Preprints
https://doi.org/10.5194/egusphere-2022-916
https://doi.org/10.5194/egusphere-2022-916
 
27 Sep 2022
27 Sep 2022

The sensitivity of primary productivity in Disko Bay, a coastal Arctic ecosystem to changes in freshwater discharge and sea ice cover

Eva Friis Møller1, Asbjørn Christensen2, Janus Larsen1, Kenneth David Mankoff3,4, Mads Hvid Ribergaard5, Mikael Kristian Sejr1, Philip Wallhead6, and Marie Maar1 Eva Friis Møller et al.
  • 1Department of Ecoscience, Aarhus University, 4000 Roskilde, Denmark
  • 2DTU Aqua, Technical University of Denmark, DK-2880 Kgs. Lyngby, Denmark
  • 3Department of Glaciology and Climate, Geological Survey of Denmark and Greenland, 1350 Copenhagen, Denmark
  • 4National Snow and Ice Data Center (NSIDC), Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado Boulder, Boulder, CO, 80390, USA
  • 5Danish Meteorological Institute, 2100 Copenhagen, Denmark
  • 6Section for Oceanography, Norwegian Institute for Water Research (NIVA Vest), Bergen, Norway

Abstract. The Greenland Ice Sheet is melting, and the rate of ice loss has increased 6-fold since the 1980s. At the same time, the Arctic sea ice extent is decreasing. Melt water runoff and sea ice reduction both influence light and nutrient availability in the coastal ocean with implications for the timing, distribution and magnitude of phytoplankton production. However, the integrated effect of both glacial and sea ice melt is highly variable in time and space, making it challenging to quantify. In this study, we evaluate the relative importance of these processes for the primary productivity of Disko Bay, West Greenland, one of the most important areas for biodiversity and fisheries around Greenland. We use a high-resolution 3D coupled hydrodynamic-biogeochemical model for 2004 to 2018 validated against in situ observations and remote sensing products. The model estimated net primary production (NPP) varied between 90–147 gC m-2 year-1 during 2004–2018, a period with variable freshwater discharges and sea ice cover. NPP correlated negatively with sea ice cover, and positively with freshwater discharge. Fresh water discharge had a strong local effect within ∼25 km of the source sustaining productive hot spot during summer. When considering the annual NPP at bay scale, sea ice cover was the most important controlling factor. In scenarios with no sea ice in spring, the model predicted ∼30 % increase in annual production compared to a situation with high sea ice cover. Our study indicates that decreasing ice cover and more freshwater discharge can work synergistically and will likely increase primary productivity of the coastal ocean around Greenland.

Eva Friis Møller et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-916', Anonymous Referee #1, 14 Nov 2022
  • RC2: 'Comment on egusphere-2022-916', Anonymous Referee #2, 16 Nov 2022

Eva Friis Møller et al.

Eva Friis Møller et al.

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Short summary
Melt from the Greenland ice sheet and sea ice both influence light and nutrient availability in the Arctic coastal ocean. We use a 3D coupled hydrodynamic-biogeochemical model to evaluate the relative importance of these processes for timing, distribution and magnitude of phytoplankton production in Disko Bay, West Greenland. Our study indicates that decreasing sea ice and more freshwater discharge can work synergistically and increase primary productivity of the coastal ocean around Greenland.