Global change effects have favoured the introduction of new species in marine ecosystems in recent years. Gracilaria vermiculophylla, a red seaweed native from the north-eastern Pacific, has successfully colonised large regions in the Northern Hemisphere. In this research, we implemented species distribution models (SDMs) to (i) examine which were the most important environmental factors defining the presence of G. vermiculophylla at a global scale, and (ii) determine the potential current and future distribution of G. vermiculophylla based on two climate scenarios (representative concentration pathways (RCP 2.6 and RCP 8.5)). Our results suggest that temperature and salinity were the most important variables explaining the distribution of the target species. Additionally, the SDMs for present climate settings showed a potential wider distribution than is recorded to date. In addition, a subtle habitat expansion of 2.9° into higher latitudes was reported under the RCP 2.6 scenario by the end of this century. The high-carbon-emission scenario (RCP 8.5) delivered a potential large habitat expansion (6.0°), even reaching arctic latitudes, and a remarkable habitat loss of 11° in its southern distribution range. SMDs also forecasted suitable areas for this species in the Southern Hemisphere, pointing toward a potential global expansion in the coming decades.

The introduction of new species in marine ecosystems is a phenomenon that has grown in recent years due to anthropogenic activities and climate change effects. Agarophyton vermiculophyllum, a red seaweed native from the north-eastern Pacific, has successfully colonised large regions in the Northern Hemisphere; however, there are no studies to date investigating how future climate conditions will affect its potential biogeographical range. In this investigation, we implemented species distribution models (SDMs) based on sea surface temperature (SST) and salinity to determine the potential current, and future distribution of A. vermiculophyllum based on two climate scenarios (Representative Concentration Pathways [RCP 2.6 and RCP 8.5]). The model built for A. vermiculophyllum showed a high discriminatory ability and marked sensitivity. The SDM for present climate settings showed a potential wider distribution than is recorded to date. In addition, a subtle habitat expansion of 2.9º into higher latitudes was reported under the RCP 2.6 scenario by the end of this century. The high carbon emission scenario (RCP 8.5) delivered a potential large habitat expansion (6.0º), even reaching arctic latitudes. Under this climate scenario, it was also observed a remarkable habitat loss of 11° in its southern distribution range. SMDs also forecasted suitable areas for this species in the Southern Hemisphere, pointing toward a potential global expansion in the coming decades. The information reported in this study is relevant to developing management plans to effectively implement contingency actions addressing invasion events, thereby fostering adequate habitat conservation policies.