Research project Spatially cascading regime shifts

Ecosystem regime shifts are often studied from a temporal perspective, but theory predicts that shifts typically start in the most vulnerable areas and then gradually spread in space, like infectious disease, financial crisis and revolts. In this project we identify the drivers behind, and spatiotemporal dynamics of, a regime shift in the Baltic Sea from dominance of large fish (perch, pike) to dominance of their prey fish, three-spined stickleback. The shift may have been triggered by overfishing and climate change, started in the outer archipelago in the early 2000s, and currently spreads towards the mainland coast like a ‘stickleback wave’. We combine environmental data collected since the early 1980s with theory and methods developed for modeling cascading changes through social networks, to identify i) the triggers of the shift, ii) how local context and/or connectivity between area explains how the shift spreads, and iii) what actions could reverse the shift.