title: Faster recovery of a diatom from UV damage under ocean acidification.
abstract: Diatoms are the most important group of primary producers in marine ecosystems. As oceanic pH declines and increased stratification leads to the upper mixing layer becoming shallower, diatoms are interactively affected by both lower pH and higher average exposures to solar ultraviolet radiation. The photochemical yields of a model diatom, Phaeodactylum tricornutum, were inhibited by ultraviolet radiation under both growth and excess light levels, while the functional absorbance cross sections of the remaining photosystem II increased. Cells grown under ocean acidification (OA) were less affected during UV exposure. The recovery of PSII under low photosynthetically active radiation was much faster than in the dark, indicating that photosynthetic processes were essential for the full recovery of photosystem II. This light dependent recovery required de novo synthesized protein. Cells grown under ocean acidification recovered faster, possibly attributable to higher CO₂ availability for the Calvin cycle producing more resources for repair. The lower UV inhibition combined with higher recovery rate under ocean acidification could benefit species such as P.tricornutum, and change their competitiveness in the future ocean.
authors.affiliation: State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China.
authors.forename: Yaping
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Biology Department, Mount Allison University, Sackville, New Brunswick, Canada.
authors.forename: Douglas A
authors.initials: DA
authors.lastname: Campbell
authors.affiliation: State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China. Electronic address: ksgao@xmu.edu.cn.
authors.forename: Kunshan
authors.initials: K
authors.lastname: Gao
mesh_terms: D002245:Carbon Dioxide / Q000494:pharmacology; D017377:Diatoms / Q000166:cytology / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects*; D006863:Hydrogen-Ion Concentration; D010788:Photosynthesis / Q000187:drug effects / Q000528:radiation effects; D012623:Seawater / Q000737:chemistry*; D013997:Time Factors; D014466:Ultraviolet Rays / Q000009:adverse effects*
chemical_list: D002245:Carbon Dioxide
keywords: Ocean acidification; Ocean stratification; Photoinhibition; Photosystem II; UV radiation