Contrasting invasion risks of Pomacea canaliculata and Pontederia crassipes under future climate change in the middle and lower reaches of Yangtze River

The invasion and spread of alien aquatic organisms pose an increasing threat to ecosystem stability and functioning, biodiversity conservation, and socioeconomic development under ongoing climate change. However, limited attention has been given to the compound ecological risks of multi-species invasions driven by the combined effects of climate factors, topography, water quality, vegetation, and other environmental variables under future climate scenarios. Focusing on Pomacea canaliculata (P. canaliculata) and Pontederia crassipes ( P. crassipes ), this study employed the MaxEnt model and spatial analysis to identify key environmental determinants and to project current and future habitat suitability in the middle and lower reaches of the Yangtze River Basin under SSP245 and SSP585 scenarios. The results show that the MaxEnt model performed with high accuracy for P. crassipes (AUC = 0.954) and good accuracy for P. canaliculata (AUC = 0.880). Temperature-related variables predominantly constrained the distribution of P. crassipes , with a cumulative contribution of 44.2%, particularly isothermality and temperature seasonality, whereas P. canaliculata was jointly influenced by terrain factors and thermal conditions, with contribution rates of 40.5% and 23.3%, respectively. In terms of current habitat distribution, P. canaliculata (28.23 × 10 4 km 2 ) occupies a larger range than P. crassipes (5.77 × 10 4 km 2 ), with P. canaliculata exhibiting a widespread distribution mainly concentrated in the Hanjiang Plain and the Jiangsu-Anhui coastal plains, whereas P. crassipes follows a belt-like distribution pattern, primarily spreading in Poyang Lake and the Yangtze River Delta. From 2021 to 2100, the suitable habitat of P. canaliculata is projected to expand under both SSP245 and SSP585 scenarios, with a more extensive and rapid expansion under the high-emission scenario (SSP585) (reaching 35.06 × 10 4 km 2 during 20 4 1–2060, an increase of 6.83 × 10 4 km 2 from present) High-suitability areas display an overall increasing trend, whereas moderate- and low-suitability areas exhibit marked inter-period fluctuations. In contrast, the suitable habitat of P. crassipes follows a trend of initial expansion followed by contraction under both climate scenarios, reaching the maximum total area during 2041–2060 under SSP245 (8.11 × 10⁴ km²) and SSP585 (6.81 × 10⁴ km²). After 2060, the suitable habitat begins to decrease and will significantly shrink to its current level during 2081–2100. The contrasting responses of the two species highlight the necessity for species-specific and climate-adaptive management strategies. Integrating climate projections with habitat suitability modeling can enhance early warning systems and support risk-based management of aquatic biological invasions in large aquatic ecosystems.