Horizon 1 1 17 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES Limnology and Oceanography Letters [16 p.] OCEAN INDIEN 2023 fdi:010090207 ENG Limnology and Oceanography Letters ISI:001060102900001 10.1002/lol2.10343 https://www.documentation.ird.fr/hor/fdi:010090207 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/2023-10/010090207.pdf [Early access] Horizon (IRD) Dinitrogen (N-2) 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 N-2 fixation and diazotroph DNA data in the IO. Our analysis reveals basin-scale yearly rates between similar to 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. 034 ; 084 UR235 / UR182 Inde