Differences in First and Multi-Year Sea Ice Melt Signatures and Impacts on the Local Ecosystem during Spring in Fram Strait

The majority of sea ice export from the Arctic Ocean occurs through Fram Strait. In spring, the ice that is pushed south here by surface winds and ocean currents contains both first-year ice from the central Arctic and the Eurasian shelf waters, and multi-year ice which predominantly originates north of Greenland. The different types of sea ice are marked by different thickness (and thereby translucency), brine content, and concentrations of ice algae and dissolved nutrients. Here, we aim to quantify some of these differences and their impact on the local water column and ecosystem. We do so by analyzing ice core samples of both multi-year and first-year ice cores collected during an oceanographic cruise in May 2019. We compare these data to local oceanographic and ecosystem parameters, derived both from in situ measurements (such as CTD casts through the ice and next to it, as well as fluorescence, dissolved oxygen, and surface water pigment and trace metal measurements) and from satellite observations. Our results are a step toward understanding how the melt of different types of sea ice impact the local ecosystem in Fram Strait in general, and spring phytoplankton blooms in particular.