Respiration and bacterial carbon dynamics in the Amundsen Gulf, western Canadian Arctic

Respiration rates are fundamental to understanding ecosystem C flux; however, respiration remains poorly characterized in polar oceans. The Circumpolar Flaw Lead (CFL) study provided a unique opportunity to sample the Amundsen Gulf, from November 2007 to July 2008 and follow microbial C dynamics. Th...

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Bibliographic Details
Published in:Journal of Geophysical Research: Oceans 2012-09, Vol.117 (C9), p.n/a
Main Authors: Nguyen, Dan, Maranger, Roxane, Tremblay, Jean-Éric, Gosselin, Michel
Format: Article
Language:English
Subjects:
Arctic Ocean
Bacteria
bacterial production
Biological oceanography
C cycle
Chemical oceanography
Geophysics
Marine
Marine ecosystems
Oceanography
Oceans
Primary production
Respiration
Spring
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Summary:Respiration rates are fundamental to understanding ecosystem C flux; however, respiration remains poorly characterized in polar oceans. The Circumpolar Flaw Lead (CFL) study provided a unique opportunity to sample the Amundsen Gulf, from November 2007 to July 2008 and follow microbial C dynamics. This study shows that bacterial production (BP) was highly variable, ranging from 0.01 to 2.14 μg C L−1 d−1 (CV = 192%), whereas the range in community respiration (CR) was more conservative from 3.8 to 44.2 μg C L−1 d−1 (CV = 55%), with measurable rates throughout the year. The spring‐summer peak in BP preceded the peak in CR suggesting differential predominant control. From May until July, BP was more related to chlorophyll a concentration (r = 0.68) whereas CR was not. Given the observed high variability, BP was the main driver of bacterial growth efficiency (BGE) (r2 = 0.86). The overall average BGE was low at 4.6%, ranging from 0.20 in winter to a peak of 18.6% during the spring bloom. This study confirms that respiration is an important fate for C in the Amundsen Gulf, and our rate‐based estimates of ecosystem scale CR suggests that considerably more C is respired than could be accounted for by gross primary production (GPP). One of the most plausible explanations for this observed discrepancy is that regenerated primary production is currently underestimated. Key Points High respiration in Arctic waters Low bacterial growth efficiencies High respiration rates are likely supported by regenerated primary production
ISSN:0148-0227
2169-9275
2156-2202
2169-9291
DOI:10.1029/2011JC007343