Development of a Cumulative Impact Assessment tool for birds in Norwegian Offshore Waters: Trollvind OWF as a case study

Kate Layton-Matthews, Lila Buckingham, Emma Jane Critchley, Anna L. K. Nilsson, Victoria M. S. Ollus, Manuel Ballesteros, Signe Christensen-Dalsgaard, Nina Dehnhard, Per Fauchald, Frank Hanssen, Morten Helberg, Elizabeth Masden, Roel F. May, Hanno Sandvik, Arnaud Tarroux, Tone K. Reiertsen

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Development of a Cumulative Impact Assessment tool for birds in Norwegian Offshore Waters: Trollvind OWF as a case study. NINA Report 2295. Norwegian Institute for Nature Research. There is growing interest in the economic potential of marine areas for e.g., offshore renewables, fisheries, and shipping. Thus, the cumulative stress on marine ecosystems and the species inhabiting them is increasing. This is of particular concern for migratory birds and seabirds which are undergoing global declines. In the light of an expanding global market for offshore renewables, knowledge of their cumulative impacts combined with other human-derived pressures on marine populations is crucial. This is set against the backdrop of climate change and associated large-scale changes in our oceans. Achieving sustainable development, while mitigating the effects of climate change, requires effective tools to assess the cumulative impacts of anthropogenic stressors on ecosystems. Cumulative impact assessments for the marine environment are strongly influenced by an approach developed by Halpern et al. (2008). In this report, we present and demonstrate a beta-version of a cumulative impact assessment tool for marine industrial pressures on seabirds, which is being developed through the Research Council of Norway (RCN) -funded MARCIS project. The goal of MARCIS is to assess the impacts of marine anthropogenic pressures on seabirds in the North-East Atlantic, which will both utilise and further develop the Halpern formula and provide a publicly open web-based tool that acts as a decision support for marine spatial planning. Equinor has been exploring the potential for con-structing a floating offshore wind farm, called Trollvind, in the North Sea. This proposed floating wind farm is in the early planning stages of development and is proposed to be located around the Troll offshore oil and gas platforms, approximately 65 km west of Bergen. This report presents; 1) a summary of a scoping of existing data of birds using Norwegian offshore area, 2) an assessment of bird migration through the North Sea and the Trollvind area, and the likelihood that some bird groups will be more impacted by an offshore wind farm in this area, and 3) a demonstration of the tool under development (the MARCIS web application), where we assess the potential cumulative impact of the proposed Trollvind OWF development and ocean warming on two seabird populations, as a case study. This report has specific emphasis on the demonstration of the tool. Results of the scoping study of birds using the Norwegian offshore areas indicated a below-medium to medium sensitivity of waterbirds to wind farms in the Trollvind area. However, there were strong seasonal differences showing above-medium values in summer in the eastern and north-eastern parts of the area. Our results also revealed that migratory bird groups differ in their type of risks of impact associated with the Trollvind development, where migrating raptors, gulls, waterfowl and owls were at greatest risk of collision, while migrating seabirds, waterbirds and waders had a higher risk of displacement and/or barrier effects. In the demo of the tool, we estimated the cumulative impact of two stressors (Trollvind OWF and ocean warming) on two study populations (kittiwake breeding at Ålesund colony and common guillemot from Sklinna colony). Both their non-breeding distribution and the cumulative impact of the two stressors was visualised in the demo of the MARCIS App. The impact of Trollvind OWF was negligible for both populations, while disturbance led to a small reduction in guillemots’ body mass and consequently their survival rates. However, ocean warming had a larger population impact, given the high emissions scenario used to quantify impact weights, particularly for guillemots. However, it is important to keep in mind that this demonstration is a case study of only two populations and should be interpreted in the larger context of the results from the scoping study and bird migration studies. The extensive range of species using this area at different times of year are much larger, and this has implementations for a potentially broader impact of such offshore developments. This also highlights the need for both spatial explicit distribution data and demographic/population data to ensure an appropriate knowledge base of population impacts before any OWF developments are conducted.
Original languageEnglish
Number of pages66
Publication statusPublished - 2023


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