## 3 Results
### Experiment 1
antarctica_ & **DFB** & 0.28 & 0.44 & - & 0.01 & 0.02 & 0.53 & - & 0.01 & 0.01 & 1.20 & 1.89 & - & 0 \\  & **-B12** & 0.24 & 0.35 & - & 0.01 & 0.02 & 0.47 & - & 0.01 & 0.01 & 1.33 & 1.94 & - & 0 \\  & **-CIRL** & 0.26 & 0.38 & - & 0.01 & 0.02 & 0.42 & - & 0.01 & 0.01 & 1.11 & 1.63 & - & 0 \\ \hline Mixed culture & **DFB** & 0.21 & 0.48 & 0.62 & 0.02 & 0.01 & 0.73 & - & 0.01 & 0.01 & 1.52 & 3.51 & 0.85 & 0.00 \\  & **-B12** & 0.20 & 0.43 & 0.93 & 0.00 & 0.00 & 0.21 & - & 0.00 & 0.01 & 0.49 & 1.04 & 4.43 & 2.78 \\  & **-CIRL** & 0.08 & 0.37 & 0.88 & 0.00 & 0.00 & 0.21 & - & 0.00 & 0.01 & 0.56 & 2.45 & 4.19 & 0.00 \\ \hline  & **-(B)** & & & & & & & & & & & & & & \\ \hline  & **Lines** & **Chl-c/** & **Chl-c/** & **Perid/** & **Bu/** & **Fuco/** & **Hex/** & **Viola-like/** & **Luf/** & **B-car/** & **Hex/** & **Hex/** & **Hex/** & **D/(D4 + D0** \\  & **Growth** & **Chl-a** & **Chl-a** & **Chl-a** & **Chl-a** & **Chl-a** & **Chl-a** & **Chl-a** & **Chl-a** & **Chl-a** & **Chl-c** & **Chl-c** & **Period** & \(\mathbf{\times}\mathbf{100}\)** \\ \hline _Proenctrum sp._ & **HL** & - & 0.26 & 1.29 & - & - & - & 0.02 & 0.00 & 0.02 & - & - & - & 8.78 \\  & **L1** & - & 0.25 & 1.10 & - & - & - & 0.02 & 0.00 & 0.02 & - & - & - & 8.22 \\  & **L2** & - & 0.34 & 1.33 & - & - & - & 0.03 & 0.00 & 0.01 & - & - & - & 4.85 \\  & **L3** & - & 0.22 & 1.26 & - & - & - & 0.03 & 0.00 & 0.01 & -The response of _P. antarctica_ in the DFB treatment presented a differential trend as compared with the -B12 and CTRL treatments (Figure 4). In the DFB treatment, the Chl-a content ranged from 8.98 \(\mu\)g L\({}^{-1}\) (\(\pm\)0.34) on Day 1 to 196.98 \(\mu\)g L\({}^{-1}\) (\(\pm\)2.98) on Day 16. On the contrary, Fv/Fm decreased from 0.41 (\(\pm\)0.02) to 0.32 (\(\pm\)0.02) in the first five days, and then remained constant until the end of the experiment. The \(\sigma\)PSII at 440 nm increased from 15.98 nm\({}^{2}\) (\(\pm\)0.27) on Day 1 to 17.14 nm\({}^{2}\) (\(\pm\)0.29) on Day 16, peaking at 22.20 nm\({}^{2}\) (\(\pm\)0.31) on Day 8. The Chl-a content in the -B12 treatment presented the same trend as that in the DFB treatment, varying from 8.35 \(\mu\)g L\({}^{-1}\) (\(\pm\)0.34) on Day 1 to 160.68 \(\mu\)g L\({}^{-1}\) (\(\pm\)3.30) on Day 16. The Fv/Fm ratio ranged between 0.39 (\(\pm\)0.02) and 0.37 (\(\pm\)0.02) during the first five days, exhibiting relatively low variability, and then stabilized at -0.4 until the end of the experiment. The \(\sigma\)PSII at 440 nm increased from 14.49 nm\({}^{2}\) (\(\pm\)0.25) on Day 1 to 17.86 nm\({}^{2}\) (\(\pm\)0.30) on Day 16, exhibiting fluctuations throughout the experiment. The Chl-a content in the CTRL treatment showed values ranging from 8.28 \(\mu\)g L\({}^{-1}\) (\(\pm\)0.34) on Day 1 to 148.94 \(\mu\)g L\({}^{-1}\) (\(\pm\)3.20) on Day 16. The Fv/Fm ratio also exhibited the same trend as in the -B12 treatment, albeit with lesser fluctuations and values ranging from 0.37 (\(\pm\)0.02) on Day 1 to 0.40 (\(\pm\)0.02) on Day 16. The \(\sigma\)PSII at 440 nm was recorded as 16.38 (\(\pm\)0.28) on Day 1 and 16.04 (\(\pm\)0.28) on Day 16, peaking at 21.52 (\(\pm\)0.26) on Day 7 and at 19.65 (\(\pm\)0.21) on Day 9. The total cell number increased from 58,000 to 315,000 cells mL\({}^{-1}\), 45,000 to 230,000 cells mL\({}^{-1}\), and 48,000 to 252,500 cells mL\({}^{-1}\) in the DFB, -B12, and CTRL treatments, respectively, from the beginning to the end of the experiment. The pigment/Chl-a ratios obtained by HPLC analyses are  
Figure 4: Experiment 1. Changes in Chl-a concentration (\(\mu\)g L\({}^{-1}\)), Fv/Fm, and \(\sigma\)PSII (nm\({}^{2}\)) in _Phaeocystis antarctica_ under different treatments. presented in Table 1. The most significant differences were detected for Chl-c\({}_{2}\)/Chl-a and Hex/Chl-a ratios among treatments. The Chl-c\({}_{2}\)/Chl-a ratio was 0.44 (\(\pm\)0.01), 0.35 (\(\pm\)0.01), and 0.38 (\(\pm\)0.01), whereas the Hex/Chl-a ratio was 0.53 (\(\pm\)0.02), 0.47 (\(\pm\)0.02), and 0.42 (\(\pm\)0.01) in the DFB, -B12, and CTRL treatments, respectively.