High-resolution net and gross biological production during a Celtic Sea spring bloom

Isabel Seguro, Alina D. Marca, Suzanne J. Painting, Jamie D. Shutler, David J Suggett, Jan Kaiser

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Shelf seas represent only 10% of the ocean area, but support up to 30% of all oceanic primary production. There are few measurements of shelf-sea biological production at high spatial and temporal resolution in such heterogeneous and physically dynamic systems. Here, we use dissolved oxygen-to-argon (O2/Ar) ratios and oxygen triple isotopes (16O, 17O, 18O) to estimate net and gross biological production in the Celtic Sea during spring 2015. O2/Ar ratios were measured continuously using a shipboard membrane inlet mass spectrometer (MIMS). Additional discrete water samples from CTD hydrocasts were used to measure O2/Ar depth profiles and the δ(17O) and δ(18O) values of dissolved O2. These high-resolution data were combined with wind-speed based gas exchange parameterisations to calculate biologically driven air-sea oxygen fluxes. After correction for disequilibrium terms and diapycnal diffusion, these fluxes yielded estimates of net community (N(O2/Ar)) and gross O2 production (G(17O)). N(O2/Ar) was spatially heterogeneous and showed predominantly autotrophic conditions, with an average of (33±41) mmol m-2 d-1. G(17O) showed high variability between 0 and 424 mmol m-2 d-1. The ratio of N(O2/Ar) to G(17O), ƒ(O2), was (0.18±0.03) corresponding to 0.34±0.06 in carbon equivalents. We also observed rapid temporal changes in N(O2/Ar), e.g. an increase of 80 mmol m-2 d-1 in less than 6 hours during the spring bloom, highlighting the importance of high-resolution biological production measurements. Such measurements will help reconcile the differences between satellite and in situ productivity observations, and improve our understanding of the biological carbon pump.
Original languageEnglish
Article number101885
JournalProgress in Oceanography
Early online date6 Dec 2017
Publication statusPublished - Oct 2019


  • Net community production
  • gross production
  • O2/Ar ratio
  • oxygen triple isotopes
  • shelf seas
  • spring bloom
  • Shelf seas
  • Spring bloom
  • Gross production
  • O /Ar ratio
  • Oxygen triple isotopes

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