Table 1. The median (± S.E.) balanced growth rates and mean elemental stoichiometry and N2 fixation rates for T. erythraeum IMS101 when acclimated to three N-source conditions (N2, NH4+ and NO3-), at a target CO2 concentration (380 μatm), saturating light intensity (400 μmol photons m-2 s-1) and optimal temperature (26 °C).
| Variables | Units | N2 | NH4+ | NO3- |
|---|---|---|---|---|
| Growth rate | d-1 | 0.340 (0.038)[A] | 0.375 (0.011)[B] | 0.384 (0.005)[B] |
| Elemental Stoichiometry | ||||
| C:N | mol:mol | 6.9 (0.7) | 4.4 (0.9) | 3.9 (0.7) |
| C:P | mol:mol | 122.6 (7.0)[B] | 47.9 (2.4)[A] | 36.9 (2.9)[A] |
| N:P | mol:mol | 18.1 (1.3)[B] | 11.8 (2.2) | 9.9 (1.0)[A] |
| Chla:C | mg:mol | 134 (8)[A] | 239 (4)[B] | 222 (2)[B] |
| Chla:N | mg:mol | 906 (43) | 1041 (209) | 855 (154) |
| N2 Fixation | ||||
| Chla-specific | μmol N (mg Chla)-1 h-1 | 14.75 (1.66)[B] | 2.35 (0.49)[A] | 2.84 (0.44)[A] |
| C-specific | μmol N (mg C)-1 h-1 | 0.16 (0.01)[B] | 0.04 (0.01)[A] | 0.05 (0.01)[A] |
Abbreviations; C:N, C:P and N:P ratios are mol:mol, Chla:C and Chla:N ratios are mg:mol (n = 3). Letters in parenthesis indicate significant differences between N-source treatments (One Way ANOVA, Tukey post hoc test; P < .05); where [B] is significantly greater than [A].