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Author Brzezinski, M.A.; Krause, J.W.; Bundy, R.M.; Barbeau, K.A.; Franks, P.; Goericke, R.; Landry, M.R.; Stukel, M.R.
Title Enhanced silica ballasting from iron stress sustains carbon export in a frontal zone within the California Current Type $loc['typeJournal Article']
Year 2015 Publication Journal of Geophysical Research: Oceans Abbreviated Journal J. Geophys. Res. Oceans
Volume 120 Issue 7 Pages 4654-4669
Keywords phytoplankton; diatoms; iron limitation; nutrient ratios; nutrient stoichiometry; carbon export
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2169-9275 ISBN Medium
Area Expedition Conference
Funding Approved $loc['no']
Call Number COAPS @ mfield @ Serial 97
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Author Selph, K.E.; Landry, M.R.; Taylor, A.G.; Gutierrez-Rodriguez, A.; Stukel, M.R.; Wokuluk, J.; Pasulka, A.
Title Phytoplankton production and taxon-specific growth rates in the Costa Rica Dome Type $loc['typeJournal Article']
Year 2016 Publication Journal of Plankton Research Abbreviated Journal J Plankton Res
Volume 38 Issue 2 Pages 199-215
Keywords Costa Rica Dome; growth; microzooplankton; mortality; phytoplankton
Abstract During summer 2010, we investigated phytoplankton production and growth rates at 19 stations in the eastern tropical Pacific, where winds and strong opposing currents generate the Costa Rica Dome (CRD), an open-ocean upwelling feature. Primary production (14C-incorporation) and group-specific growth and net growth rates (two-treatment seawater dilution method) were estimated from samples incubated in situ at eight depths. Our cruise coincided with a mild El Nino event, and only weak upwelling was observed in the CRD. Nevertheless, the highest phytoplankton abundances were found near the dome center. However, mixed-layer growth rates were lowest in the dome center ( approximately 0.5-0.9 day-1), but higher on the edge of the dome ( approximately 0.9-1.0 day-1) and in adjacent coastal waters (0.9-1.3 day-1). We found good agreement between independent methods to estimate growth rates. Mixed-layer growth rates of Prochlorococcus and Synechococcus were largely balanced by mortality, whereas eukaryotic phytoplankton showed positive net growth ( approximately 0.5-0.6 day-1), that is, growth available to support larger (mesozooplankton) consumer biomass. These are the first group-specific phytoplankton rate estimates in this region, and they demonstrate that integrated primary production is high, exceeding 1 g C m-2 day-1 on average, even during a period of reduced upwelling.
Address Scripps Institution of Oceanography, 9500 Gilman Dr., La Jolla, CA 92093-0227, USA; Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0142-7873 ISBN Medium
Area Expedition Conference
Funding PMID:27275025; PMCID:PMC4889980 Approved $loc['no']
Call Number COAPS @ mfield @ Serial 112
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Author Stukel, M.R.; Kelly, T.B.
Title The carbon: (234) Thorium ratios of sinking particles in the California current ecosystem 2: Examination of a thorium sorption, desorption, and particle transport model Type $loc['typeJournal Article']
Year 2019 Publication Marine Chemistry Abbreviated Journal Marine Chemistry
Volume 212 Issue Pages 1-15
Keywords POC concentration; sinking particles.; depth and relationship with water; phytoplankton
Abstract Thorium-234 (234Th) is a powerful tracer of particle dynamics and the biological pump in the surface ocean; however, variability in carbon: thorium ratios of sinking particles adds substantial uncertainty to estimates of organic carbon export. We coupled a mechanistic thorium sorption and desorption model to a one-dimensional particle sinking model that uses realistic particle settling velocity spectra. The model generates estimates of 238U234Th disequilibrium, particulate organic carbon concentration, and the C:234Th ratio of sinking particles, which are then compared to in situ measurements from quasi-Lagrangian studies conducted on six cruises in the California Current Ecosystem. Broad patterns observed in in situ measurements, including decreasing C:234Th ratios with depth and a strong correlation between sinking C:234Th and the ratio of vertically-integrated particulate organic carbon (POC) to vertically-integrated total water column 234Th, were accurately recovered by models assuming either a power law distribution of sinking speeds or a double log normal distribution of sinking speeds. Simulations suggested that the observed decrease in C:234Th with depth may be driven by preferential remineralization of carbon by particle-attached microbes. However, an alternate model structure featuring complete consumption and/or disaggregation of particles by mesozooplankton (e.g. no preferential remineralization of carbon) was also able to simulate decreasing C:234Th with depth (although the decrease was weaker), driven by 234Th adsorption onto slowly sinking particles. Model results also suggest that during bloom decays C:234Th ratios of sinking particles should be higher than expected (based on contemporaneous water column POC), because high settling velocities minimize carbon remineralization during sinking.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-4203 ISBN Medium
Area Expedition Conference
Funding Approved $loc['no']
Call Number COAPS @ user @ Serial 1002
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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 Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1932-6203 ISBN Medium
Area Expedition Conference
Funding strtoupper('2').strtolower('9912928'); strtoupper('P').strtolower('MC6005467') Approved $loc['no']
Call Number COAPS @ user @ Serial 975
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