The potential of offshore wind farms to spread marine alien species

Summary

Alien species are organisms introduced to new areas through human activities that have been associated with artificial structures in coastal zones. Offshore wind farms (OWFs), rapidly expanding across marine environments, provide novel artificial surfaces that may facilitate the establishment and spread of alien species in regions lacking natural habitats. In the southern North Sea, offshore energy structures already support such species, with similar patterns observed globally. Despite international and national policies calling for better understanding of alien marine species, their pathways, and early detection systems, Norway lacks an understanding of how OWFs will impact the spread of alien marine species. The impact of OWFs on alien species spread remains understudied globally. This study synthesizes current knowledge and explores three mechanisms by which OWFs may promote alien species dispersal to Norway: (1) acting as stepping-stones for regional and international spread, (2) enabling hitchhiking on vessels and structures between offshore and inshore areas, and (3) creating refuges for alien species due to fishing restrictions within OWFs. We highlight relevant alien taxa for each and identify knowledge gaps, aiming to support biodiversity protection efforts and meet national and commercial obligations.