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 |
---|---|
Main Authors: | , , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
2022
|
Subjects: | |
Online Access: | https://portal.findresearcher.sdu.dk/da/publications/bebb96ea-94d9-472c-a771-bda4a8b22140 https://doi.org/10.3389/fmars.2022.1019727 https://findresearcher.sdu.dk/ws/files/213816202/fmars_09_1019727.pdf |
id |
ftsydanskunivpub:oai:sdu.dk:publications/bebb96ea-94d9-472c-a771-bda4a8b22140 |
---|---|
record_format |
openpolar |
spelling |
ftsydanskunivpub:oai:sdu.dk:publications/bebb96ea-94d9-472c-a771-bda4a8b22140 2024-09-15T17:51:08+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 2022-11-03 application/pdf https://portal.findresearcher.sdu.dk/da/publications/bebb96ea-94d9-472c-a771-bda4a8b22140 https://doi.org/10.3389/fmars.2022.1019727 https://findresearcher.sdu.dk/ws/files/213816202/fmars_09_1019727.pdf eng eng https://portal.findresearcher.sdu.dk/da/publications/bebb96ea-94d9-472c-a771-bda4a8b22140 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 carbon degradation krill marine snow mineralization nitrogen oxygen article 2022 ftsydanskunivpub https://doi.org/10.3389/fmars.2022.1019727 2024-08-05T23:48:16Z 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. 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 ... Article in Journal/Newspaper Arctic Arctic krill Greenland Meganyctiphanes norvegica Thysanoessa raschii University of Southern Denmark Research Portal Frontiers in Marine Science 9 |
institution |
Open Polar |
collection |
University of Southern Denmark Research Portal |
op_collection_id |
ftsydanskunivpub |
language |
English |
topic |
Biological carbon pump carbon degradation krill marine snow mineralization nitrogen oxygen |
spellingShingle |
Biological carbon pump carbon degradation krill marine snow mineralization nitrogen oxygen 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 carbon degradation krill marine snow mineralization nitrogen oxygen |
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. 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 ... |
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://portal.findresearcher.sdu.dk/da/publications/bebb96ea-94d9-472c-a771-bda4a8b22140 https://doi.org/10.3389/fmars.2022.1019727 https://findresearcher.sdu.dk/ws/files/213816202/fmars_09_1019727.pdf |
genre |
Arctic Arctic krill Greenland Meganyctiphanes norvegica Thysanoessa raschii |
genre_facet |
Arctic Arctic krill 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://portal.findresearcher.sdu.dk/da/publications/bebb96ea-94d9-472c-a771-bda4a8b22140 |
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 |
_version_ |
1810292953615171584 |