Evidence of high N2 fixation rates in the temperate northeast Atlantic ...

• Main Authors: Fonseca-Batista, Debany, Li, Xuefeng, Riou, Virginie, Michotey, Valérie, Deman, Florian, Fripiat, François, Guasco, Sophie, Brion, Natacha, Lemaitre, Nolwenn, Tonnard, Manon, Gallinari, Morgane, Planquette, Hélène, Planchon, Frédéric, Sarthou, Géraldine, Elskens, Marc, LaRoche, Julie, Chou, Lei, Dehairs, Frank
• Format: Text
• Language: English
• Published: ETH Zurich 2019
• Subjects: Northeast Atlantic
• Online Access: https://dx.doi.org/10.3929/ethz-b-000332762; http://hdl.handle.net/20.500.11850/332762

Diazotrophic activity and primary production (PP) were investigated along two transects (Belgica BG2014/14 and GEOVIDE cruises) off the western Iberian Margin and the Bay of Biscay in May 2014. Substantial N2 fixation activity was observed at 8 of the 10 stations sampled, ranging overall from 81 to 384 µmol N m−2 d−1 (0.7 to 8.2 nmol N L−1 d−1), with two sites close to the Iberian Margin situated between 38.8 and 40.7∘ N yielding rates reaching up to 1355 and 1533 µmol N m−2 d−1. Primary production was relatively lower along the Iberian Margin, with rates ranging from 33 to 59 mmol C m−2 d−1, while it increased towards the northwest away from the peninsula, reaching as high as 135 mmol C m−2 d−1. In agreement with the area-averaged Chl a satellite data contemporaneous with our study period, our results revealed that post-bloom conditions prevailed at most sites, while at the northwesternmost station the bloom was still ongoing. When converted to carbon uptake using Redfield stoichiometry, N2 fixation could ... : Biogeosciences, 16 (5) ...