Effectiveness of two western Iberian Peninsula marine protected areas in reducing the risk of macroalgae invasion

Marine ecosystems are facing major anthropogenic disturbances, including loss of biodiversity, eutrophication, and biological invasions. Thus, attention has raised on marine conservation actions to preserve habitat resilience and biodiversity. Marine Protected Areas (MPAs) play an essential role in marine conservation as they are usually designated to provide marine ecosystem resilience of native communities to human-induced impacts (including non-native introductions) while contributing with positive effects on other ecosystem services. The introduction of a new species in novel marine habitats has been attributed to biotic, abiotic, and anthropogenic factors. In the present study, the effects of native functional diversity, wave exposure were studied, and for the first time, marine protection was addressed concerning the invasion success of six macroalgae in two MPAs in the NW Iberian Peninsula. The correlation between the presence/absence of some native functional groups and the invasion success of some invasive species highlighted the importance of conserving native canopy-formers. Despite local differences, wave exposure did not affect invasion success. The protection provided by both MPAs was very limited to prevent the establishment and spread of the most abundant invasive macroalgae. Therefore, stricter management plans should be implemented to ensure native ecosystem resilience within the MPAs.