Assessing the Response of Marine Macro- and Micronutrient Bioavailability and Cycling to Arctic Sea-Ice Loss

Sea-ice loss, freshening and stratification changes in the recent past have affected, and are projected to continue to affect, the timing, distribution and biomass production of Arctic primary producers.

Current enhancements observed in primary production are attributed to increased light penetration associated with sea-ice thinning and loss.

However, these enhancements may be a relatively short-term phenomenon that will recede unless there is additional supply of nutrients to the photic zone.

In addition to external inputs through rivers, atmospheric deposition and vertical mixing, internal cycling and redistribution related to sea-ice formation, transport and melting are important mechanisms affecting nutrient distributions in the Arctic Ocean.

Quantifying the individual contributions of these processes to nutrient bioavailability and cycling is imperative in light of ongoing sea-ice retreat but currently hindered by the lack of studies applying source- and process-sensitive tracers.

Therefore, I propose to develop a multi-tracer approach based on a suite of innovative isotopic tracers sensitive to nutrient sources and cycling to be determined in snow, sea ice and seawater obtained from the year-round MOSAiC initiative and from multiple summer cruises to the Arctic Ocean.

By combining established and new analytical techniques in trace element and isotope geochemistry and by conducting laboratory-controlled sea-ice growth experiments, this innovative and interdisciplinary approach will take advantage of cutting-edge knowledge in tracer development and behavior without compromising on the benefit of a seasonally and spatially constraint dataset.

The results will provide a deep understanding of the effects on - and feedbacks within – Arctic marine ecosystems arising from sea-ice loss, reduce uncertainties associated with bioengineering-inspired carbon sequestration efforts and complement Europe’s 2020 strategy to tackle Food Security and Climate Action objectives.