Berthelot H. auteur aut IRD Benavides M. auteur aut IRD Moisander P. H. auteur aut IRD Grosso O. auteur aut IRD Bonnet Sophie auteur aut IRD text journalArticle eng text/pdf born digital access Dinitrogen (N-2) fixation rates were investigated in the euphotic layer of the Bismarck and Solomon Seas using N-15(2) incubation assays taking into account both the particulate and the dissolved pools. Average depth-integrated particulate N-2 fixation rates were 203 (range 43-399) and 1396 (range 176-3132)mol N m(-2) d(-1) in the Bismarck and Solomon Seas, respectively. In both seas, N-2 fixation measured in the dissolved pool was similar to particulate N-2 fixation, highlighting the potentially substantial underestimation of N-2 fixation in oceanic budgets when only particulate N-2 fixation is considered. Among the diazotroph phylotypes targeted using quantitative polymerase chain reaction amplification of nifH genes, Trichodesmium was the most abundant. Regression analyses suggest that it accounted for the major proportion of N-2 fixation. However, unicellular cyanobacterial and non-cyanobacterial diazotrophs were also occasionally abundant. This study reports high pelagic N-2 fixation rates and confirms that the Western Tropical South Pacific is a hot spot for marine N-2 fixation. specialized diazotrophy Trichodesmium Crocosphaera Cyanothece N release PACIFIQUE 032 036 44 16 8414-8423 2017 0094-8276 https://www.documentation.ird.fr/hor/fdi:010071022 10.1002/2017gl073856 0094-8276 [F B010071022] https://www.documentation.ird.fr/hor/fdi:010071022 https://www.documentation.ird.fr/intranet/publi/2017/10/010071022.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2017-10-31 2023-07-11 fdi:010071022 fre