Sinking krill carcasses as hotspots of microbial carbon and nitrogen cycling in the Arctic
Krill represent a major link between primary producers and higher trophic levels in polar marine food webs. Potential links to lower trophic levels, such as heterotrophic microorganisms, are less well documented. Here, we studied the kinetics of microbial degradation of sinking carcasses of two domi...
Published in: | Frontiers in Marine Science |
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Main Authors: | , , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
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2022
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Online Access: | https://orbit.dtu.dk/en/publications/275abb6a-3516-4713-bdc7-720f4e0e3072 https://doi.org/10.3389/fmars.2022.1019727 https://backend.orbit.dtu.dk/ws/files/297199695/fmars_09_1019727.pdf |
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ftdtupubl:oai:pure.atira.dk:publications/275abb6a-3516-4713-bdc7-720f4e0e3072 2024-09-15T17:51:07+00:00 Sinking krill carcasses as hotspots of microbial carbon and nitrogen cycling in the Arctic Franco-Cisterna, Belén Glud, Anni Bristow, Laura A. Rudra, Arka Sanei, Hamed Winding, Mie H.S. Nielsen, Torkel G. Glud, Ronnie N. Stief, Peter 2022 application/pdf https://orbit.dtu.dk/en/publications/275abb6a-3516-4713-bdc7-720f4e0e3072 https://doi.org/10.3389/fmars.2022.1019727 https://backend.orbit.dtu.dk/ws/files/297199695/fmars_09_1019727.pdf eng eng https://orbit.dtu.dk/en/publications/275abb6a-3516-4713-bdc7-720f4e0e3072 info:eu-repo/semantics/openAccess Franco-Cisterna , B , Glud , A , Bristow , L A , Rudra , A , Sanei , H , Winding , M H S , Nielsen , T G , Glud , R N & Stief , P 2022 , ' Sinking krill carcasses as hotspots of microbial carbon and nitrogen cycling in the Arctic ' , Frontiers in Marine Science , vol. 9 , 1019727 . https://doi.org/10.3389/fmars.2022.1019727 Biological carbon pump Marine snow Nitrogen Carbon Oxygen Krill Degradation Mineralization /dk/atira/pure/sustainabledevelopmentgoals/life_below_water name=SDG 14 - Life Below Water article 2022 ftdtupubl https://doi.org/10.3389/fmars.2022.1019727 2024-07-29T23:50:18Z Krill represent a major link between primary producers and higher trophic levels in polar marine food webs. Potential links to lower trophic levels, such as heterotrophic microorganisms, are less well documented. Here, we studied the kinetics of microbial degradation of sinking carcasses of two dominant krill species Thysanoessa raschii and Meganyctiphanes norvegica from Southwest Greenland. Degradation experiments under oxic conditions showed that 6.0-9.1% of carbon and 6.4-7.1% of nitrogen were lost from the carcasses after one week. Aerobic microbial respiration and the release of dissolved organic carbon were the main pathways of carbon loss from the carcasses. Ammonium release generally contributed the most to carcass nitrogen loss. Oxygen micro profiling revealed anoxic conditions inside krill carcasses/specimens, allowing anaerobic nitrogen cycling through denitrification and dissimilatory nitrate reduction to ammonium (DNRA). Denitrification rates were up to 5.3 and 127.7 nmol N carcass -1 d -1 for T. raschii and M. norvegica , respectively, making krill carcasses hotspots of nitrogen loss in the oxygenated water column of the fjord. Carcass-associated DNRA rates were up to 4-fold higher than denitrification rates, but the combined activity of these two anaerobic respiration processes did not contribute significantly to carbon loss from the carcasses. Living krill specimens did not harbor any significant denitrification and DNRA activity despite having an anoxic gut as revealed by micro profiling. The investigated krill carcasses sink fast (1500-3000 m d -1 ) and our data show that only a small fraction of the associated carbon is lost during descent. Based on data on krill distribution, our findings are used to discuss the potential importance of sinking krill carcasses for sustaining benthic food webs in the Arctic. Article in Journal/Newspaper Arctic Greenland Meganyctiphanes norvegica Thysanoessa raschii Technical University of Denmark: DTU Orbit Frontiers in Marine Science 9 |
institution |
Open Polar |
collection |
Technical University of Denmark: DTU Orbit |
op_collection_id |
ftdtupubl |
language |
English |
topic |
Biological carbon pump Marine snow Nitrogen Carbon Oxygen Krill Degradation Mineralization /dk/atira/pure/sustainabledevelopmentgoals/life_below_water name=SDG 14 - Life Below Water |
spellingShingle |
Biological carbon pump Marine snow Nitrogen Carbon Oxygen Krill Degradation Mineralization /dk/atira/pure/sustainabledevelopmentgoals/life_below_water name=SDG 14 - Life Below Water Franco-Cisterna, Belén Glud, Anni Bristow, Laura A. Rudra, Arka Sanei, Hamed Winding, Mie H.S. Nielsen, Torkel G. Glud, Ronnie N. Stief, Peter Sinking krill carcasses as hotspots of microbial carbon and nitrogen cycling in the Arctic |
topic_facet |
Biological carbon pump Marine snow Nitrogen Carbon Oxygen Krill Degradation Mineralization /dk/atira/pure/sustainabledevelopmentgoals/life_below_water name=SDG 14 - Life Below Water |
description |
Krill represent a major link between primary producers and higher trophic levels in polar marine food webs. Potential links to lower trophic levels, such as heterotrophic microorganisms, are less well documented. Here, we studied the kinetics of microbial degradation of sinking carcasses of two dominant krill species Thysanoessa raschii and Meganyctiphanes norvegica from Southwest Greenland. Degradation experiments under oxic conditions showed that 6.0-9.1% of carbon and 6.4-7.1% of nitrogen were lost from the carcasses after one week. Aerobic microbial respiration and the release of dissolved organic carbon were the main pathways of carbon loss from the carcasses. Ammonium release generally contributed the most to carcass nitrogen loss. Oxygen micro profiling revealed anoxic conditions inside krill carcasses/specimens, allowing anaerobic nitrogen cycling through denitrification and dissimilatory nitrate reduction to ammonium (DNRA). Denitrification rates were up to 5.3 and 127.7 nmol N carcass -1 d -1 for T. raschii and M. norvegica , respectively, making krill carcasses hotspots of nitrogen loss in the oxygenated water column of the fjord. Carcass-associated DNRA rates were up to 4-fold higher than denitrification rates, but the combined activity of these two anaerobic respiration processes did not contribute significantly to carbon loss from the carcasses. Living krill specimens did not harbor any significant denitrification and DNRA activity despite having an anoxic gut as revealed by micro profiling. The investigated krill carcasses sink fast (1500-3000 m d -1 ) and our data show that only a small fraction of the associated carbon is lost during descent. Based on data on krill distribution, our findings are used to discuss the potential importance of sinking krill carcasses for sustaining benthic food webs in the Arctic. |
format |
Article in Journal/Newspaper |
author |
Franco-Cisterna, Belén Glud, Anni Bristow, Laura A. Rudra, Arka Sanei, Hamed Winding, Mie H.S. Nielsen, Torkel G. Glud, Ronnie N. Stief, Peter |
author_facet |
Franco-Cisterna, Belén Glud, Anni Bristow, Laura A. Rudra, Arka Sanei, Hamed Winding, Mie H.S. Nielsen, Torkel G. Glud, Ronnie N. Stief, Peter |
author_sort |
Franco-Cisterna, Belén |
title |
Sinking krill carcasses as hotspots of microbial carbon and nitrogen cycling in the Arctic |
title_short |
Sinking krill carcasses as hotspots of microbial carbon and nitrogen cycling in the Arctic |
title_full |
Sinking krill carcasses as hotspots of microbial carbon and nitrogen cycling in the Arctic |
title_fullStr |
Sinking krill carcasses as hotspots of microbial carbon and nitrogen cycling in the Arctic |
title_full_unstemmed |
Sinking krill carcasses as hotspots of microbial carbon and nitrogen cycling in the Arctic |
title_sort |
sinking krill carcasses as hotspots of microbial carbon and nitrogen cycling in the arctic |
publishDate |
2022 |
url |
https://orbit.dtu.dk/en/publications/275abb6a-3516-4713-bdc7-720f4e0e3072 https://doi.org/10.3389/fmars.2022.1019727 https://backend.orbit.dtu.dk/ws/files/297199695/fmars_09_1019727.pdf |
genre |
Arctic Greenland Meganyctiphanes norvegica Thysanoessa raschii |
genre_facet |
Arctic Greenland Meganyctiphanes norvegica Thysanoessa raschii |
op_source |
Franco-Cisterna , B , Glud , A , Bristow , L A , Rudra , A , Sanei , H , Winding , M H S , Nielsen , T G , Glud , R N & Stief , P 2022 , ' Sinking krill carcasses as hotspots of microbial carbon and nitrogen cycling in the Arctic ' , Frontiers in Marine Science , vol. 9 , 1019727 . https://doi.org/10.3389/fmars.2022.1019727 |
op_relation |
https://orbit.dtu.dk/en/publications/275abb6a-3516-4713-bdc7-720f4e0e3072 |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.3389/fmars.2022.1019727 |
container_title |
Frontiers in Marine Science |
container_volume |
9 |
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1810292923596537856 |