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The transformation and fate of sub‐Arctic microphytobenthos carbon revealed through 13 C‐labeling
Author(s) -
Oakes Joanne M.,
Rysgaard Søren,
Glud Ronnie N.,
Eyre Bradley D.
Publication year - 2016
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.1002/lno.10377
Subject(s) - arctic , sediment , δ13c , latitude , total organic carbon , temperate climate , carbon cycle , carbon fibers , oceanography , environmental science , environmental chemistry , isotopes of carbon , ecology , geology , chemistry , biology , stable isotope ratio , paleontology , ecosystem , physics , materials science , composite number , composite material , geodesy , quantum mechanics
Microphytobenthos (MPB) at higher latitudes has been poorly studied. This study used pulse‐chase 13 C‐labeling to investigate the production, processing, and fate of MPB‐derived carbon (MPB‐C) in sub‐Arctic intertidal sediments over 31 d. Gross primary production (2.1 mmol C m −2 h −1 ± 0.4 mmol C m −2 h −1 ) was comparable to that reported for temperate regions. Some of the 13 C fixed by sub‐Arctic MPB was rapidly (within 0.5 d) transferred to deeper sediments (below 2 cm), but most was retained within surface sediments (>70.2% of the 13 C present at any time during the study). At any time, MPB accounted for ≥ 49.8% of this 13 C. The 13 C content of sediment organic carbon declined over time, but > 31% of the 13 C fixed within the first tidal cycle remained after 31 d, suggesting that sub‐Arctic MPB may contribute to coastal carbon retention during the productive season. Over 21 d, 10.6% of the fixed 13 C was removed via DIC fluxes and 0.3% via DOC fluxes from inundated sediment, and 0.6% as CO 2 from exposed sediment. The greatest loss of 13 C (38.2%) was via unmeasured pathways, including resuspension and/or removal by mobile consumers. The rates of MPB‐C production and the relative importance of the pathways for MPB‐C loss were similar to that observed for comparable lower latitude sediments, demonstrating that MPB at higher latitudes are not necessarily distinct from MPB at lower latitudes and probably play a similarly important role in ecosystem functioning. Apparently, local environmental conditions are more important than climate differences for determining the processing and fate of MPB‐C.