Increased ocean carbon export in the Sargasso Sea linked to climate variability is countered by its enhanced mesopelagic attenuation
Photosynthetic CO<sub>2</sub> uptake by oceanic phytoplankton and subsequent export of particulate organic carbon (POC) to the ocean interior comprises a globally significant biological carbon pump, controlled in part by the composition of the planktonic community. The strength and effic...
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2010-01-01
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| Series: | Biogeosciences |
| Online Access: | http://www.biogeosciences.net/7/57/2010/bg-7-57-2010.pdf |
| _version_ | 1828771942395543552 |
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| author | M. W. Lomas D. K. Steinberg T. Dickey C. A. Carlson N. B. Nelson R. H. Condon N. R. Bates |
| author_facet | M. W. Lomas D. K. Steinberg T. Dickey C. A. Carlson N. B. Nelson R. H. Condon N. R. Bates |
| author_sort | M. W. Lomas |
| collection | DOAJ |
| description | Photosynthetic CO<sub>2</sub> uptake by oceanic phytoplankton and subsequent
export of particulate organic carbon (POC) to the ocean interior comprises a
globally significant biological carbon pump, controlled in part by the
composition of the planktonic community. The strength and efficiency of this
pump depends upon the balance of particle production in the euphotic zone
and remineralization of those particles in the mesopelagic (defined here as
depths between 150 and 300 m), but how these processes respond to
climate-driven changes in the physical environment is not completely
understood. In the Sargasso Sea, from ~1996–2007, we have observed a
decade-long >50% increase in euphotic zone integrated autotrophic
biomass (estimated from chlorophyll TChl-<i>α</i>), prokaryotic phytoplankton,
primary production and shallow (150 m) POC export coinciding with a shift in
the mean phase of the winter North Atlantic Oscillation (NAO) from
consistently positive to neutral but variable. During this same period
mesopelagic POC flux attenuation has doubled such that carbon sequestration
below 300 m, the maximum winter/spring ventilation depth, has not changed.
The increased mesopelagic POC attenuation appears mediated by changes in
plankton community composition and metabolic activity in both the euphotic
and mesopelagic zones. These changes are counter to extant hypotheses
regarding inter-relationships between phytoplankton community composition,
productivity and carbon export, and have significant impacts on how the
Sargasso Sea ecosystem, at least, is modeled. Moreover, these time-series
observations suggest that processes in the euphotic zone and mesopelagic are
tightly coupled and should be considered together in future research. |
| first_indexed | 2024-12-11T14:34:43Z |
| format | Article |
| id | doaj.art-1ec02362173040989c2352440c86addc |
| institution | Directory Open Access Journal |
| issn | 1726-4170 1726-4189 |
| language | English |
| last_indexed | 2024-12-11T14:34:43Z |
| publishDate | 2010-01-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj.art-1ec02362173040989c2352440c86addc2022-12-22T01:02:13ZengCopernicus PublicationsBiogeosciences1726-41701726-41892010-01-0171577010.5194/bg-7-57-2010Increased ocean carbon export in the Sargasso Sea linked to climate variability is countered by its enhanced mesopelagic attenuationM. W. Lomas0D. K. Steinberg1T. Dickey2C. A. Carlson3N. B. Nelson4R. H. Condon5N. R. Bates6Bermuda Institute of Ocean Sciences, 17 Biological Lane, St. George's, GE01, BermudaVirginia Institute of Marine Science, The College of William and Mary, Chesapeake Bay Hall S206, P.O. Box 1346, Gloucester Pt., VA 23062-1346, USAOcean Physics Laboratory and Department of Geography, Ocean Physics Laboratory, EH 1629, University of California, Santa Barbara, CA 93106-3060, USADepartment of Ecology, Evolution and Marine Biology, Marine Biotechnology Building, Room 3147, University of California, Santa Barbara, CA 93106-3060, USAInstitute for Computational Earth System Science, Mail Code 3060, University of California, Santa Barbara, CA 93106-3060, USABermuda Institute of Ocean Sciences, 17 Biological Lane, St. George's, GE01, BermudaBermuda Institute of Ocean Sciences, 17 Biological Lane, St. George's, GE01, BermudaPhotosynthetic CO<sub>2</sub> uptake by oceanic phytoplankton and subsequent export of particulate organic carbon (POC) to the ocean interior comprises a globally significant biological carbon pump, controlled in part by the composition of the planktonic community. The strength and efficiency of this pump depends upon the balance of particle production in the euphotic zone and remineralization of those particles in the mesopelagic (defined here as depths between 150 and 300 m), but how these processes respond to climate-driven changes in the physical environment is not completely understood. In the Sargasso Sea, from ~1996–2007, we have observed a decade-long >50% increase in euphotic zone integrated autotrophic biomass (estimated from chlorophyll TChl-<i>α</i>), prokaryotic phytoplankton, primary production and shallow (150 m) POC export coinciding with a shift in the mean phase of the winter North Atlantic Oscillation (NAO) from consistently positive to neutral but variable. During this same period mesopelagic POC flux attenuation has doubled such that carbon sequestration below 300 m, the maximum winter/spring ventilation depth, has not changed. The increased mesopelagic POC attenuation appears mediated by changes in plankton community composition and metabolic activity in both the euphotic and mesopelagic zones. These changes are counter to extant hypotheses regarding inter-relationships between phytoplankton community composition, productivity and carbon export, and have significant impacts on how the Sargasso Sea ecosystem, at least, is modeled. Moreover, these time-series observations suggest that processes in the euphotic zone and mesopelagic are tightly coupled and should be considered together in future research.http://www.biogeosciences.net/7/57/2010/bg-7-57-2010.pdf |
| spellingShingle | M. W. Lomas D. K. Steinberg T. Dickey C. A. Carlson N. B. Nelson R. H. Condon N. R. Bates Increased ocean carbon export in the Sargasso Sea linked to climate variability is countered by its enhanced mesopelagic attenuation Biogeosciences |
| title | Increased ocean carbon export in the Sargasso Sea linked to climate variability is countered by its enhanced mesopelagic attenuation |
| title_full | Increased ocean carbon export in the Sargasso Sea linked to climate variability is countered by its enhanced mesopelagic attenuation |
| title_fullStr | Increased ocean carbon export in the Sargasso Sea linked to climate variability is countered by its enhanced mesopelagic attenuation |
| title_full_unstemmed | Increased ocean carbon export in the Sargasso Sea linked to climate variability is countered by its enhanced mesopelagic attenuation |
| title_short | Increased ocean carbon export in the Sargasso Sea linked to climate variability is countered by its enhanced mesopelagic attenuation |
| title_sort | increased ocean carbon export in the sargasso sea linked to climate variability is countered by its enhanced mesopelagic attenuation |
| url | http://www.biogeosciences.net/7/57/2010/bg-7-57-2010.pdf |
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