The melting of the cryosphere is among the most conspicuous consequences of climate change, and a significant source of freshwater to the Southern Ocean (SO). As a crucial sink for atmospheric carbon dioxide (CO2), anticipated physical changes in the Southern Ocean will bring modifications to its biogeochemical processes and role in the Earth climate. Predicted increases in iron and nutrient influx to the SO surface waters are likely to impact its primary production and contribution to biological carbon export. However, there remains uncertainty about the significance and magnitude of these projections on primary producers, with likely consequences on the rest of the marine ecosystem. CRYOMICS aims to characterise and quantify the fate of cryospheric exported bioavailable nutrients, trace metals and carbon on phytoplankton utilisation pathways with broader implication on the functioning of the biological carbon pump in the KHS. We hypothesise that biogeochemical enrichment from melting ice shelves leads to a direct positive response of the phytoplankton and sea ice algae community, enhancing its productivity and metabolic functions while favouring larger-celled species such as diatoms. Focusing primarily on the understudied Kong Håkon VII Sea (KHS) in the Eastern Weddell Gyre, along a unique cryosphere-ocean continuum, CRYOMICS combines intensive sampling, biogeochemical analyses and metagenomics to systematically understand the structure and function of microbiomes in marine ecosystems associated with the cryosphere and amidst contemporary changes. Through the support of the MSCA, this project will provide a coordinated and comprehensive dataset of this region of the Southern Ocean, shedding light on microbial interactions and their potential vulnerabilities to perturbations, a dimension currently lacking in climate models. This invaluable insight will enhance our understanding of future projections for the Southern Ocean, including its impact on Antarctic Sea ice.

Marine chemical pollution poses known threats to human health and to biodiversity, ecosystem and societal services. The Arctic is a major sink of global mercury (Hg) pollution. Arctic sediments, sea and glacial ice constitute vast Hg reservoirs. Recent studies raise concerns about their increasing role as local Hg sources. In a rapidly warming Arctic, the consequences of potentially increased environmental Hg on marine biota remain unknown. The objective of SEASOL is to identify the pathway(s) of Hg bioaccumulation in marine food webs of the High Arctic Kongsfjorden (Svalbard). This changing glacial fjord is recognised as a ‘natural laboratory’ of climate change in the Arctic. The fellow’s earlier research has shown the sole measurement of Hg levels as insufficient to connect biotic Hg dynamics to environmental change, whereas the analysis of Hg stable isotopes proved to be a promising tool for source discrimination and biotic transfer. SEASOL will build on the novel application of stable isotope analysis to identify the sources of Hg within the fjord system and the pathways to Hg accumulation within sentinel marine species. On the short-term, the study will provide fundamental knowledge to help understand how emerging sources of Hg from rapid environmental change will impact Arctic marine predators. On the long-term, SEASOL will contribute to the development of early-warning, adaptive management strategies, including modelling, for mitigating the cumulative impact of pollutants and climate change on Arctic marine species. This multidisciplinary approach and the central position of the host institution (Norwegian Polar Institute) in the field of Polar Research will equip the Fellow with a broad set of new skills and lay the foundation for building her specific niche as a future leader in marine pollution science.