Fig 1.
Physiological responses of ocean acidification acclimatised U. linza to changes of seawater carbon chemistry and light exposure.
The blue-dotted and the red-solid symbols represent down- and up-regulated metabolic pathways respectively. PSI: Photosystem I; PSII: Photosystem II; Fd: ferredoxin; Fp: flavoprotein; OEC: oxygen- evolving complex; NPQ: non-photochemical quenching; CA: carbonic anhydrase.
Table 1.
Parameters of the seawater carbonate system at LC and HC.
Measurements and estimation of the parameters are described in Materials and Methods. Data are the means ± SD (n = 5). LC, the low pCO2 condition, HC, the high pCO2 condition, DIC = dissolved inorganic carbon, TA = total alkalinity. The unit of pCO2 is μatm and all other parameters’ unit is μmol kg-1.Different superscript letters indicate significant differences between two conditions (P < 0.05).
Fig 2.
Net photosynthetic rate of U. linza grown at ambient (LC; 390 μatm) and elevated (HC; 1000 μatm) CO2 levels and measured under different treatments (Control, added with Tris, AZ, and EZ).
Different superscript letters indicate significant differences between treatments within one culture condition (P < 0.05, one-way ANOVA and Tukey HSD test) and the lowercase and capital letters represent the comparisons at LC and HC, respectively. Asterisks indicate significant differences between culture conditions (P < 0.05, Independent samples t-tests).
Fig 3.
Relative growth rate of U. linza grown at ambient (LC; 390 μatm) and elevated (HC; 1000 μatm) CO2 levels.
Different superscript letters indicate significant differences between culture conditions (P < 0.05, Independent samples t-tests).
Fig 4.
Changes of net photosynthetic rates of U. linza grown at ambient (LC; 390 μatm) and elevated (HC; 1000 μatm) CO2 levels measured at different pH and light (LL, 100 μmol photons m-2 s-1; HL, 600 μmol photons m-2 s-1) conditions.
Table 2.
Three-way analysis of variance of the responses of the net photosynthetic rate in U. linza grown under LC and HC to various light and seawater pH levels.
LC, the low pCO2 condition, HC, the high pCO2 condition.
Fig 5.
rETR of U. linza grown at ambient (LC; 390 μatm) and elevated (HC; 1000 μatm) CO2 levels and measured at different light conditions (LL, 100 μmol photons m-2 s-1; HL, 600 μmol photons m-2 s-1).
Fig 6.
NPQ of U. linza grown at ambient (LC; 390 μatm) and elevated (HC; 1000 μatm) CO2 levels and measured at different light conditions (LL, 100 μmol photons m-2 s-1; HL, 600 μmol photons m-2 s-1).
Table 3.
Two-way analysis of variance of the effects of CO2 and light on rETR in U. linza.
Table 4.
Two-way analysis of variance of the effects of CO2 and light on NPQ in U. linza.
Fig 7.
Contents of Chl a and Chl b in U. linza grown at ambient (LC; 390 μatm) and elevated (HC; 1000 μatm) CO2 levels.
Different superscript letters indicate significant differences between culture conditions (P < 0.05, Independent samples t-tests).