## 3 Results
### Experiment 2  
The _Prorocentrum_ sp. and _Phaeocystis antarctica_ responded differently to different light intensities (HL, L1, L2, and L3) (Figures 6 and 7). The Chl-a content of _Prorocentrum_ sp. increased from 15.25 \(\mu\)g L\({}^{-1}\) (\(\pm\)0.42) on Day 1 to 81.60 \(\mu\)g L\({}^{-1}\) (\(\pm\)2.15) on Day 16 in the HL treatment (Figure 6). The Fv/Fm ratio decreased remarkably from 0.45 (\(\pm\)0.02) on Day 1 to 0.01 (\(\pm\)0.01) on Day 16, whereas \(\alpha\)PSII remained almost constant throughout the experiment, varying from 8.24 to 8.05 (\(\pm\)0.24), except on Day 16 when it exhibited the lowest value of 5.98 (\(\pm\)0.21). The Chl-a content and Fv/Fm in the L1 treatment exhibited a similar trend to that in the HL treatment. The Chl-a content increased from 17.43 \(\mu\)g L\({}^{-1}\) (\(\pm\)0.36) on Day 1 to 113.53 \(\mu\)g L\({}^{-1}\) (\(\pm\)2.12) on Day 16, whereas Fv/Fm decreased from 0.51 (\(\pm\)0.03) on Day 1 to 0.09 (\(\pm\)0.02) on Day 16. The \(\alpha\)PSII values remained almost constant with very few fluctuations, varying between 8.51 (\(\pm\)0.18) and 7.81 (\(\pm\)0.18). In the L2 treatment, the Chl-a content ranged from 16.41 \(\mu\)g L\({}^{-1}\) (\(\pm\)0.31) on Day 1 to 157.29 \(\mu\)g L\({}^{-1}\) (\(\pm\)1.39) on Day 16, whereas Fv/Fm decreased from 0.52 (\(\pm\)0.03) on Day 1 to 0.20 (\(\pm\)0.02) on Day 16, presenting values higher than those obtained in the HL and L1 treatments. The \(\alpha\)PSII values increased slightly from 8.71 (\(\pm\)0.18) on Day 1 to 9.57 (\(\pm\)0.19) on Day 16, peaking at 11.42 (\(\pm\)0.20) on Day 11. In the L3 treatment with the lowest irradiance, the Chl-a content increased from 17.28 \(\mu\)g L\({}^{-1}\) (\(\pm\)0.13) on Day 1 to 171.24 \(\mu\)g L\({}^{-1}\) (\(\pm\)1.03) on Day 16. The Fv/Fm ratio decreased slightly from 0.52 (\(\pm\)0.02) on Day 1 to 0.26 (\(\pm\)0.02) on Day 16, whereas \(\alpha\)PSII remained constant during the first eight days (8.17-8.35), increasing up to 10.42-10.77 (\(\pm\)0.20) between Days 9 and 15, and reaching 9.67 (\(\pm\)0.19) at the end of the experiment. The total cell number increased from 41,000 to 517,500 cells mL\({}^{-1}\), 35,384 to 452,500 cells mL\({}^{-1}\), 31,111 to 465,000 cells mL\({}^{-1}\), and 55,000 to 267,500 cells mL\({}^{-1}\) in the HL, L1, L2, and L3 treatments, respectively, from the beginning to the end of the experiment (Figure 6). _Phaeocystis antarctica_ exhibited less variability than _Prorocentrum_ sp. under all light intensities (Figure 7). In the HL treatment, the Chl-a content increased from 7.48 \(\mu\)g L\({}^{-1}\) (\(\pm\)0.23) on Day 1 to 104.69 \(\mu\)g L\({}^{-1}\) (\(\pm\)1.35) on Day 16, whereas Fv/Fm ranged from 0.24 (\(\pm\)0.02) on Day 1 to 0.38 (\(\pm\)0.01) on Day 16. The \(\alpha\)PSII remained almost constant during the 16 days, ranging between 13.39 (\(\pm\)0.24) and 11.28 (\(\pm\)0.21). In the L1 treatment, the Chl-a content increased from 8.27 \(\mu\)g L\({}^{-1}\) (\(\pm\)0.23) on day 1 to 120.15 \(\mu\)g L\({}^{-1}\) (\(\pm\)1.24) on Day 16, with Fv/Fm ranging between 0.23 (\(\pm\)0.01) and 0.38 (\(\pm\)0.02), consistent with that observed in the HL treatment, albeit with less variability. The \(\alpha\)PSII remained constant at \(\sim\)15.9 for the first 10 days, before increasing to 18.41 (\(\pm\)0.23) on Day 13, and then reaching 13.24 (\(\pm\)0.21) at the end of the experiment. In the L2 treatment, the Chl-a content increased from 8.46 \(\mu\)g L\({}^{-1}\) (\(\pm\)0.13) on Day 1 to 136.41 \(\mu\)g L\({}^{-1}\) (\(\pm\)1.35) on Day 16, while Fv/Fm increased from 0.29 (\(\pm\)0.01) to 0.36 (\(\pm\)0.02). The \(\alpha\)PSII increased from 14.43 (\(\pm\)0.25) to 18.26 (\(\pm\)0.31) during the first 11 days, and then decreased slightly to 15.65 (\(\pm\)0.27) on Day 16. In the L3 treatment, the Chl-a content remained low in the first seven days, ranging from 8.46 \(\mu\)g L\({}^{-1}\) (\(\pm\)0.13) to 13.70 \(\mu\)g L\({}^{-1}\) (\(\pm\)1.30), and then increased remarkably to 169.01 \(\mu\)g L\({}^{-1}\) (\(\pm\)0.30) on Day 16.