MEPS 600:21-39 (2018)  -  DOI: https://doi.org/10.3354/meps12663

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 (C_IA) and phytoplankton (C_PP) 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 C_PP than C_IA 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 C_PP and C_IA found at either site. Overall, the total processing (i.e. assimilation and respiration) of C_PP was 33 and 37% higher than processing of C_IA 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.

KEY WORDS: Arctic · Carbon cycling · Sediment · Respiration · ¹³C · Bacteria · Benthic-pelagic coupling · Sea ice cover

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Cite this article as: Mäkelä A, Witte U, Archambault P (2018) Short-term processing of ice algal- and phytoplankton-derived carbon by Arctic benthic communities revealed through isotope labelling experiments. Mar Ecol Prog Ser 600:21-39. https://doi.org/10.3354/meps12663 Export citation Share:    Facebook - - linkedIn