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 language | English |
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Pages (from-to) | 21-39 |
Number of pages | 19 |
Journal | Marine Ecology Progress Series |
Volume | 600 |
Early online date | 30 Jul 2018 |
DOIs | |
Publication status | Published - 2018 |
Keywords
- Arctic
- carbon cycling
- sediment
- respiration
- 13C
- bacteria
- Benthic-pelagic coupling
- sea ice cover