Tracing mercury sources in the Arctic marine ecosystem of Kongsfjorden, Svalbard

One of the major challenges limiting the effectiveness of marine pollution prevention is the limited understanding of the sources and exposure pathways of chemicals. The Arctic is a critical hotspot of global change, where the bioavailability and cycling of pollutants in marine food webs are expected to be permanently altered. Insufficient knowledge of changing mercury (Hg) sources and dynamics in the context of a rapidly warming Arctic complicates the assessment of Hg exposure in marine fauna. The novel application of Hg stable isotope analysis (Hg-SIA) holds significant potential to enhance our understanding of the environmental and ecological drivers of Hg sources within ecosystems. This study aims to advance and apply Hg-SIA to identify Hg sources and pathways in a key sentinel bird species, the black-legged kittiwake (Rissa tridactyla), and to assess the potential impact of climate change on Hg pollution. Based on sampling conducted in Kongsfjorden (79°N, 12°E, Svalbard) during spring and summer 2024, we are carrying out comprehensive Hg stable isotope analyses across a broad range of marine ecosystem components, including marine sediments, sea-ice algae, suspended particulate organic matter, zooplankton, benthic invertebrates, various fish species, and blood samples from kittiwakes. Lower trophic-level ecosystem components were collected along a gradient from the Atlantic-influenced mouth of the fjord to the glacially influenced inner fjord, to assess Hg exposure along environmental gradients. While carbon, nitrogen, and sulphur stable isotopes will serve as proxies for the trophic ecology of the kittiwakes, Hg stable isotopes will provide insights into the spatio-temporal sourcing of Hg.