Zarah Pattison1, Hannah Hamilton1, Nigel Willby1, Wayne Dawson2 and Lynsey Bunnefeld1
1University of Stirling, Biological and Environmental Sciences, Stirling, FK9 4LA, Scotland, UK
2Durham University, Department of Biosciences, Durham, DH1 3LE, England, UK
Freshwater ecosystems, crucial to humanity, are in crisis and require immediate attention. Freshwater biodiversity has suffered a staggering 83% decline since 1970, a rate far exceeding that of marine or terrestrial systems. In addition, one in three of the 28,000 species dependent upon freshwater habitats are considered to be threatened with extinction. Although biological invasions are one of the greatest modern threats to biodiversity, a global assessment of freshwater invasions and how they vary geographically, is still lacking.
In order to quantify the current status of invasive alien plants in freshwater ecosystems globally, we integrated multiple global datasets such as the Global Naturalized Alien Flora (GloNAF) and the Global Inventory of Floras and Traits (GIFT). By categorizing invasive alien plant species as aquatic or terrestrial, we mapped the global distribution of aquatic invasive alien plants. These data show that aquatic alien plant species are more likely to become invasive, even though they represent <5% of alien flora. We used Structural Equation Modelling to identify which anthropogenic and background environmental variables drive the distribution of invasive alien species in freshwater habitats globally, and how this differs from terrestrial systems. Understanding these drivers will enable predictions of future invasion risk and promote the resilience of freshwaters.