Lu Y. Y. auteur aut IRD Wen Z. Z. auteur aut IRD Shi D. L. auteur aut IRD Lin W. F. auteur aut IRD Bonnet Sophie auteur aut IRD Dai M. H. auteur aut IRD Kao S. J. auteur aut IRD text journalArticle eng text/pdf born digital access The N-2 fixation and primary production rates were measured simultaneously using N-15(2) and C-13 incubation assays in the northern South China Sea influenced by the Kuroshio intrusion (KI) seasonally. The degree of KI (KI index, range from 0 to 1) was assessed by applying an isopycnal mixing model. The water column integrated N-2 fixation and primary production for stations with KI index larger than 0.5 were 463 +/- 260 mu mol N center dot m(-2)center dot day(-1) and 62 +/- 19 mmol C center dot m(-2)center dot day(-1), respectively, significantly higher than those for stations with KI index lower than 0.5 (50 +/- 10 mu mol N center dot m(-2)center dot day(-1) and 28 +/- 10 mmol C center dot m(-2)center dot day(-1), respectively). Trichodesmium was the dominant diazotroph at stations with KI index larger than 0.5, with 2 orders of magnitude higher nifH gene abundance than that at stations with KI index lower than 0.5. However, the highest N-2 fixation rates were found in waters with moderate KI index around 0.6, suggesting that frontal zone mixing might stimulate N-2 fixation. Our results demonstrated that diazotrophs (mainly Trichodesmium) were tightly associated with the KI, which modulated the biogeographic distribution of N-2 fixers. In summary, we found the transportation of Trichodesmium by KI, then, we quantified the fraction of KI and N-2 fixation rates in the northern South China Sea. The results suggested that KI generated a new biogeographic regime which could significantly influence the carbon and nitrogen cycles far away from the main stream. specialized MER DE CHINE 032 034 124 10 6983-6996 2019 2169-9275 https://www.documentation.ird.fr/hor/fdi:010077125 10.1029/2018jc014781 2169-9275 [F B010077125] https://www.documentation.ird.fr/hor/fdi:010077125 https://www.documentation.ird.fr/intranet/publi/depot/2020-02-04/010077125.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2019-12-12 2025-02-24 fdi:010077125 fre