Table 1.
Physiological parameters study in N. salina under cold stress. Optical density measurements at 750 nm indicating cell density, were used to determine growth over the 96 h growth period, total cell count was monitored using counting chamber. Fv/Fm ratio and ETR values (at 285 µmol photons m−2·s−1) are listed for a 96 h time period. % Saturation of oxygen was calculated by normalizing dissolved oxygen (DO) values (ppm) with temperature, salinity and atmospheric pressure. All data points show average of triplicate along with standard errors. Statistical analysis was performed using SAS, where A, B, C, D represents statistically significant mean separation for differences between temperature on each day at p ≤ 0.05.
| Optical Density Measurements (750 nm) | ||||||||
|---|---|---|---|---|---|---|---|---|
| Temp/H | 25 °C | Post-Hoc | 15 °C | Post-Hoc | 10 °C | Post-Hoc | 5 °C | Post-Hoc |
| 0 | 0.46 ± 0.01 | A | 0.45 ± 0.01 | A | 0.44 ± 0.01 | A | 0.46 ± 0.01 | A |
| 24 | 0.51 ± 0.01 | A | 0.51 ± 0.00 | AB | 0.48 ± 0.03 | B | 0.49 ± 0.02 | AB |
| 48 | 0.53 ± 0.01 | A | 0.52 ± 0.02 | AB | 0.49 ± 0.02 | C | 0.47 ± 0.02 | BC |
| 72 | 0.57 ± 0.01 | A | 0.52 ± 0.02 | B | 0.50 ± 0.02 | B | 0.48 ± 0.02 | B |
| 96 | 0.60 ± 0.01 | A | 0.50 ± 0.01 | B | 0.51 ± 0.01 | B | 0.49 ± 0.02 | B |
| Total Cell count (per mL) | ||||||||
| 0 | 6.1 × 109 ± 3.9 × 108 | A | 5.1 × 109 ± 2.5 × 108 | A | 4.8 × 109 ± 1.0 × 107 | A | 4.7 × 109 ± 2.4 × 108 | A |
| 24 | 7.3 × 109 ± 5.5 × 108 | A | 6.3 × 109 ± 2.7 × 108 | A | 5.6 × 109 ± 5.1 × 107 | A | 5.5 × 109 ± 1.3 × 108 | A |
| 48 | 9.3 × 109 ± 4.0 × 108 | A | 7.2 × 109 ± 2.4 × 108 | B | 6.9 × 109 ± 2.4 × 108 | B | 6.1 × 109 ± 6.8 × 107 | B |
| 72 | 1.1 × 1010 ± 4.3 × 108 | A | 9.5 × 109 ± 1.1 × 108 | A | 7.6 × 109 ± 9.3 × 107 | B | 7.3 × 109 ± 2.2 × 108 | B |
| 96 | 1.4 × 1010 ± 5.1 × 108 | A | 1.2 × 1010 ± 5.1 × 108 | B | 9.5 × 109 ± 1.4 × 108 | C | 7.8 × 109 ± 2.9 × 108 | C |
| Photosynthetic Activity (Fv/Fm) | ||||||||
| 0 | 0.55 ± 0.02 | A | 0.55 ± 0.00 | A | 0.55 ± 0.01 | A | 0.54 ± 0.01 | A |
| 24 | 0.56 ± 0.00 | A | 0.55 ± 0.02 | AB | 0.55 ± 0.03 | AB | 0.48 ± 0.05 | B |
| 48 | 0.57 ± 0.01 | A | 0.54 ± 0.04 | B | 0.52 ± 0.05 | BC | 0.39 ± 0.10 | C |
| 72 | 0.57 ± 0.01 | A | 0.57 ± 0.01 | A | 0.56 ± 0.02 | A | 0.53 ± 0.02 | A |
| 96 | 0.56 ± 0.00 | A | 0.50 ± 0.01 | A | 0.39 ± 0.05 | B | 0.28 ± 0.07 | C |
| ETR Values (µmol photons m−2·s−1) | ||||||||
| 0 | 17.00 ± 3.23 | A | 14.13 ± 3.13 | A | 16.20 ± 2.33 | A | 17.83 ± 3.52 | A |
| 24 | 19.00 ± 1.61 | A | 11.47 ± 3.58 | A | 9.27 ± 2.22 | B | 8.87 ± 3.72 | AB |
| 48 | 15.30 ± 4.38 | A | 11.13 ± 2.45 | A | 11.07 ± 3.41 | B | 7.90 ± 1.80 | AB |
| 72 | 20.47 ± 4.72 | A | 12.77 ± 1.44 | A | 11.10 ± 2.57 | AB | 6.50 ± 1.33 | B |
| 96 | 15.80 ± 6.06 | A | 8.70 ± 1.55 | A | 8.37 ± 1.73 | B | 5.50 ± 1.40 | B |
| % Saturation of Oxygen | ||||||||
| 0 | 119.04 ± 3.41 | A | 86.37 ± 7.79 | B | 63.88 ± 4.86 | C | 70.76 ± 5.53 | C |
| 24 | 91.26 ± 3.66 | A | 88.99 ± 2.02 | A | 86.75 ± 4.68 | AB | 74.46 ± 5.34 | B |
| 48 | 89.51 ± 2.20 | A | 87.04 ± 3.71 | A | 86.44 ± 7.63 | A | 72.39 ± 6.72 | B |
| 72 | 96.43 ± 6.15 | A | 89.08 ± 2.01 | B | 88.38 ± 2.86 | B | 78.69 ± 2.28 | B |
| 96 | 93.29 ± 4.64 | A | 88.48 ± 2.39 | B | 89.50 ± 5.27 | AB | 69.85 ± 5.43 | C |