Table 1.
Cellular characteristics of N. oceanica and Phaeodactylum tricornutum
| Species | P. tricornutum | N. oceanica | ||||||
|---|---|---|---|---|---|---|---|---|
| Treatment | N+ | N− | A | A+W | N+ | N− | A | A+W |
| Cell abundance (×106 cells mL−1) | 20.4 | 6.25 | 11 | 10 | 48.1 | 24.5 | 5.64 | 36.1 |
| µmax (day−1) | 0.35 (± 0.02) | 0.21(a) (± 0.02) | 0.29 (± 0.03) | 0.29 (± 0.02) | 0.42 (± 0.01) | 0.29(a) (± 0.03) | 0.38(b) (± 0.03) | 0.36(b) (± 0.02) |
| POC (µg mg−1) | 328.4 (± 21.7) | 310.6 (± 24.2) | 345.5 (± 32.1) | 288.9 (± 7.9) | 503.2 (± 7.9) | 590.1(a) (± 8.8) | 576.2(a) (± 1.0) | 534.8 (± 18.6) |
| PON (µg mg−1) | 32.8 (± 1.6) | 20.3(a) (± 0.9) | 28.5(b) (± 1.0) | 26.5(a, b) (± 1.0) | 48.4 (± 0.6) | 23.0(a) (± 1.0) | 43.1(b) (± 0.6) | 45.2(b) (± 2.2) |
Maximum growth rate (µmax), cell abundance, particulate organic carbon (POC) and particulate organic nitrogen (PON) are compared for the two species in the four conditions tested [nitrate (N+), nitrogen free (N−), ammonium (A) and ammonium with tungstate (A+W) conditions]. Mean (± standard error) values are given. Analysis of the variance followed by Bonferroni post hoc test (p value < 0.05) was carried out to estimate the significance of the differences between treatments, being (a) significant difference when comparing to the N+ treatment, (b) significant difference when comparing to the N− treatment