Impacts of enhanced UVB radiation on photosynthetic characteristics of the marine diatom Phaeodactylum tricornutum (Bacillariophyceae, Heterokontophyta)

• Published in: Journal of applied phycology 2017-06, Vol.29 (3), p.1287-1296
• Main Authors: Shi, Kunpeng, Yu, Jia, Liu, Chengyue, Xu, Zhimeng, Tang, Xuexi
• Format: Article
• Language: English
• Subjects: Adaptation; Anthropogenic factors; Biomedical and Life Sciences; Carotenoids; Chlorophyll; Chlorophylls; Diatoms; Earth; Earth surface; Ecology; Efficiency; Electron transport; Energy dissipation; Energy exchange; Exposure; Fluorescence; Freshwater & Marine Ecology; Human influences; Irradiance; Life Sciences; Parameters; Photochemicals; Photochemistry; Photosynthesis; Photosystem II; Plant Physiology; Plant Sciences; Respiration; Ultraviolet radiation
• ISSN: 0921-8971; 1573-5176
• DOI: 10.1007/s10811-017-1067-9

Solar ultraviolet B (UVB) irradiance at the Earth’s surface is increasing due to anthropogenic influences. To evaluate the effects of enhanced UVB radiation on photosynthetic characteristics of the marine diatom Phaeodactylum tricornutum , the species was exposed to four levels of UVB radiation, 0, 0.25, 0.75, and 1.50 KJ m −2  day −1 for 7 days. Effects of UVB stress on net photosynthetic rate, net respiration rate, variable chlorophyll (Chl) fluorescence parameters, Chl a and carotenoid contents, and UV-absorbing compounds (UVACs) were investigated. Results showed that there were no significant differences in terms of net respiration rate or maximal photochemical efficiency of photosystem II (F v /F m ) between the treatments in the short or long term. However, enhanced UVB radiation at an intensity of 0.16 W m −2 had a negative effect on the net photosynthetic rate, electron transport rate, and on the pathway of excess energy dissipation over the short term (1 to 5 days). Carotenoid and UVACs content increased under UVB radiation. Photosynthetic parameters were unaffected by UVB radiation on the seventh day indicating that P . tricornutum can adapt to UVB radiation in the long term. Results of the present study indicate that there is a dynamic balance between damage and adaptation in microalgae that enables them to adapt to UVB-induced photosystem alterations during both short-term and long-term exposure.