Table 2. Linear mixed effects models for measured productivity response variables.
| Parameter | Source |
Halodule uninervis |
Thalassia hemprichii |
||||
|---|---|---|---|---|---|---|---|
| df | F | p | df | F | p | ||
| Net primary production | pCO2 | 1 | 4.669 | 0.049 | 1 | 0.184 | 0.675 |
| Nitrate | 1 | 0.091 | 0.767 | 1 | 2.745 | 0.120 | |
| pCO2 × Nitrate | 1 | 0.721 | 0.410 | 1 | 3.648 | 0.077 | |
| Shoot respiration | pCO2 | 1 | 3.785 | 0.072 | 1 | 0.849 | 0.373 |
| Nitrate | 1 | 5.199 | 0.039 | 1 | 0.226 | 0.642 | |
| pCO2 × Nitrate | 1 | 1.861 | 0.194 | 1 | 1.756 | 0.206 | |
| Rhizome-root respiration | pCO2 | 1 | 1.818 | 0.199 | 1 | 3.082 | 0.101 |
| Nitrate | 1 | 8.593 | 0.011 | 1 | 0.584 | 0.458 | |
| pCO2 × Nitrate | 1 | 9.037 | 0.009 | 1 | 1.607 | 0.226 | |
| Growth rate (10 days) | pCO2 | 1 | 10.430 | 0.006 | 1 | 6.376 | 0.024 |
| Nitrate | 1 | 3.418 | 0.086 | 1 | 1.427 | 0.252 | |
| pCO2 × Nitrate | 1 | 0.003 | 0.961 | 1 | 1.575 | 0.230 | |
| Growth rate (24 days) | pCO2 | 1 | 19.218 | 0.001 | 1 | 0.068 | 0.799 |
| Nitrate | 1 | 1.014 | 0.331 | 1 | 0.870 | 0.367 | |
| pCO2 × Nitrate | 1 | 1.544 | 0.234 | 1 | 0.077 | 0.786 | |
| Sucrose phosphate synthase | pCO2 | 1 | 1.556 | 0.233 | 1 | 0.534 | 0.477 |
| Nitrate | 1 | 5.109 | 0.040 | 1 | 0.436 | 0.520 | |
| pCO2 × Nitrate | 1 | 0.275 | 0.608 | 1 | 0.062 | 0.806 | |
| Sucrose synthase | pCO2 | 1 | 0.002 | 0.967 | 1 | 3.619 | 0.078 |
| Nitrate | 1 | 1.677 | 0.216 | 1 | 0.389 | 0.543 | |
| pCO2 × Nitrate | 1 | 3.291 | 0.091 | 1 | 0.251 | 0.624 | |
| Total non-structural carbohydrates | pCO2 | 1 | 0.003 | 0.959 | 1 | 0.548 | 0.471 |
| Nitrate | 1 | 0.053 | 0.821 | 1 | 0.994 | 0.336 | |
| pCO2 × Nitrate | 1 | 0.152 | 0.702 | 1 | 4.66 × 10−4 | 1.000 | |
Variables were analysed with pCO2 as a continuous predictor and nitrate as a categorical factor. Individual aquarium tanks were included as replicates (N = 3), with two sub-replicate pots nested within aquaria. For net primary production, shoot and rhizome-root respiration, linear models were used for analysis, with aquaria as replicates (N = 3) and without nested sub-replicate pots. P-values < 0.05 are in bold.