Glacial meltwater mediated sediment release affects phytoplankton productivity and biomass in Kongsfjorden (Spitsbergen).

Increased heat content and advection of Atlantic water have elevated the average temperature in fjords on the west coast of Spitsbergen, including Kongsfjorden. This has increased glacial melting, influencing stratification and glacial sediment release, Both stratification and light attenuation strongly govern phytoplankton productivity. Here we asked if glacial meltwater and sediment release affect phytoplankton productivity and chlorophyll a biomass in Kongsfjorden. We showed an earlier and stronger onset of stratification, but a much shallower euphotic depth, near the glacier. As a consequence, productivity was much lower. The middle of the fjord was also affected by these conditions but much later in the season resulting in a higher productivity in the beginning of the season. Thus, we conclude that spatial differences occur due to light attenuation differences. Yet, meltwater effects are similar in central and inner Kongsfjorden due to overall stratification.