Table 1. Results from the ¹⁵NH₄ ⁺ addition experiment.

Treatment	Total Production μg N g−1 DW d−1	Net production μg N g−1DW d−1	Consumption μg N g−1DW d−1	Nitrification ng N g−1 DW d−1
L. pertusa white 1 μM	6.9 ± 1.1	5.7 ± 1.1	1.2 ± 0.1	14.6 ± 15.7
L. pertusa white 3 μM	5.0 ± 0.2	4.1 ± 0.1	0.9 ± 0.3	5.9 ± 1.4
L. pertusa red 1 μM	6.0 ± 2.0	5.2 ± 1.8	0.8 ± 0.5	3.0 ± 4.8
L. pertusa red 3 μM	2.4 ± 0.5	2.3 ± 0.3	0.7 ± 0.6	1.4 ± 2.4

Total and net ammonium production, total consumption and nitrification by red and white L. pertusa from Trondheim fjord. All data are the average ± SD and were obtained after an addition of 1 or 3 μM NH₄ ⁺ and incubation during two days. Note that nitrification rates are expressed in ng rather than μg N.