This work package focuses on the seasonal dynamics of pelagic primary production, phytoplankton community structure and carbon cycling during an annual cycle. While these seasonal dynamics are known at the entrance of the fjord, they remain understudied during much of the year within and outside the fjord. The seasonal influence of terrestrial and glacial freshwater, nutrient dynamics and light conditions on phytoplankton community and production will be studied in 3-4 key areas along a land/glacier-fjord-ocean transect. Focus will be on identifying the relative influence of physical (nutrient limitation, stratification, vertical mixing) and biological (zooplankton grazing) drivers on primary production and carbon cycling. Work will include ship based measurements of primary production and nutrient addition studies

This study will collaborate closely with the water chemistry work package on nutrients, pigments and C/N concentrations, as well with the zooplankton work package on grazing impact. The present work package will also take active part in collection of hydrographical parameters (CTD).

In addition, this work package will also measure and compartmentalize the seasonal sinking flux of particulate material at the key area using short-term drifting sediment traps. Experimental work on the sinking material collected may include biomass specific production, thus evaluating the seasonal condition of sinking phytoplankton.

Site: Sanna cruise, Godthåbsfjorden, Nuuk, Greenland

PI: Thomas Juul-Pedersen