Seasonal dynamics of antioxidant enzyme activity and photooxidative processes in the dominant macroalgal species of the Sea of Japan

Variations in the activity of the key antioxidant enzymes (superoxide dismutase, catalase, glutathione reductase, ascorbate peroxidase), as well as in the levels of lipid peroxidation (LP) and photosynthetic activity, were studied in five common species of macroalgae during their winter and summer vegetative season in the Sea of Japan. For most of the studied macroalgae, the highest intra-annual activities of antioxidant enzymes are observed during the colder months, while the lowest activities are observed during the warmer months. All the studied macroalgae display consistently high levels of photosynthesis during the period from December to February. A dramatic increase in the LP level and a suppression of photosynthetic activity are recorded during July and August for most of the studied macroalgae. The seasonal patterns of antioxidant enzyme activity and photooxidative processes in macroalgal tissues are discussed in terms of their regulation by fluctuations in illumination and seawater temperature in the habitats of the plants.