Effects of climate change on the future distributions of the top five freshwater invasive plants in South Africa

• Climate change is predicted to shape the distribution of alien invasive plants.
• We reconstruct niche models of the top five alien freshwater plants in South Africa.
• We find that climate change will favor the spread of some aquatic plants.
• We also find evidence for range contraction for other plants.
• We call for integrating climate change in control measures of alien invasion.

A recent study shows that most aquatic alien plants in temperate cold climate are of tropical and subtropical origins and only those that can withstand cold climates become invasive. This suggests that a changing climate that becomes warmer may result in currently non-invasive alien plants becoming invasive in the future. To facilitate pre-emptive actions when controlling invasive aquatic plants in South Africa under climate change, we reconstructed predictive models for the five most damaging aquatic alien plants of freshwater systems in the country. We found evidence of contrasting shifts in species distribution ranges: the ranges of Myriophyllum aquaticum and Pistia stratiotes will contract, while Azolla filiculoides, Eichhornia crassipes, and Salvinia molesta will increase their future ranges with most suitable habitats found in the Western Cape province and along coastal areas. In addition, the predicted range contraction and expansion would result in some dams currently vulnerable to invasion becoming resilient while others that are currently resilient may become vulnerable due to climate change. These results can be used to develop future monitoring programs for aquatic ecosystems, prioritize control efforts, and raise public awareness on risks posed by these aquatic invasive plants, especially under future climate scenarios.