Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Volume 15, issue 18
Biogeosciences, 15, 5503-5517, 2018
https://doi.org/10.5194/bg-15-5503-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Biogeosciences, 15, 5503-5517, 2018
https://doi.org/10.5194/bg-15-5503-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 17 Sep 2018

Research article | 17 Sep 2018

First in situ estimations of small phytoplankton carbon and nitrogen uptake rates in the Kara, Laptev, and East Siberian seas

P. Sadanandan Bhavya1, Jang Han Lee1, Ho Won Lee1, Jae Joong Kang1, Jae Hyung Lee1, Dabin Lee1, So Hyun An1, Dean A. Stockwell2, Terry E. Whitledge2, and Sang Heon Lee1 P. Sadanandan Bhavya et al.
  • 1Department of Oceanography, Pusan National University, Busan 609-735, Korea
  • 2Institute of Marine Science, University of Alaska, Fairbanks, AK 99775, USA

Abstract. Carbon and nitrogen uptake rates by small phytoplankton (0.7–5µm) in the Kara, Laptev, and East Siberian seas in the Arctic Ocean were quantified using in situ isotope labeling experiments; this research, which was novel and part of the NABOS (Nansen and Amundsen Basins Observational System) program, took place from 21 August to 22 September 2013. The depth-integrated carbon (C), nitrate (NO3), and ammonium (NH4+) uptake rates by small phytoplankton ranged from 0.54 to 15.96mgCm−2h−1, 0.05 to 1.02mgCm−2h−1, and 0.11 to 3.73mgNm−2h−1, respectively. The contributions of small phytoplankton towards the total C, NO3, and NH4+ varied from 25% to 89%, 31% to 89%, and 28% to 91%, respectively. The turnover times for NO3 and NH4+ by small phytoplankton found in the present study indicate the longer residence times (years) of the nutrients in the deeper waters, particularly for NO3. Additionally, the relatively higher C and N uptake rates by small phytoplankton obtained in the present study from locations with less sea ice concentration indicate the possibility that small phytoplankton thrive under the retreat of sea ice as a result of warming conditions. The high contributions of small phytoplankton to the total C and N uptake rates suggest the capability of small autotrophs to withstand the adverse hydrographic conditions introduced by climate change.

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