Nitrogen cycling in the Barents Sea - seasonal dynamics of new and regenerated production in the marginal ice zone

• Main Authors: Kristiansen, Svein, Farbrot, Tove, Wheeler, Patricia A.
• Format: Article in Journal/Newspaper
• Language: English; unknown
• Published: American Society of Limnology and Oceanography
• Subjects: Barents Sea
• Online Access: https://ir.library.oregonstate.edu/concern/articles/vm40xt10c

The uptake rates of nitrate, ammonium, and urea were measured with a ¹⁵N technique during seven cruises in the marginal ice zone (MIZ) in the Barents Sea in 1984–1988. The results from all the cruises were pooled to obtain means for the prebloom, bloom, transition, and postbloom periods. New production—nitrate uptake as percent of total uptake—was high (92–96%) during the prebloom and bloom periods and decreased thereafter. Regenerated production—summed ammonium + urea uptake as percent of total uptake—increased through the bloom cycle and was at its maximum (75–93%) during the postbloom period. New production (as percent of the total) was higher in the ice‐filled parts than in the icefree parts, especially during the postbloom period. Nitrate uptake rates, however, were highest (9–25 nM h⁻¹) in open and ice‐free parts during the bloom and transition period. Mean growth rate of phytoplankton‐nitrogen was 0.5 doubling d⁻¹ during the bloom and ranged from 0.3 to 0.4 doubling d⁻¹ after the bloom. We hypothesize that primary production in the MIZ is not nutrient limited but is proportional to phytoplankton standing stocks.