Nitrogen uptake and growth rate of kelp (Laminaria saccharina) grown in an outdoor culture system using salmon culture effluent

Awal Subandar
Salmon netpen culture operation is going to grow in the next 5 years in British Columbia, and this culture generates nutrient loading. Kelp could utilize this nutrient to grow. To investigate the feasibility of an integrated culture of kelp and salmon, 3 consecutive experiments (each lasted 9 days) using kelp (Laminaria saccharina) (length 15 cm) were conducted at Marine Ecosystem Programme (West Vancouver) during April-September, 1990. The objectives were to test the effect of flow and kelp
more » ... of flow and kelp density on nitrogen removal, nitrogen uptake, growth, biomass and dissolved oxygen production of kelp. The flow treatment consisted of 3 levels (8.1-24, 25-44.1, 65.2-83.51 h⁻¹), and the density treatment consisted of 4 levels (0, 10, 15, 20 plants/tank or 0, 370, 555, 740 kelp/m³, respectively). The kelp were grown in 12 Plexiglas tanks (45x45x20 cm⁻³). Water samples of NH₄⁺ and NO₃⁻ (morning, afternoon), growth measurement and biomass harvesting were conducted every 3 days. Luxurious uptake of nitrogen was not evident because C/N ratio (10-11) was stable in all experiments. The treatments with kelp demonstrated higher total nitrogen removal than the controls (no kelp). The removal rate ranged 32.9-339 μmol l⁻¹ h⁻¹ (30-40%). The total nitrogen uptake rate ranged 6.1-22.5 μmol g⁻¹ dry mass h⁻¹. The high-flow, low-density tank had the highest total nitrogen uptake. The mean uptake based on 3 days growth for all flow-density combinations were similar. The range of mean uptake based on 3 days growth was 5.4-8.3 μmol g⁻¹ dry mass h⁻¹. The kelp utilized NH₄⁺ and NO₃⁻ equally. No differences of total nitrogen (NH₄⁺ and NO₃⁻), NH₄⁺ and NO₃⁻ uptake values were evident between morning and afternoon sampling time for all flow-density combinations. The growth ranged between 6.5-9 % d⁻¹. The biomass production ranged from 1.3-2.1 g per sampling. The highest growth rate and biomass production was performed by kelp in the high-flow, low-density tank. The biomass production appeared to increase as nitrogen uptake increased. Intraspecifi [...]
doi:10.14288/1.0058813 fatcat:albg6hlwa5aizl2hctrbxputoq