Replication data for: Subglacial upwelling in spring increases under-ice primary production

The dataset was taken in April 2019 in Billefjorden, Svalbard, a sea-ice covered tidewater glacier influenced fjord. The aim of the study is to investigate the effect of potential subglacial upwelling on oceanographic and biogeochemical processes in the fjord. We hypothesized that subglacial upwelling is present under sea ice, but at lower rates than in summer. However, due to the sea ice blocking any other freshwater inputs and wind mixing, we propose that this upwelling is still important in shaping the sea ice, stabilizing a stratified surface layer, and bringing potentially limiting nutrients to the surface. we measured salinity and temperature profiles in the water column and sea ice together with nutrient concentrations and chlorophyll. We studied the algal and bacterial communities using microscopic and DNA sequencing methods, and measured vertical chlorophyll fluxes and primary and bacterial production to discuss the effects of subglacial upwelling on the carbon cycle.