Effect of UV-B radiation on the growth and antioxidant enzymes of Antarctic sea ice microalgae Chlamydomonas sp. ICE-L

The effect of ultraviolet-B (UV-B) radiation on Antarctic phytoplankton has become an attractive ecological issue as a result of annual springtime ozone depletion. The effects of UV-B radiation on the growth and antioxidant enzymes were investigated using Antarctic sea ice microalgae Chlamydomonas sp. ICE-L as the material in this study. The results demonstrated that UV-B radiation could notably inhibit the growth, especially at high UV-B radiation intensity (70 μW cm^-2). Malondialdehyde and O₂^·- content in ICE-L increased rapidly in early days (1-3 days) exposed to UV-B radiation enhancement, then decreased rapidly. In the stress of UV-B radiation enhancement, the superoxide dismutase, peroxidase and Catalase activities of 1-4 days in ICE-L were obviously higher than those in the control, and their activities became higher at high UV-B radiation intensity (70 μW cm^-2). These enzymes activity of 7 days would kept stable at low UV-B radiation intensity (35 μW cm^-2), but kept high level at high UV-B radiation intensity (70 μW cm^-2). However, the ascorbate peroxidase activity in ICE-L kept stable under the stress of UV-B radiation enhancement. The above experimental results indicated that the antioxidant enzyme system played an important role in the adaptation of Antarctic ice microalgae under the UV-B radiation change of Antarctic ecosystems.