A Novel Invertebrate Predator on an Oceanic Island: Impacts and Invasion Dynamics of <scp> <i>Kontikia andersoni</i> </scp> on Macquarie Island

Sub-Antarctic islands, characterised by high endemism and invertebrate-dominated terrestrial ecosystems, hold significant conservation value and are vulnerable to biological invasion. On Macquarie Island, the invasive terrestrial flatworm <i>Kontikia andersoni</i> poses a threat to native biodiversity and ecosystem functioning. To determine the impacts of this invasive predator on native invertebrate communities, we examined species co-occurrence data and community composition from multiple sites across the island. Our findings indicate that at higher elevations where <i>K. andersoni</i> is present, there are significant reductions in invertebrate richness. Additionally, of the abiotic factors tested, slope and topographically deflected wind speed explained the highest amount of variation in flatworm distribution. Habitat suitability modelling identified areas at risk of invasion, providing targets for future biosecurity surveys. This study enhances our understanding of <i>K. andersoni</i> invasion dynamics and informs conservation efforts on Macquarie Island.