Global invasion dynamics of marine macroalgae: ecological impacts, vectors of spread, and management challenges

Abstract

Marine macroalgae play critical ecological and socioeconomic roles in coastal ecosystems, yet the global proliferation of non-indigenous macroalgal taxa poses a significant threat to marine biodiversity and habitat integrity. This mini-review synthesizes contemporary research on the most prominent invasive marine macroalgae worldwide, including Undaria pinnatifida, Sargassum muticum, Caulerpa spp., Asparagopsis spp., and the rapidly expanding Rugulopteryx okamurae. The literature reveals that while these species share highly competitive life-history traits, their invasion success and ecological impacts are highly context-dependent and density-driven. Direct consequences range from severe community simplification, shading, and spatial exclusion of native biota to subtle, localized alterations and unexpected facilitative interactions. Anthropogenic activities - predominantly shipping, aquaculture, and climate-induced warming - serve as primary vectors for primary introduction and secondary spread, complemented by localized biological vectors. Given the high economic and ecological costs associated with eradication post-establishment, management strategies are increasingly shifting toward predictive risk mapping, mechanism-based monitoring, and the preservation of native canopy integrity to mitigate disturbance-mediated invasions.