Increased invasion risk in a warmer world: Modeling the range expansion of three of the most problematic aquatic invasive plants in the United States with climate change using MaxEnt

Background/Question/Methods

Biological invasions and climate change pose two of the most important challenges facing the world throughout the next century. As climate change continues to alter native ecosystems, both the species richness of invaders and the total area invaded are expected to increase in the United States. Of particular importance are aquatic invasive plants, which have caused extensive economic and environmental impacts by drastically altering native biodiversity and the nutrient flow of freshwater ecosystems. Here we modeled the range expansion, in the United States, of three aquatic invasive plants: Alternanthera philoxeroides, Limnophila sessiliflora, and Salvinia molesta, under current, 2030-2059 (2040), and 2070-2099 (2080) climate conditions. We used the maximum entropy model, Maxent, to model the range expansion of these three species throughout the continental United States, using eight environmental variables. Future climate scenarios were determined using seven atmosphere-ocean general circulation models (AOGCMs), and regions that had the most overlap between models where considered high-risk areas for future invasions of these three species. All areas of future suitability were assessed using a 10 percentile threshold and a lowest presence threshold (LPT). In addition, we analyzed the habitat preference of each species to identify local habitats at risk for invasion. 

Results/Conclusions

The results of this study show that, under current, 2040, and 2080 climate scenarios, areas farther north are climatically suitable for A. philoxeroides, L. sessiliflora, and S. molesta to establish. By the 2080 scenario, the Northeast is at high risk for invasion by A. philoxeroides and S. molesta, while L. sessiliflora does not have as far of a northward expansion as the other species. The habitat preference analysis indicated that lakes and ponds are at increased risk for future invasion. Furthermore, A. philoxeroides and S. molesta were found significantly closer to rivers/streams than L. sessiliflora. The inability of L. sessiliflora to establish in habitats close to rivers/streams could limit how rapidly it will disperse to nearby locations, thereby resulting in its more contracted invaded range. These results show that with climate change, and consequently, warmer winters, these three aquatic invaders have the ability to expand their ranges throughout the continental United States, increasing their economic and ecological impacts. In order to prevent detrimental impacts of these species, land managers in the Northeastern United States should concentrate early detection and rapid response management of these species in lakes and ponds at high-risk.