Island Invader: Rugulopteryx okamurae and the Challenge for Macaronesian Coasts

ABSTRACT Since 2015, Rugulopteryx okamurae , a brown seaweed native to the Northwest Pacific, has become one of the most conspicuous marine invaders in the European continental coastal waters. Its recent establishment in the Macaronesian archipelagos (the Azores, Madeira and Canary Islands) has produced significant ecological changes, including displacement of native macroalgae and other benthic assemblages, as well as shifts in epifaunal and fish communities. Operational impacts from drifted and stranded biomass have also been reported locally, particularly in the Azores and Canaries, disrupting key human activities, including artisanal and commercial fisheries, coastal recreation and tourism, but with the socio‐economic costs remaining poorly quantified. This review synthesises the current ecological knowledge of R. okamurae invasion, history, ecology, impacts and management across the Macaronesian archipelagos. We evaluate the effectiveness and limitations of existing management interventions, which are already outlined in regional and national guidance documents, such as Spanish and Portuguese management strategies, including surveillance, manual and mechanical removal, biosecurity controls and early detection systems, and explore opportunities for valorising the harvested biomass. Building on these insights, we propose a regionally coordinated management framework that integrates early detection, cross‐island governance, adaptive mitigation measures, sustainable biomass utilisation and long‐term ecological monitoring. We also identify key research priorities, including understanding dispersal pathways, long‐term community shifts, interactions with climate change and the efficacy of mitigation strategies. Addressing the R. okamurae invasion will require a proactive, evidence‐based and collaborative management approach to safeguard ecosystem integrity, protect economic interests and bolster the resilience of Macaronesian coastal communities.