The time‐course of uptake of inorganic and organic nitrogen compounds by phytoplankton from the Eastern Canadian Arctic: A comparison with temperate and tropical populations

• Published in: Limnology and Oceanography
• Main Author: Harrison, W. G.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1983
• Subjects: Aquatic Science; Oceanography; Arctic; Phytoplankton
• Online Access: http://dx.doi.org/10.4319/lo.1983.28.6.1231; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.4319%2Flo.1983.28.6.1231; https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.1983.28.6.1231

Uptake of inorganic (NO 3 ‒ , NH 4 + ) and organic (urea) nitrogen compounds by arctic phytoplankton was linear for at least 30 h of incubation under natural temperature and light conditions. Extrapolation of linear fits of the data showed positive ordinal intercepts for NH 4 + , suggesting relatively more rapid uptake early in the incubation period. Short term uptake experiments confirmed this; rates computed from 20‐min incubations were on the average 3‐fold higher than 24‐h uptake rates. The transient nature of these enhanced uptake rates resulted in their contributing little (<10%) to the total mass flux observed over 24 h. Comparison of these experiments with similar measurements from temperate and tropical waters suggests that the often observed nonlinearity in nitrogen uptake in the field may be more a consequence of isotope dilution and recycling than substrate exhaustion.