Distribution Shifts of Acanthaster solaris Under Climate Change and the Impact on Coral Reef Habitats

Pacific crown-of-thorns starfish (<i>Acanthaster solaris</i>) outbreaks pose a significant threat to coral reef ecosystems, with climate change potentially exacerbating their distribution and impact. However, there remains only a small number of predictive studies on how climate change drives changes in the distribution patterns of <i>A. solaris</i>, and relevant assessments of the impact of these changes on coral reef areas are lacking. To address this issue, this study investigated potential changes in the distribution of <i>A. solaris</i> under climate change and its impact on <i>Acropora</i> coral habitats. Using a novel two-step framework, we integrated both abiotic and biological (<i>Acropora</i> distribution) predictors into species distribution modeling to project future shifts in <i>A. solaris</i> habitats. We created the first reliable set of current and future global distribution maps for <i>A. solaris</i> using a comprehensive dataset and machine learning approach. The results showed significant distribution shifts under three climate change scenarios (SSP1-2.6, SSP2-4.5, and SSP5-8.5), with expanded ranges under all scenarios, and the greatest expansion occurring near 10° S. Asymmetry in the latitudinal shifts in habitat boundaries suggests that the Southern Hemisphere may face a more severe expansion of <i>A. solaris</i>. Regions previously unsuitable for <i>A. solaris</i>, such as parts of New Zealand, might experience new invasions. Additionally, our findings highlight the potential increase in predatory pressure on coral reefs under SSP2-4.5 and SSP5-8.5 scenarios, particularly in the Western Coral Triangle and Northeast Australian Shelf, where an overlap between <i>A. solaris</i> and <i>Acropora</i> habitats is significant. This study provides critical insights into the ecological dynamics of <i>A. solaris</i> in the context of climate change, and the results have important implications for coral reef management. These findings highlight the need for targeted conservation efforts and the development of mitigation strategies to protect coral reefs from the growing threat posed by <i>A. solaris</i>.