eric Raes, Cora Hörstmann, Ayaz Ahmed, Céline Ridame, Nicolas Metzl, P. S. Bhavya, Takuya Sato, Takuhei Shiozaki, Sophie Bonnet, Carolin R. Löscher, Arvind Singh, Mar Benavides*


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Dinitrogen (N2) fixation provides the major source of reactive nitrogen in the open ocean, sustaining biological productivity. The Indian Ocean (IO) covers 22% of the ocean surface, while it only represents 1% of the global diazotroph database. Hence, constraining the sources of nitrogen in the IO is crucial. Here, we compile three decades of N2 fixation and diazotroph DNA data in the IO. Our analysis reveals basin-scale yearly rates between ~ 7 and 13 Tg N yr−1. These rates are in the range of previous modeling-based estimates but may represent a lower bound estimate due to the lack of data in this basin. Diazotroph variability among sub-basins may suggest endemicity but needs to be taken with caution due to biased sampling toward certain seasons and uneven spatial coverage. We provide recommendations for a more accurate representation of the IO in the global nitrogen budget and our knowledge of diazotroph biogeography.

TidsskriftLimnology and Oceanography Letters
Udgave nummer5
Sider (fra-til)707-722
StatusUdgivet - okt. 2023

Bibliografisk note

Funding Information:
This work was funded by the project DINDE granted to MB and AS by the Indo‐French Centre for the Promotion of Advanced Research (IFCPAR/CEFIPRA). DINDE is endorsed by the International Indian Ocean Expedition II under project endorsement number IIOE2‐EP41. This work is also funded by project IDEFIX granted by the Pure Ocean Fund to MB. Part of the data compiled were obtained thanks to the OISO program cruise OISO‐30 ( https://doi.org/10.17600/18000679 ) supported by the French institutes INSU (Institut National des Sciences de l'Univers) and IPEV (Institut Polaire Paul‐Emile Victor), OSU Ecce‐Terra (at Sorbonne Université), and the French program SOERE/Great‐Gases. The authors are indebted to Christian Furbo Reeder for his assistance with illustrations. SC was supported by a Campus France scholarship funded by IFCPAR/CEFIPRA.

Publisher Copyright:
© 2023 The Authors. Limnology and Oceanography published by Wiley Periodicals LLC. on behalf of Association for the Sciences of Limnology and Oceanography.


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