Combined effects of water temperature and copper ion concentration on catalase activity in Crassostrea ariakensis

A central composite experimental design and response surface method were used to investigate the combined effects of water temperature （18-34℃） and copper ion concentration （0.1-1.5 mg/L） on the catalase （CAT） activity in the digestive gland of Crassostrea ariakensis. The results showed that the linear effects of temperature were significant （P〈0.01）, the quadratic effects of temperature were significant （P〈0.05）, the linear effects of copper ion concentration were not significant （P〉0.05）, and the quadratic effects of copper ion concentration were significant （P〈0.05）. Additionally, the synergistic effects of temperature and copper ion concentration were not significant （P〉0.05）, and the effect of temperature was greater than that of copper ion concentration. A model equation of CAT enzyme activity in the digestive gland of C. ariakensis toward the two factors of interest was established, with R2, Adj. R2 and Pred. R2 values as high as 0.943 7, 0.887 3 and 0.838 5, respectively. These findings suggested that the goodness of fit to experimental data and predictive capability of the model were satisfactory, and could be practically applied for prediction under the conditions of the study. Overall, the results suggest that the simultaneous variation of temperature and copper ion concentration alters the activity of the antioxidant enzyme CAT by modulating active oxygen species metabolism, which may be utilized as a biomarker to detect the effects of copper pollution.