Azaspiracid toxins are emerging dinoflagellate toxins, and the distribution pattern and climate change response mechanism of Azadinium spinosum, a key toxin-producing species, remain unclear in China's coastal waters. This study obtained distribution records of this species based on environmental DNA data from 600 stations in China's coastal waters during 2019-2024, and employed the MaxEnt model to predict its potential suitable habitat distribution under current conditions and three climate scenarios (SSP1-2.6, SSP2-4.5, and SSP5-8.5) for the 2050s and 2100s. The results showed that: (1) nitrate concentration (50.6%), sea surface temperature (28%), and silicate concentration (13%) were the dominant factors determining its distribution; (2) the current potential distribution area of the target species in China's coastal waters is mainly concentrated in the East China Sea and South China Sea, with a total area of 1.7136 million km², of which the South China Sea accounts for 56.04% and the East China Sea accounts for 36.23%; (3) under climate change scenarios, the potential distribution area of A. spinosum in China's coastal waters will shrink by 14.4%-33.6% by 2100; (4) its distribution may exhibit a "southern contraction and northern expansion" trend, with suitable habitats in the South China Sea decreasing by 0.1503-0.5213 million km², while those in the East China Sea and Yellow Sea increasing by 0.0556-0.3635 million km², and its distribution centroid potentially shifting northeastward from the northern South China Sea (116.98°E, 23.46°N) to the Yellow Sea (121.40°E, 28.78°N), with a maximum migration distance of 729.13 km. This study systematically reveals for the first time the distribution pattern of A. spinosum in China's coastal waters and the impacts of climate change on it, providing crucial scientific evidence for harmful algal bloom risk monitoring and management. 
 

Azadinium spinosum； MaxEnt model；climate change；species distribution；ecological risk