Index‐based approach for estimating vulnerability of Arctic biota to oil spills

Risk of an Arctic oil spill has become a global matter of concern. Climate change induced opening of shipping routes increases the Arctic maritime traffic which exposes the area to negative impacts of potential maritime accidents. Still, quantitative analyses of the likely environmental impacts of such accidents are scarce, and our understanding of the uncertainties related to both accidents and their consequences is poor. There is an obvious need for analysis tools that allow us to systematically analyze the impacts of oil spills on Arctic species, so the risks can be taken into account when new sea routes or previously unexploited oil reserves are utilized. In this paper, an index‐based approach is developed to study exposure potential (described via probability of becoming exposed to spilled oil) and sensitivity (described via oil‐induced mortality and recovery) of Arctic biota in the face of an oil spill. First, a conceptual model presenting the relevant variables that contribute to exposure potential and sensitivity of key Arctic marine functional groups was built. Second, based on an extensive literature review, a probabilistic estimate was assigned for each variable, and the variables were combined to an index representing the overall vulnerability of Arctic biota. The resulting index can be used to compare the relative risk between functional groups and accident scenarios. Results indicate that birds have the highest vulnerability to spilled oil, and seals and whales the lowest. Polar bears’ vulnerability varies greatly between seasons, while ice seals’ vulnerability remains the same in every accident scenario. Exposure potential of most groups depends strongly on type of oil, whereas their sensitivity contains less variation. As the climate change is extending the ice‐free period in the Arctic, intensifying maritime traffic is increasing the risk of an oil spill (AMAP 2010, Ho 2010, Carson and Peterson 2016). Oil spills are considered the most significant threat to Arctic seas posed by maritime traffic (Arctic Council 2009), but assessing the potential environmental impacts related to such accidents is difficult due to scarce empirical data (AMAP 1998, Nevalainen et al. 2017). Some of the impacts can be assessed using oil spill models such as SIMAP (French‐McCay 2004) and OSCAR (Reed et al. 1995), but generally these models have limitations in Arctic context. They typically require detailed spatiotemporal data on, for example, weather, currents, and species abundance, which limit their use to those regions and species in the Arctic for which