Copepod carcasses as microbial hot spots for pelagic denitrification

Copepods are exposed to a high non-predatory mortality and their decomposing carcasses act as microniches with intensified microbial activity. Sinking carcasses could thereby represent anoxic microenvironment sustaining anaerobic microbial pathways in otherwise oxic water columns. Using non-invasive...

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Published in:Limnology and Oceanography
Main Authors: Glud, RN, Grossart, HP, Larsen, M, Tang, KW, Arendt, KE
Format: Text
Language:unknown
Published: W&M ScholarWorks 2015
Subjects:
Online Access:https://scholarworks.wm.edu/vimsarticles/824
https://scholarworks.wm.edu/context/vimsarticles/article/1824/viewcontent/lno.10149.pdf
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spelling ftwilliammarycol:oai:scholarworks.wm.edu:vimsarticles-1824 2023-06-11T04:10:45+02:00 Copepod carcasses as microbial hot spots for pelagic denitrification Glud, RN Grossart, HP Larsen, M Tang, KW Arendt, KE 2015-01-01T08:00:00Z application/pdf https://scholarworks.wm.edu/vimsarticles/824 doi: 10.1002/lno.10149 https://scholarworks.wm.edu/context/vimsarticles/article/1824/viewcontent/lno.10149.pdf unknown W&M ScholarWorks https://scholarworks.wm.edu/vimsarticles/824 doi: 10.1002/lno.10149 https://scholarworks.wm.edu/context/vimsarticles/article/1824/viewcontent/lno.10149.pdf VIMS Articles Fecal Pellets Marine-Sediments N-2 Production Arabian Sea Fresh-Water Zooplankton Bacteria Mortality Greenland Anammox Biological Sciences Peer-Reviewed Articles Aquaculture and Fisheries text 2015 ftwilliammarycol https://doi.org/10.1002/lno.10149 2023-05-04T17:43:31Z Copepods are exposed to a high non-predatory mortality and their decomposing carcasses act as microniches with intensified microbial activity. Sinking carcasses could thereby represent anoxic microenvironment sustaining anaerobic microbial pathways in otherwise oxic water columns. Using non-invasive O-2 imaging, we document that carcasses of Calanus finmarchicus had an anoxic interior even at fully air-saturated ambient O-2 level. The extent of anoxia gradually expanded with decreasing ambient O-2 levels. Concurrent microbial sampling showed the expression of nitrite reductase genes (nirS) in all investigated carcass samples and thereby documented the potential for microbial denitrification in carcasses. The nirS gene was occasionally expressed in live copepods, but not as consistently as in carcasses. Incubations of sinking carcasses in (15)NO3-amended seawater demonstrated denitrification, of which on average 34%+/- 17% (n=28) was sustained by nitrification. However, the activity was highly variable and was strongly dependent on the ambient O-2 levels. While denitrification was present even at air-saturation (302 mol L-1), the average carcass specific activity increased several orders of magnitude to approximate to 1 nmol d(-1) at 20% air-saturation (55 mol O-2 L-1) at an ambient temperature of 7 degrees C. Sinking carcasses of C. finmarchicus therefore represent hotspots of pelagic denitrification, but the quantitative importance as a sink for bioavailable nitrogen is strongly dependent on the ambient O-2 level. The importance of carcass associated denitrification could be highly significant in O-2 depleted environments such as Oxygen Minimum Zones (OMZ). Text Calanus finmarchicus Greenland Copepods W&M ScholarWorks Greenland Limnology and Oceanography 60 6 2026 2036
institution Open Polar
collection W&M ScholarWorks
op_collection_id ftwilliammarycol
language unknown
topic Fecal Pellets
Marine-Sediments
N-2 Production
Arabian Sea
Fresh-Water
Zooplankton
Bacteria
Mortality
Greenland
Anammox
Biological Sciences Peer-Reviewed Articles
Aquaculture and Fisheries
spellingShingle Fecal Pellets
Marine-Sediments
N-2 Production
Arabian Sea
Fresh-Water
Zooplankton
Bacteria
Mortality
Greenland
Anammox
Biological Sciences Peer-Reviewed Articles
Aquaculture and Fisheries
Glud, RN
Grossart, HP
Larsen, M
Tang, KW
Arendt, KE
Copepod carcasses as microbial hot spots for pelagic denitrification
topic_facet Fecal Pellets
Marine-Sediments
N-2 Production
Arabian Sea
Fresh-Water
Zooplankton
Bacteria
Mortality
Greenland
Anammox
Biological Sciences Peer-Reviewed Articles
Aquaculture and Fisheries
description Copepods are exposed to a high non-predatory mortality and their decomposing carcasses act as microniches with intensified microbial activity. Sinking carcasses could thereby represent anoxic microenvironment sustaining anaerobic microbial pathways in otherwise oxic water columns. Using non-invasive O-2 imaging, we document that carcasses of Calanus finmarchicus had an anoxic interior even at fully air-saturated ambient O-2 level. The extent of anoxia gradually expanded with decreasing ambient O-2 levels. Concurrent microbial sampling showed the expression of nitrite reductase genes (nirS) in all investigated carcass samples and thereby documented the potential for microbial denitrification in carcasses. The nirS gene was occasionally expressed in live copepods, but not as consistently as in carcasses. Incubations of sinking carcasses in (15)NO3-amended seawater demonstrated denitrification, of which on average 34%+/- 17% (n=28) was sustained by nitrification. However, the activity was highly variable and was strongly dependent on the ambient O-2 levels. While denitrification was present even at air-saturation (302 mol L-1), the average carcass specific activity increased several orders of magnitude to approximate to 1 nmol d(-1) at 20% air-saturation (55 mol O-2 L-1) at an ambient temperature of 7 degrees C. Sinking carcasses of C. finmarchicus therefore represent hotspots of pelagic denitrification, but the quantitative importance as a sink for bioavailable nitrogen is strongly dependent on the ambient O-2 level. The importance of carcass associated denitrification could be highly significant in O-2 depleted environments such as Oxygen Minimum Zones (OMZ).
format Text
author Glud, RN
Grossart, HP
Larsen, M
Tang, KW
Arendt, KE
author_facet Glud, RN
Grossart, HP
Larsen, M
Tang, KW
Arendt, KE
author_sort Glud, RN
title Copepod carcasses as microbial hot spots for pelagic denitrification
title_short Copepod carcasses as microbial hot spots for pelagic denitrification
title_full Copepod carcasses as microbial hot spots for pelagic denitrification
title_fullStr Copepod carcasses as microbial hot spots for pelagic denitrification
title_full_unstemmed Copepod carcasses as microbial hot spots for pelagic denitrification
title_sort copepod carcasses as microbial hot spots for pelagic denitrification
publisher W&M ScholarWorks
publishDate 2015
url https://scholarworks.wm.edu/vimsarticles/824
https://scholarworks.wm.edu/context/vimsarticles/article/1824/viewcontent/lno.10149.pdf
geographic Greenland
geographic_facet Greenland
genre Calanus finmarchicus
Greenland
Copepods
genre_facet Calanus finmarchicus
Greenland
Copepods
op_source VIMS Articles
op_relation https://scholarworks.wm.edu/vimsarticles/824
doi: 10.1002/lno.10149
https://scholarworks.wm.edu/context/vimsarticles/article/1824/viewcontent/lno.10149.pdf
op_doi https://doi.org/10.1002/lno.10149
container_title Limnology and Oceanography
container_volume 60
container_issue 6
container_start_page 2026
op_container_end_page 2036
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