EFFECTS OF TEMPERATURE ON FEEDING, GROWTH, ENZYME ACTIVITY AND INTESTINAL MICROBIOTA OF PROCAMBARUS CLARKII

To investigate the effects of temperature on the feeding, growth, enzyme activity, and intestinal microbiota of the red swamp crayfish (Procambarus clarkii), juveniles with an average weight of (3.80±0.05) g were selected and subjected to four temperature treatments (15℃, 20℃, 25℃, and 30℃). The results indicated that both daily feed intake and daily feeding rate increased with rising temperature, with the 30℃ group exhibiting a significantly higher feeding rate compared to the 15℃ and 20℃ groups. In terms of growth, the 25℃ group achieved the highest weight gain and specific growth rate, significantly surpassing the 15℃ group, while the 30℃ group displayed the highest molting rate and was also significantly higher than the 15℃ group. Enzyme activity analysis revealed that the 25℃ group showed significantly higher activities of digestive enzymes (protease and amylase) than the other temperature groups. Additionally, this group demonstrated significantly elevated levels of antioxidant (total antioxidant capacity, superoxide dismutase, catalase) and nonspecific immune enzymes (acid phosphatase, alkaline phosphatase) compared to the other groups, indicating enhanced stress resistance and immune capacity at 25℃. Intestinal microbiota analysis indicated that the 20℃ group had the highest microbial community richness (Observed OTUs, Chao1, Ace indices). However, at 25℃, significant alterations in community structure were observed at the phylum and genus levels: the relative abundances of Patescibacteria, Planctomycetota, and Bdellovibrionota decreased significantly. At the genus level, the beneficial Lysinibacillus increased significantly, while potential pathogens such as Candidatus Bacilloplasma, Shewanella, Pseudomonas, and Pseudoxanthomonas decreased significantly. These findings suggest that 25℃ is conducive to the growth of P. clarkii, enhancing its digestive enzyme activity, immune function, disease resistance, and significantly improving the intestinal microbiota structure.