3.1Physiological response
The physiological response of Turbinaria peltata to MHWs stress
was remarkable (Fig. 2). After the first MHWs, the density of
zooxanthellae reduced about 79.44 % compared to the control group, and
the concentration of Chl a decreased about 33.67 %. While, the
levels of GST, Caspase-3, SOD, and CAT showed a significant
increase. The effect of the second
MHWs was less intense, as indicated by the slight decrease in density of
zooxanthellae and concentration of Chl a , which showed about
69.71% and 17.63% decrease compared to the control group,
respectively. Although there was an increase in levels of GST,
Caspase-3, SOD, and CAT, it was not as high as those of the first heat
stress. Compared to the first heat stress, the levels of GST and
Caspase-3 exhibited a significant decrease (p < 0.05), and the
levels of CAT and SOD also decreased although it’s not significant.
Fig. 2. Response of coral physiological indicators under different
treatments. a: zooxanthellae, b: Chl a, c: GST, d: Caspase-3, e: CAT, f:
SOD.