Increased Freshwater and Biogenic Fluxes: The Flip-side of Arctic Sea-ice Retreat

We invert the image of retreating Arctic sea-ice, and focus on the expanding area of the Seasonal Ice Zone (SIZ): that region that is ice-covered in winter, but exposed to the atmosphere and full sun in the summer. Before about 2004, this region was mostly restricted to the continental shelves. Recently, however, it has grown to include much of the deep Canada Basin, creating a new biome: the deepwater SIZ. The changing extent and depth of the SIZ has major implications for biological communities: at the surface where sunlight is already boosting productivity in previously oligotrophic areas, and in the benthos, where ecosystems rely on post-bloom detritus for nutrients. We use satellite imagery and satellite-derived sea-ice tracks to show changes in the SIZ and changes in the flux of sea-ice melt to shallow and deep biomes in the Western Arctic. Melting ice stabilizes the water column and redistributes ice-rafted material, including seed populations, detritus and nutrient-rich sediments, all of which contribute to productivity in the expanded SIZ.