Relationship between antioxidant traits of Symbiodinium sp. symbiotic dinoflagellate extract under physicochemical factors during different seasons in Persian Gulf and Gulf of Oman

Coral bleaching, loss of symbiotic algae of Symbiodinium sp. or photosynthetic microalgae pigments from their coral host have become commonplace in recent decades due to the rising of sea temperatures and changes in physicochemical factors. It is essential to study the susceptibility of corals to bleaching, the physiology of its symbiotic algae, and its capacity to cope with abiotic stress. Oxidative stress is of particular importance due to the fact that it can be caused by photosynthetic dysfunction drived by temperature and other physicochemical factors. The aim of this study was to compare the effects of physicochemical factors on the photosynthetic performance of Symbiodinium sp. symbiosis with Stichodactyla haddoni in the Persian Gulf and the Gulf of Oman. To determine whether the cultured Symbiodinium sp. has different sensitivities to oxidative stress and whether winter and summer play a role in oxidative stress and coping with it, DPPH test and Freak ion reduction method (FRAP) were used and Physicochemical factors were measured through the HQ40D prototype device. Moreover, air data (wind speed) was obtained from the website www.irimo.ir. Statistical analysis was performed through one-way analysis of variance at the level of 0.05 and heatmap analysis. The results showed that the highest antioxidant capacity was assigned to Symbiodinium sp. extract in Chabahar in winter (IC50:135.768 μgr/ml) and the lowest antioxidant capacity was allocated to Chabahar in summer (IC50:349.090 μgr/ml). Ferric ion reduction of Symbiodinium sp. extracts showed the highest inhibition compared to ascorbic acid at a concentration of 2 mg/ml (0.297) and the lowest inhibition at a concentration of 0.063 mg/ml (0.015) in Chabahar in winter.