Climate warming and eutrophication threaten the habitat and conservation status of Ottelia acuminata var. acuminata in southwestern China

Climate warming and freshwater eutrophication threaten biodiversity in aquatic ecosystems, posing risks to threatened submerged macrophytes. Ottelia acuminata var. acuminata , an endemic submerged macrophyte and an important highland specialty aquatic vegetable resource in southwestern China, has declined markedly in multiple plateau lakes. Here, we integrated multi-source distribution records, water quality data, and bioclimatic variables from 2000 to 2023. Using a MaxEnt modeling framework, we assessed the spatiotemporal dynamics of potential habitat suitability and evaluated its associations with climatic and water quality factors. Our results showed that the climate-water quality model outperformed the climate-only model, while adding the human footprint index did not consistently improve predictive performance. Over the 24-year period, its suitable habitat area decreased by 80%, from 1536 km 2 in 2000–308 km 2 in 2023. The contraction accelerated after 2019 and followed a “core persistence and peripheral contraction” pattern. This contraction was associated with rising bio10 (mean temperature of warmest quarter), shifts in bio3 (isothermality) beyond the species’ optimal range, and increasing variability in pH and turbidity in peripheral lakes, which together degraded its habitat. The probability-weighted habitat centroid also shifted 67.64 km eastward. According to the IUCN Red List criteria, our preliminary assessment indicates that the taxon meets the criteria for Vulnerable and is approaching the threshold for Endangered. These findings call for urgent, targeted measures and highlight the need to integrate climate and water quality information into spatially explicit conservation, habitat restoration, and sustainable management of this highland specialty aquatic vegetable resource.