海水pH变化下大亚湾海域典型海藻对升温的生理响应OA

To investigate the physiological responses of macroalgae to warming under different pH con-ditions,the effects of temperature rise on the photosynthetic physiology of three typical macroalgae,namely the green alga Ulva lactuca,the red alga Gracilaria chilensis and the brown alga Sargasum graminifolium were comparatively studied in Daya Bay.The results showed that the maximum photosynthetic oxygen evolution rate(Pmax)of U.lactuca at normal pH and temperature is(248.6±40.3)μmol/(g·h),which was reduced by 48%and 35%by increasing and decreasing pH,respectively.The Pmax of S.graminifoli-um[(86.4±11.2)μmol/(g·h)]showed no significant change with pH variation,but that of G.chilensis[(78.9±5.74)μmol/(g·h)]increased with decreasing pH.Accordingly,an increase/decrease in pH both reduced the saturation light(EK)of U.lactuca,but had no significant effect on G.chilensis.The EK of S.graminifolium also decreased with decreasing pH.These results also showed that an increase in seawater temperature(3℃)would increase the photosynthetic capacity of the three macroalgae species.The promo-tion of daily carbon fixation of U.lactuca by an increase in temperature firstly increased and then decreased when pH decreased from 8.6 to 7.8,while it varied less in G.chilensis and gradually increased in S.gra-minifolium.These findings contribute to a deeper understanding of the physiological response and acclima-tion of macroalgae to temperature rise in Daya Bay under conditions of ocean acidification or alkalization.