Global warming has led to rising water temperatures, posing a significant threat to fish survival. Understanding the mechanisms through which fish respond to and adapt to temperature variations is thus of considerable importance. This study employed high-throughput 16S rRNA gene sequencing and bioinformatics to investigate changes in the intestinal microbiota of the kaluga sturgeon (Huso dauricus) under four temperature conditions (19℃, 25℃, 28℃, and 31℃) and its relationship with adaptation to high-temperature stress. The results indicated that temperature variations caused significant changes in the intestinal microbiota. Over time, differences in microbiota structure became more pronounced under different temperature conditions, and within-group variability gradually decreased. At higher temperatures, the relative abundance of Sphingomonas significantly decreased, while Clostridium sensu stricto 1, Cetobacterium, and Plesiomonas exhibited a significant increase in relative abundance. Upon cessation of rapid mortality under various high-temperature conditions, the intestinal microbiota structure and composition became highly similar, with Clostridium sensu stricto 1 dominating both in terms of composition and relative abundance, suggesting a central role in adaptation to high-temperature stress. This study preliminarily confirms that the high-temperature adaptability of Huso dauricus is closely related to the structure and composition of its intestinal microbiota, with bacteria such as Clostridium sensu stricto 1 playing an important role. These findings provide new scientific insights into enhancing fish adaptability to high-temperature stress.
 

high-temperature stress,Huso dauricus,intestinal microbiota,high-temperature adaptability