Hidden biosphere in an oxygen-deficient Atlantic open-ocean eddy: future implications of ocean deoxygenation on primary production in the eastern tropical North Atlantic
The eastern tropical North Atlantic (ETNA) is characterized by a highly productive coastal upwelling system and a moderate oxygen minimum zone with lowest open-ocean oxygen (O 2 ) concentrations of approximately 40 μmol kg −1 . The recent discovery of re-occurring mesoscale eddies with close to anox...
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ftdoajarticles:oai:doaj.org/article:1c2c5953f7bf4f268c8973e1fc43f226 2023-05-15T17:31:42+02:00 Hidden biosphere in an oxygen-deficient Atlantic open-ocean eddy: future implications of ocean deoxygenation on primary production in the eastern tropical North Atlantic C. R. Löscher M. A. Fischer S. C. Neulinger B. Fiedler M. Philippi F. Schütte A. Singh H. Hauss J. Karstensen A. Körtzinger S. Künzel R. A. Schmitz 2015-12-01T00:00:00Z https://doi.org/10.5194/bg-12-7467-2015 https://doaj.org/article/1c2c5953f7bf4f268c8973e1fc43f226 EN eng Copernicus Publications http://www.biogeosciences.net/12/7467/2015/bg-12-7467-2015.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 1726-4170 1726-4189 doi:10.5194/bg-12-7467-2015 https://doaj.org/article/1c2c5953f7bf4f268c8973e1fc43f226 Biogeosciences, Vol 12, Iss 24, Pp 7467-7482 (2015) Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 article 2015 ftdoajarticles https://doi.org/10.5194/bg-12-7467-2015 2022-12-31T16:13:51Z The eastern tropical North Atlantic (ETNA) is characterized by a highly productive coastal upwelling system and a moderate oxygen minimum zone with lowest open-ocean oxygen (O 2 ) concentrations of approximately 40 μmol kg −1 . The recent discovery of re-occurring mesoscale eddies with close to anoxic O 2 concentrations (< 1 μmol kg −1 ) located just below the mixed layer has challenged our understanding of O 2 distribution and biogeochemical processes in this area. Here, we present the first microbial community study from a deoxygenated anticyclonic modewater eddy in the open waters of the ETNA. In the eddy, we observed significantly lower bacterial diversity compared to surrounding waters, along with a significant community shift. We detected enhanced primary productivity in the surface layer of the eddy indicated by elevated chlorophyll concentrations and carbon uptake rates of up to three times as high as in surrounding waters. Carbon uptake rates below the euphotic zone correlated to the presence of a specific high-light ecotype of Prochlorococcus , which is usually underrepresented in the ETNA. Our data indicate that high primary production in the eddy fuels export production and supports enhanced respiration in a specific microbial community at shallow depths, below the mixed-layer base. The transcription of the key functional marker gene for dentrification, nirS , further indicated a potential for nitrogen loss processes in O 2 -depleted core waters of the eddy. Dentrification is usually absent from the open ETNA waters. In light of future projected ocean deoxygenation, our results show that even distinct events of anoxia have the potential to alter microbial community structure with critical impacts on primary productivity and biogeochemical processes of oceanic water bodies. Article in Journal/Newspaper North Atlantic Directory of Open Access Journals: DOAJ Articles Biogeosciences 12 24 7467 7482 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
spellingShingle |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 C. R. Löscher M. A. Fischer S. C. Neulinger B. Fiedler M. Philippi F. Schütte A. Singh H. Hauss J. Karstensen A. Körtzinger S. Künzel R. A. Schmitz Hidden biosphere in an oxygen-deficient Atlantic open-ocean eddy: future implications of ocean deoxygenation on primary production in the eastern tropical North Atlantic |
topic_facet |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
description |
The eastern tropical North Atlantic (ETNA) is characterized by a highly productive coastal upwelling system and a moderate oxygen minimum zone with lowest open-ocean oxygen (O 2 ) concentrations of approximately 40 μmol kg −1 . The recent discovery of re-occurring mesoscale eddies with close to anoxic O 2 concentrations (< 1 μmol kg −1 ) located just below the mixed layer has challenged our understanding of O 2 distribution and biogeochemical processes in this area. Here, we present the first microbial community study from a deoxygenated anticyclonic modewater eddy in the open waters of the ETNA. In the eddy, we observed significantly lower bacterial diversity compared to surrounding waters, along with a significant community shift. We detected enhanced primary productivity in the surface layer of the eddy indicated by elevated chlorophyll concentrations and carbon uptake rates of up to three times as high as in surrounding waters. Carbon uptake rates below the euphotic zone correlated to the presence of a specific high-light ecotype of Prochlorococcus , which is usually underrepresented in the ETNA. Our data indicate that high primary production in the eddy fuels export production and supports enhanced respiration in a specific microbial community at shallow depths, below the mixed-layer base. The transcription of the key functional marker gene for dentrification, nirS , further indicated a potential for nitrogen loss processes in O 2 -depleted core waters of the eddy. Dentrification is usually absent from the open ETNA waters. In light of future projected ocean deoxygenation, our results show that even distinct events of anoxia have the potential to alter microbial community structure with critical impacts on primary productivity and biogeochemical processes of oceanic water bodies. |
format |
Article in Journal/Newspaper |
author |
C. R. Löscher M. A. Fischer S. C. Neulinger B. Fiedler M. Philippi F. Schütte A. Singh H. Hauss J. Karstensen A. Körtzinger S. Künzel R. A. Schmitz |
author_facet |
C. R. Löscher M. A. Fischer S. C. Neulinger B. Fiedler M. Philippi F. Schütte A. Singh H. Hauss J. Karstensen A. Körtzinger S. Künzel R. A. Schmitz |
author_sort |
C. R. Löscher |
title |
Hidden biosphere in an oxygen-deficient Atlantic open-ocean eddy: future implications of ocean deoxygenation on primary production in the eastern tropical North Atlantic |
title_short |
Hidden biosphere in an oxygen-deficient Atlantic open-ocean eddy: future implications of ocean deoxygenation on primary production in the eastern tropical North Atlantic |
title_full |
Hidden biosphere in an oxygen-deficient Atlantic open-ocean eddy: future implications of ocean deoxygenation on primary production in the eastern tropical North Atlantic |
title_fullStr |
Hidden biosphere in an oxygen-deficient Atlantic open-ocean eddy: future implications of ocean deoxygenation on primary production in the eastern tropical North Atlantic |
title_full_unstemmed |
Hidden biosphere in an oxygen-deficient Atlantic open-ocean eddy: future implications of ocean deoxygenation on primary production in the eastern tropical North Atlantic |
title_sort |
hidden biosphere in an oxygen-deficient atlantic open-ocean eddy: future implications of ocean deoxygenation on primary production in the eastern tropical north atlantic |
publisher |
Copernicus Publications |
publishDate |
2015 |
url |
https://doi.org/10.5194/bg-12-7467-2015 https://doaj.org/article/1c2c5953f7bf4f268c8973e1fc43f226 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
Biogeosciences, Vol 12, Iss 24, Pp 7467-7482 (2015) |
op_relation |
http://www.biogeosciences.net/12/7467/2015/bg-12-7467-2015.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 1726-4170 1726-4189 doi:10.5194/bg-12-7467-2015 https://doaj.org/article/1c2c5953f7bf4f268c8973e1fc43f226 |
op_doi |
https://doi.org/10.5194/bg-12-7467-2015 |
container_title |
Biogeosciences |
container_volume |
12 |
container_issue |
24 |
container_start_page |
7467 |
op_container_end_page |
7482 |
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1766129404270870528 |