Offshore marine renewable energy devices as stepping stones across biogeographical boundaries

Summary Offshore renewable energy provides an increasing component of our electricity supply. We have limited understanding of the potential environmental impacts of these developments, particularly in the move to larger scales. Surfaces provided by devices offer novel habitat to marine organisms, which may allow species to spread to new areas. We used coupled biological and hydrodynamic models to investigate the spread of intertidal marine organisms with pelagic larvae (such as barnacles or gastropods) in the region around south‐western S cotland. We assessed the impact of novel habitat on dispersal and its role in allowing transgression of physical barriers. Model renewable energy device sites provided habitat for pelagic larval particles that would otherwise have been lost offshore. They also provided a source of larvae for existing coastal sites. Many offshore devices fulfilled source and destination (or intermediate connection) roles, creating new dispersal pathways, and allowing previously impossible northward dispersal from the N orthern I rish coast to S cotland. Synthesis and applications . New habitat close to biogeographical barriers has implications for existing species’ distributions and genetic population structure. It also affects the spread of non‐native species and ‘climate migrants’. Monitoring these sites for the presence of such species will be important in determining the future ecology of coastal habitat and in maintaining economic aquaculture and marina operations. Future model studies should focus on particular species of importance, taking account of their biology and current distribution.