Short-term processing of ice algal- and phytoplankton-derived carbon by Arctic benthic communities revealed through isotope labelling experiments

Anni Mäkelä, Ursula Witte, Philippe Archambault

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Abstract

Benthic ecosystems play a significant role in the carbon (C) cycle through remineralization of organic matter reaching the seafloor. Ice algae and phytoplankton are major C sources for Arctic benthic consumers, but climate change-mediated loss of summer sea ice is predicted to change Arctic marine primary production by increasing phytoplankton and reducing ice algal contributions. To investigate the impact of changing algal C sources on benthic C processing, 2 isotope tracing experiments on 13C-labelled ice algae and phytoplankton were conducted in the North Water Polynya (NOW; 709 m depth) and Lancaster Sound (LS; 794 m) in the Canadian Arctic, during which the fate of ice algal (CIA) and phytoplankton (CPP) C added to sediment cores was traced over 4 d. No difference in sediment community oxygen consumption (SCOC, indicative of total C turnover) between the background measurements and ice algal or phytoplankton cores was found at either site. Most of the processed algal C was respired, with significantly more CPP than CIA being released as dissolved inorganic C at both sites. Macroinfaunal uptake of algal C was minor, but bacterial assimilation accounted for 33-44% of total algal C processing, with no differences in bacterial uptake of CPP and CIA found at either site. Overall, the total processing (i.e. assimilation and respiration) of CPP was 33 and 37% higher than processing of CIA in NOW and in LS, respectively, suggesting that the future changes in quality of organic matter sinking to the seafloor could impact the C residence time at the seafloor.
Original languageEnglish
Pages (from-to)21-39
Number of pages19
JournalMarine Ecology Progress Series
Volume600
Early online date30 Jul 2018
DOIs
Publication statusPublished - 2018

Fingerprint

isotope labeling
benthos
Arctic region
ice
phytoplankton
isotope
carbon
algae
experiment
ice alga
seafloor
assimilation (physiology)
organic matter
uptake mechanisms
polynya
sediments
remineralization
labelling
oxygen consumption
cell respiration

Keywords

  • Arctic
  • carbon cycling
  • sediment
  • respiration
  • 13C
  • bacteria
  • Benthic-pelagic coupling
  • sea ice cover

Cite this

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title = "Short-term processing of ice algal- and phytoplankton-derived carbon by Arctic benthic communities revealed through isotope labelling experiments",
abstract = "Benthic ecosystems play a significant role in the carbon (C) cycle through remineralization of organic matter reaching the seafloor. Ice algae and phytoplankton are major C sources for Arctic benthic consumers, but climate change-mediated loss of summer sea ice is predicted to change Arctic marine primary production by increasing phytoplankton and reducing ice algal contributions. To investigate the impact of changing algal C sources on benthic C processing, 2 isotope tracing experiments on 13C-labelled ice algae and phytoplankton were conducted in the North Water Polynya (NOW; 709 m depth) and Lancaster Sound (LS; 794 m) in the Canadian Arctic, during which the fate of ice algal (CIA) and phytoplankton (CPP) C added to sediment cores was traced over 4 d. No difference in sediment community oxygen consumption (SCOC, indicative of total C turnover) between the background measurements and ice algal or phytoplankton cores was found at either site. Most of the processed algal C was respired, with significantly more CPP than CIA being released as dissolved inorganic C at both sites. Macroinfaunal uptake of algal C was minor, but bacterial assimilation accounted for 33-44{\%} of total algal C processing, with no differences in bacterial uptake of CPP and CIA found at either site. Overall, the total processing (i.e. assimilation and respiration) of CPP was 33 and 37{\%} higher than processing of CIA in NOW and in LS, respectively, suggesting that the future changes in quality of organic matter sinking to the seafloor could impact the C residence time at the seafloor.",
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author = "Anni M{\"a}kel{\"a} and Ursula Witte and Philippe Archambault",
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T1 - Short-term processing of ice algal- and phytoplankton-derived carbon by Arctic benthic communities revealed through isotope labelling experiments

AU - Mäkelä, Anni

AU - Witte, Ursula

AU - Archambault, Philippe

PY - 2018

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N2 - Benthic ecosystems play a significant role in the carbon (C) cycle through remineralization of organic matter reaching the seafloor. Ice algae and phytoplankton are major C sources for Arctic benthic consumers, but climate change-mediated loss of summer sea ice is predicted to change Arctic marine primary production by increasing phytoplankton and reducing ice algal contributions. To investigate the impact of changing algal C sources on benthic C processing, 2 isotope tracing experiments on 13C-labelled ice algae and phytoplankton were conducted in the North Water Polynya (NOW; 709 m depth) and Lancaster Sound (LS; 794 m) in the Canadian Arctic, during which the fate of ice algal (CIA) and phytoplankton (CPP) C added to sediment cores was traced over 4 d. No difference in sediment community oxygen consumption (SCOC, indicative of total C turnover) between the background measurements and ice algal or phytoplankton cores was found at either site. Most of the processed algal C was respired, with significantly more CPP than CIA being released as dissolved inorganic C at both sites. Macroinfaunal uptake of algal C was minor, but bacterial assimilation accounted for 33-44% of total algal C processing, with no differences in bacterial uptake of CPP and CIA found at either site. Overall, the total processing (i.e. assimilation and respiration) of CPP was 33 and 37% higher than processing of CIA in NOW and in LS, respectively, suggesting that the future changes in quality of organic matter sinking to the seafloor could impact the C residence time at the seafloor.

AB - Benthic ecosystems play a significant role in the carbon (C) cycle through remineralization of organic matter reaching the seafloor. Ice algae and phytoplankton are major C sources for Arctic benthic consumers, but climate change-mediated loss of summer sea ice is predicted to change Arctic marine primary production by increasing phytoplankton and reducing ice algal contributions. To investigate the impact of changing algal C sources on benthic C processing, 2 isotope tracing experiments on 13C-labelled ice algae and phytoplankton were conducted in the North Water Polynya (NOW; 709 m depth) and Lancaster Sound (LS; 794 m) in the Canadian Arctic, during which the fate of ice algal (CIA) and phytoplankton (CPP) C added to sediment cores was traced over 4 d. No difference in sediment community oxygen consumption (SCOC, indicative of total C turnover) between the background measurements and ice algal or phytoplankton cores was found at either site. Most of the processed algal C was respired, with significantly more CPP than CIA being released as dissolved inorganic C at both sites. Macroinfaunal uptake of algal C was minor, but bacterial assimilation accounted for 33-44% of total algal C processing, with no differences in bacterial uptake of CPP and CIA found at either site. Overall, the total processing (i.e. assimilation and respiration) of CPP was 33 and 37% higher than processing of CIA in NOW and in LS, respectively, suggesting that the future changes in quality of organic matter sinking to the seafloor could impact the C residence time at the seafloor.

KW - Arctic

KW - carbon cycling

KW - sediment

KW - respiration

KW - 13C

KW - bacteria

KW - Benthic-pelagic coupling

KW - sea ice cover

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SP - 21

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JO - Marine Ecology Progress Series

JF - Marine Ecology Progress Series

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