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.