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Author
Stukel, M.R. ; Decima, M. ; Kelly, T.B.
Title
A new approach for incorporating 15N isotopic data into linear inverse ecosystem models with Markov Chain Monte Carlo sampling
Type
$loc['typeJournal Article']
Year
2018
Publication
PloS one
Abbreviated Journal
PLoS One
Volume
13
Issue
6
Pages
e0199123
Keywords
Isotopic data ; Nitrogen-based ecosystem models ; Phytoplankton ; Defecation by grazers ; Mortality by phytoplankton
Abstract
Oceanographic field programs often use delta15N biogeochemical measurements and in situ rate measurements to investigate nitrogen cycling and planktonic ecosystem structure. However, integrative modeling approaches capable of synthesizing these distinct measurement types are lacking. We develop a novel approach for incorporating delta15N isotopic data into existing Markov Chain Monte Carlo (MCMC) random walk methods for solving linear inverse ecosystem models. We test the ability of this approach to recover food web indices (nitrate uptake, nitrogen fixation, zooplankton trophic level, and secondary production) derived from forward models simulating the planktonic ecosystems of the California Current and Amazon River Plume. We show that the MCMC with delta15N approach typically does a better job of recovering ecosystem structure than the standard MCMC or L2 minimum norm (L2MN) approaches, and also outperforms an L2MN with delta15N approach. Furthermore, we find that the MCMC with delta15N approach is robust to the removal of input equations and hence is well suited to typical pelagic ecosystem studies for which the system is usually vastly under-constrained. Our approach is easily extendable for use with delta13C isotopic measurements or variable carbon:nitrogen stoichiometry.
Address
Department of Earth, Ocean, and Atmospheric Science, Florida State University, Tallahassee, FL, United States of America
Corporate Author
Thesis
Publisher
Place of Publication
Editor
Language
English
Summary Language
Original Title
Series Editor
Series Title
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Series Volume
Series Issue
Edition
ISSN
1932-6203
ISBN
Medium
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Conference
Funding
strtoupper('2').strtolower('9912928'); strtoupper('P').strtolower('MC6005467')
Approved
$loc['no']
Call Number
COAPS @ user @
Serial
975
Permanent link to this record
Author
Stukel, M.R. ; Décima, M. ; Landry, M.R. ; Selph, K.E.
Title
Nitrogen and isotope flows through the Costa Rica Dome upwelling ecosystem: The crucial mesozooplankton role in export flux
Type
$loc['typeJournal Article']
Year
2018
Publication
Global Biogeochemical Cycles
Abbreviated Journal
Global Biogeochemical Cycles
Volume
32
Issue
12
Pages
1815–1832.
Keywords
Crustaceans ; Diel vertical migration ; Nitrogen cycle ; Biological carbon pump ; Nitrogen isotopes ; Linear inverse ecosystem model
Abstract
The Costa Rica Dome (CRD) is an open-ocean upwelling ecosystem, with high biomasses of picophytoplankton (especially Synechococcus), mesozooplankton, and higher trophic levels. To elucidate the food web pathways supporting the trophic structure and carbon export in this unique ecosystem, we used Markov Chain Monte Carlo techniques to assimilate data from four independent realizations of δ15N and planktonic rate measurements from the CRD into steady state, multicompartment ecosystem box models (linear inverse models). Model results present well-constrained snapshots of ecosystem nitrogen and stable isotope fluxes. New production is supported by upwelled nitrate, not nitrogen fixation. Protistivory (rather than herbivory) was the most important feeding mode for mesozooplankton, which rely heavily on microzooplankton prey. Mesozooplankton play a central role in vertical nitrogen export, primarily through active transport of nitrogen consumed in the surface layer and excreted at depth, which comprised an average 36-46% of total export. Detritus or aggregate feeding is also an important mode of resource acquisition by mesozooplankton and regeneration of nutrients within the euphotic zone. As a consequence, the ratio of passively sinking particle export to phytoplankton production is very low in the CRD. Comparisons to similar models constrained with data from the nearby equatorial Pacific demonstrate that the dominant role of vertical migrators to the biological pump is a unique feature of the CRD. However, both regions show efficient nitrogen transfer from mesozooplankton to higher trophic levels (as expected for regions with large fish, cetacean, and seabird populations) despite the dominance of protists as major grazers of phytoplankton.
Address
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Series Issue
Edition
ISSN
ISBN
Medium
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Approved
$loc['no']
Call Number
COAPS @ rl18 @
Serial
978
Permanent link to this record
Author
Stukel, M.R. ; Ohman, M.D. ; Kelly, T.B. ; Biard, T.
Title
The Roles of Suspension-Feeding and Flux-Feeding Zooplankton as Gatekeepers of Particle Flux Into the Mesopelagic Ocean in the Northeast Pacific
Type
$loc['typeJournal Article']
Year
2019
Publication
Frontiers in Marine Science
Abbreviated Journal
Front. Mar. Sci.
Volume
6
Issue
Pages
Keywords
biological pump ; carbon export ; remineralization length scale ; mesozooplankton ecology ; pteropods ; marine biogeochemistry ; sinking particles ; marine snow
Abstract
Zooplankton are important consumers of sinking particles in the ocean's twilight zone. However, the impact of different taxa depends on their feeding mode. In contrast to typical suspension-feeding zooplankton, flux-feeding taxa preferentially consume rapidly sinking particles that would otherwise penetrate into the deep ocean. To quantify the potential impact of two flux-feeding zooplankton taxa [Aulosphaeridae (Rhizaria), and Limacina helicina (euthecosome pteropod)] and the total suspension-feeding zooplankton community, we measured depth-stratified abundances of these organisms during six cruises in the California Current Ecosystem. Using allometric-scaling relationships, we computed the percentage of carbon flux intercepted by flux feeders and suspension feeders. These estimates were compared to direct measurements of carbon flux attenuation (CFA) made using drifting sediment traps and U-238-Th-234 disequilibrium. We found that CFA in the shallow twilight zone typically ranged from 500 to 1000 m mol organic C flux remineralized per 10-m vertical depth bin. This equated to approximately 6-10% of carbon flux remineralized/10 m. The two flux-feeding taxa considered in this study could account for a substantial proportion of this flux near the base of the euphotic zone. The mean flux attenuation attributable to Aulosphaeridae was 0.69%/10 m (median = 0.21%/10 m, interquartile range = 0.04-0.81%) at their depth of maximum abundance (similar to 100 m), which would equate to similar to 10% of total flux attenuation in this depth range. The maximum flux attenuation attributable to Aulosphaeridae reached 4.2%/10 m when these protists were most abundant. L. helicina, meanwhile, could intercept 0.45-1.6% of carbon flux/10 m, which was slightly greater (on average) than the Aulosphaeridae. In contrast, suspension-feeding zooplankton in the mesopelagic (including copepods, euphausiids, appendicularians, and ostracods) had combined clearance rates of 2-81 L m(-3) day(-1) (mean of 19.6 L m(-3) day(-1)). This implies a substantial impact on slowly sinking particles, but a negligible impact on the presumably rapidly sinking fecal pellets that comprised the majority of the material collected in sediment traps. Our results highlight the need for a greater research focus on the many taxa that potentially act as flux feeders in the oceanic twilight zone.
Address
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Series Editor
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Series Issue
Edition
ISSN
2296-7745
ISBN
Medium
Area
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Conference
Funding
Approved
$loc['no']
Call Number
COAPS @ user @
Serial
1066
Permanent link to this record
Author
Subrahmanyam, B. ; Babu, V.R. ; Murty, V.S.N. ; Rao, L.V.G.
Title
Surface circulation off Somalia and western equatorial Indian Ocean during summer monsoon of 1988 from Geosat altimeter data
Type
$loc['typeJournal Article']
Year
1996
Publication
International Journal of Remote Sensing
Abbreviated Journal
International Journal of Remote Sensing
Volume
17
Issue
4
Pages
761-770
Keywords
Abstract
Address
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Place of Publication
Editor
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Summary Language
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Series Editor
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Series Volume
Series Issue
Edition
ISSN
0143-1161
ISBN
Medium
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Funding
Approved
$loc['no']
Call Number
COAPS @ mfield @
Serial
713
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Author
Subrahmanyam, B. ; Legler, D. M. ; Barnier, B. ; de Miranda, A. P. ; O'Brien, J. J.
Title
Sensitivity of the North Atlantic circulation to momentum forcing using SPEM
Type
$loc['typeConference Article']
Year
2000
Publication
IGARSS 2000, Honolulu, Hawaii, USA
Abbreviated Journal
Volume
Issue
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ISBN
Medium
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Approved
$loc['no']
Call Number
COAPS @ mfield @
Serial
797
Permanent link to this record
Author
Subrahmanyam, B. ; Legler, D. M. ; Barnier, B. ; O'Brien, J. J. ; de Miranda, A. P. ; Bourassa, M.
Title
Sensitivity of an ocean general circulation model to changes in surface momentum forcing
Type
$loc['typeConference Article']
Year
2001
Publication
Abbreviated Journal
Volume
Issue
Pages
Keywords
Abstract
Address
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Place of Publication
Editor
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Summary Language
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Series Editor
Series Title
WMO WORLD Climate Research Programme, CAS/JSC Working Group on Numerical Experimentation, Research Activities in Atmospheric and Oceanic Modeling
Abbreviated Series Title
Series Volume
Series Issue
Edition
ISSN
ISBN
Medium
Area
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Conference
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Approved
$loc['no']
Call Number
COAPS @ mfield @
Serial
822
Permanent link to this record
Author
Subrahmanyam, B. ; Legler, D. M. ; O'Brien, J. J.
Title
), Indian Ocean Circulation using TOPEX/POSEIDION Altimetry and Model Simulations
Type
$loc['typeReport']
Year
1999
Publication
Abbreviated Journal
Volume
28
Issue
Pages
Keywords
Abstract
Address
Corporate Author
Thesis
Publisher
Place of Publication
Editor
Ritchie, H.
Language
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Series Editor
Series Title
Research activities in Atmospheric and Oceanic Modeling
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ISBN
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$loc['no']
Call Number
COAPS @ mfield @
Serial
776
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Author
Subrahmanyam, B. ; Legler, D. M. ; O'Brien, J. J.
Title
Response of the North Atlantic circulation with surface momentum forcing using SPEM Model
Type
$loc['typeReport']
Year
2000
Publication
Abbreviated Journal
Volume
Issue
Pages
9.13-9.14
Keywords
Abstract
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Publisher
Place of Publication
Editor
Ritchie, H.
Language
Summary Language
Original Title
Series Editor
Series Title
WMO World Climate Research Programme, CAS/JSC Working Group on Numerical Experimentation, Research Activities in Atmospheric and Oceanic Modeling, Report No. 30 (WMO/TD-No.987)
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ISBN
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$loc['no']
Call Number
COAPS @ mfield @
Serial
801
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Author
Subrahmanyam, B. ; Manghanai, V. ; O'Brien, J. J. ; Morrison, J. M. ; Xie, L.
Title
A study of the Indian Ocean Dipole Mode Dynamics using satellite observations and MICOM simulations
Type
$loc['typeConference Article']
Year
2001
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Issue
Pages
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Abstract
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Place of Publication
San Diego, California, USA
Editor
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ISBN
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$loc['no']
Call Number
COAPS @ mfield @
Serial
823
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Author
Subrahmanyam, B. ; Murty, V. S. N. ; O'Brien, J. J.
Title
New Sea Surface Salinity Product in the Tropical Indian Ocean
Type
$loc['typeReport']
Year
2005
Publication
Abbreviated Journal
Volume
Issue
Pages
Keywords
Abstract
Address
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Series Editor
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CAS/JSC Working Group on Numerical Experimentation
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Series Issue
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ISBN
Medium
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Approved
$loc['no']
Call Number
COAPS @ mfield @
Serial
897
Permanent link to this record