Project Funding: 2016 - 2020

NRA: 2015 NASA: Ocean Biology and Biogeochemistry   

Funded by NASA

Abstract:
The ongoing changes in the circulation of the Subarctic Atlantic are, without question, impacting its marine ecosystems, yet our quantitative understanding of such ecological change(s) remains meager. A fundamental challenge is to predict whether net primary production (NetPP) in this region will increase or decrease under changing northerly and southerly advective flows. Here, we suggest that the balance will depend on regional bottom-up drivers (e.g., stratification, nutrient and light availability, community composition) and top-down drivers (e.g., grazing). A growing understanding of the surface and deep overflows, counterflows, and recirculation patterns within the Subarctic Atlantic is emerging that indicates stronger influences of the Atlantic surface Water (AW) and Arctic-origin Water (ArW) on each other and on the average circulation patterns within the Subarctic Atlantic than previously thought. We define the Subarctic Atlantic as the region encompassed by the Greenland-Iceland-Norwegian (GIN), Irminger and Labrador Seas, where warmer and saltier AWladen with nutrients, plankton and detritus moves north in multiple branches into the Labrador Sea, into the GIN Seas and, eventually, into the Arctic Ocean. Fresher and colder ArWwith sea ice, low nutrients, low plankton and high colored dissolved organic matter moves southwards along the edge of the eastern Greenland and western Labrador Seas and into the N. Atlantic. Here, we will focus on the balance of NetPP in the Subarctic Atlantic as affected by (i) advective losses and gains within this region at large-scales interaction with respect to boundary conditions in the temperate N. Atlantic and Arctic Oceans; (ii) lateral and vertical “export― production within sub-regions of the Subarctic Atlantic at intermediate scales; and (iii) advective and local processes controlling NetPP in the Subarctic Atlantic region. Our questions include the following: o (Q1) What bottom-up (physical and chemical) factors control the NetPP levels in the Subarctic Atlantic, where and when? (Q2) What are the controls of seasonal and sub seasonal variabilities and trends in the SubArctic Atlantic? (Q3) What is the balance between local and advected NetPP in the Subarctic Atlantic during the growth season? o We propose to use a hierarchy of models including a full 3D, coupled, biogeochemical physical model at regional scale (SINMOD) and a specialized 1D satellite ocean color model for phytoplankton NetPP (UQAR-Takuvik), both of which are exceptionally well tuned to high latitudes. Model simulations will be done in concert with mining historical field and satellite data to better understand the temporal evolution of NetPP and its physical and ecological controls over an average annual cycle in the Subarctic Atlantic. o Our results will shed light if the magnitude of NetPP will increase or decrease due to enhanced stratification (warmer AW or fresher ArW conditions, less nutrients) and grazing (immigrating or returning zooplankton). Alternatively, less sea ice in Fram Strait and the Greenland Sea may result in more and earlier open waters and less stratification that may lead to higher NetPP values, as has been predicted north and east of Spitsbergen. A northwards shift in NetPP due to enhanced AW advection is expected. o Our project responds to the ROSES 2015 A.3 OBB (amended) activity 2.3 Research In Support of the Galway Statement: North Atlantic-Arctic Oceanographic Processes by focusing on the exchanges across, and processes within, the Subarctic Atlantic and their effect on NetPP, in a region located north of the NASA-sponsored EXPORTS selected N. Atlantic field site, with a team of Canadian, Danish, Norwegian and US researchers. Our project will openly share all field data assembled as well as promote researcher mobility by including a postdoctoral fellow and a part-time graduate student, both of whom will gain international networking and experience.

Publications:

Mayot, N., Matrai, P., Ellingsen, I. H., Steele, M., Johnson, K., Riser, S. C., Swift, D. 2018. Assessing Phytoplankton Activities in the Seasonal Ice Zone of the Greenland Sea Over an Annual Cycle. Journal of Geophysical Research: Oceans. 123(11), 8004-8025. DOI: 10.1029/2018JC014271

More details may be found in the following project profile(s):

• NASA Ocean Biology & Biogeochemistry (OBB) Project Profile