From ice to ocean: Understanding the impacts of melting glaciers on marine biogeochemical cycles in the Canadian Arctic Archipelago

When glaciers melt, they contribute significant quantities of water and ice, sediments and dissolved chemicals to the ocean. Recent efforts in Greenland and Antarctica show that both the delivery of materials to the marine environment, as well as local changes to ocean circulation induced by the input of freshwater, have the potential to profoundly impact key processes such as primary and secondary production, and by extension the biological carbon pump. Yet, extensive knowledge gaps remain about the chemical composition of glacial meltwater runoff at the ice-ocean interface, the spatial extent of its influence within coastal environs, and the mechanisms by which glaciers affect surface marine microbial communities. Nowhere are these knowledge gaps more prominent than in the Canadian Arctic Archipelago (CAA) – a region where the role of glacial meltwater in marine biogeochemical cycles is almost fully unexplored – despite the fact that it is a hotspot for glacial retreat and meltwater runoff to the ocean. Here, we conduct a regional comparative study of the nearshore coastal zone of glaciated and non-glaciated fjords and of multiple glaciers of varying type (land-terminating, tidewater) and size draining large ice caps. Our study site in Jones Sound, NU is home to the Inuit hamlet of Grise Fiord. Traditional knowledge from this community indicates that the termini of tidewater glaciers in this region are rich in wildlife, providing habitual hunting grounds for its citizens. Guided by this information, we combined shipboard measurements of temperature, salinity, turbidity, and chlorophyll a with bottle samples characterizing oxygen, sediment, carbon, nutrient, metal, and biological community composition to elucidate how these properties evolve with distance from the shore. Results from this study substantially further our understanding of glacier-ocean impacts in the CAA and beyond, while also providing data critical to accurate future projections of high-latitude marine ecosystem productivity and function in this era of climate change.