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Author Landry, M.R.; Selph, K.E.; Decima, M.; Gutierrez-Rodriguez, A.; Stukel, M.R.; Taylor, A.G.; Pasulka, A.L.
Title Phytoplankton production and grazing balances 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 366-379
Keywords grazing; plankton community; productivity
Abstract We investigated phytoplankton production rates and grazing fates in the Costa Rica Dome (CRD) during summer 2010 based on dilution depth profiles analyzed by flow cytometry and pigments and mesozooplankton grazing assessed by gut fluorescence. Three community production estimates, from 14C uptake (1025 +/- 113 mg C m-2 day-1) and from dilution experiments analyzed for total Chla (990 +/- 106 mg C m-2 day-1) and flow cytometry populations (862 +/- 71 mg C m-2 day-1), exceeded regional ship-based values by 2-3-fold. Picophytoplankton accounted for 56% of community biomass and 39% of production. Production profiles extended deeper for Prochlorococcus (PRO) and picoeukaryotes than for Synechococcus (SYN) and larger eukaryotes, but 93% of total production occurred above 40 m. Microzooplankton consumed all PRO and SYN growth and two-third of total production. Positive net growth of larger eukaryotes in the upper 40 m was balanced by independently measured consumption by mesozooplankton. Among larger eukaryotes, diatoms contributed approximately 3% to production. On the basis of this analysis, the CRD region is characterized by high production and grazing turnover, comparable with or higher than estimates for the eastern equatorial Pacific. The region nonetheless displays characteristics atypical of high productivity, such as picophytoplankton dominance and suppressed diatom roles.
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:27275036; PMCID:PMC4889984 Approved $loc['no']
Call Number COAPS @ mfield @ Serial 85
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Author Morrow, R.M.; Ohman, M.D.; Goericke, R.; Kelly, T.B.; Stephens, B.M.; Stukel, M.R.
Title CCE V: Primary production, mesozooplankton grazing, and the biological pump in the California Current Ecosystem: Variability and response to El Niño Type $loc['typeJournal Article']
Year 2018 Publication Deep Sea Research Part I: Oceanographic Research Papers Abbreviated Journal Deep Sea Research Part I: Oceanographic Research Papers
Volume 140 Issue Pages 52-62
Keywords Carbon export; Fecal pellets; Sinking particles; Interannual variability; Net primary productivity; Eastern boundary upwelling system KeyWords Plus:ZOOPLANKTON FECAL PELLETS; NORTH PACIFIC-OCEAN; CURRENT SYSTEM; SOUTHERN CALIFORNIA; UNDERWATER GLIDERS; CARBON EXPORT; ZONE; CHLOROPHYLL; STABILITY; EQUATIONS
Abstract Predicting marine carbon sequestration in a changing climate requires mechanistic understanding of the processes controlling sinking particle flux under different climatic conditions. The recent occurrence of a warm anomaly (2014-2015) followed by an El Nino (2015-2016) in the southern sector of the California Current System presented an opportunity to analyze changes in the biological carbon pump in response to altered climate forcing. We compare primary production, mesozooplankton grazing, and carbon export from the euphotic zone during quasi-Lagrangian experiments conducted in contrasting conditions: two cruises during warm years – one during the warm anomaly in 2014 and one toward the end of El Nino 2016 – and three cruises during El Ninoneutral years. Results showed no substantial differences in the relationships between vertical carbon export and its presumed drivers (primary production, mesozooplankton grazing) between warm and neutral years. Mesozooplankton fecal pellet enumeration and phaeopigment measurements both showed that fecal pellets were the dominant contributor to export in productive upwelling regions. In more oligotrophic regions, fluxes were dominated by amorphous marine snow with negligible pigment content. We found no evidence for a significant shift in the relationship between mesozooplankton grazing rate and chlorophyll concentration. However, massspecific grazing rates were lower at low-to-moderate chlorophyll concentrations during warm years relative to neutral years. We also detected a significant difference in the relationship between phytoplankton primary production and photosynthetically active radiation between years: at similar irradiance and nutrient concentrations, productivity decreased during the warm events. Whether these changes resulted from species composition changes remains to be determined. Overall, our results suggest that the processes driving export remain similar during different climate conditions, but that species compositional changes or other structural changes require further attention.
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 0967-0637 ISBN Medium
Area Expedition Conference
Funding Approved $loc['no']
Call Number COAPS @ rl18 @ Serial 983
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Author Morrow, R.M.; Ohman, M.D.; Goericke, R.; Kelly, T.B.; Stephens, B.M.; Stukel, M.R.
Title CCE V: Primary production, mesozooplankton grazing, and the biological pump in the California Current Ecosystem: Variability and response to El Niño Type $loc['typeJournal Article']
Year 2018 Publication Deep Sea Research Part I: Oceanographic Research Papers Abbreviated Journal Deep Sea Research Part I: Oceanographic Research Papers
Volume Issue Pages
Keywords Carbon export; Fecal pellets; Sinking particles; Interannual variability; Net primary productivity; Eastern boundary upwelling system
Abstract Predicting marine carbon sequestration in a changing climate requires mechanistic understanding of the processes controlling sinking particle flux under different climatic conditions. The recent occurrence of a warm anomaly (2014�2015) followed by an El Niño (2015�2016) in the southern sector of the California Current System presented an opportunity to analyze changes in the biological carbon pump in response to altered climate forcing. We compare primary production, mesozooplankton grazing, and carbon export from the euphotic zone during quasi-Lagrangian experiments conducted in contrasting conditions: two cruises during warm years – one during the warm anomaly in 2014 and one toward the end of El Niño 2016 � and three cruises during El Niño-neutral years. Results showed no substantial differences in the relationships between vertical carbon export and its presumed drivers (primary production, mesozooplankton grazing) between warm and neutral years. Mesozooplankton fecal pellet enumeration and phaeopigment measurements both showed that fecal pellets were the dominant contributor to export in productive upwelling regions. In more oligotrophic regions, fluxes were dominated by amorphous marine snow with negligible pigment content. We found no evidence for a significant shift in the relationship between mesozooplankton grazing rate and chlorophyll concentration. However, mass-specific grazing rates were lower at low-to-moderate chlorophyll concentrations during warm years relative to neutral years. We also detected a significant difference in the relationship between phytoplankton primary production and photosynthetically active radiation between years: at similar irradiance and nutrient concentrations, productivity decreased during the warm events. Whether these changes resulted from species composition changes remains to be determined. Overall, our results suggest that the processes driving export remain similar during different climate conditions, but that species compositional changes or other structural changes require further attention
Address Deep-Sea Research Part I
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 0967-0637 ISBN Medium
Area Expedition Conference
Funding Approved $loc['no']
Call Number COAPS @ user @ Serial 966
Permanent link to this record
 

 
Author Morrow, R.M.; Ohman, M.D.; Goericke, R.; Kelly, T.B.; Stephens, B.M.; Stukel, M.R.
Title CCE V: Primary production, mesozooplankton grazing, and the biological pump in the California Current Ecosystem: Variability and response to El Niño Type $loc['typeJournal Article']
Year 2018 Publication Deep Sea Research Part I: Oceanographic Research Papers Abbreviated Journal Deep Sea Research Part I: Oceanographic Research Papers
Volume 140 Issue Pages 52-62
Keywords Carbon export; Fecal pellets; Sinking particles; Interannual variability; Net primary productivity; Eastern boundary upwelling system
Abstract Predicting marine carbon sequestration in a changing climate requires mechanistic understanding of the processes controlling sinking particle flux under different climatic conditions. The recent occurrence of a warm anomaly (2014-2015) followed by an El Nino (2015-2016) in the southern sector of the California Current System presented an opportunity to analyze changes in the biological carbon pump in response to altered climate forcing. We compare primary production, mesozooplankton grazing, and carbon export from the euphotic zone during quasi-Lagrangian experiments conducted in contrasting conditions: two cruises during warm years – one during the warm anomaly in 2014 and one toward the end of El Nino 2016 – and three cruises during El Ninoneutral years. Results showed no substantial differences in the relationships between vertical carbon export and its presumed drivers (primary production, mesozooplankton grazing) between warm and neutral years. Mesozooplankton fecal pellet enumeration and phaeopigment measurements both showed that fecal pellets were the dominant contributor to export in productive upwelling regions. In more oligotrophic regions, fluxes were dominated by amorphous marine snow with negligible pigment content. We found no evidence for a significant shift in the relationship between mesozooplankton grazing rate and chlorophyll concentration. However, massspecific grazing rates were lower at low-to-moderate chlorophyll concentrations during warm years relative to neutral years. We also detected a significant difference in the relationship between phytoplankton primary production and photosynthetically active radiation between years: at similar irradiance and nutrient concentrations, productivity decreased during the warm events. Whether these changes resulted from species composition changes remains to be determined. Overall, our results suggest that the processes driving export remain similar during different climate conditions, but that species compositional changes or other structural changes require further attention.
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 0967-0637 ISBN Medium
Area Expedition Conference
Funding Approved $loc['no']
Call Number COAPS @ user @ Serial 1021
Permanent link to this record
 

 
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 Shropshire, T.; Morey, S. L.; Chassignet, E. P.; Bozec, A.; Coles, V.J.; Landry, M.R.; Swalethorp, R.; Zapfe, G. and Stukel, M.R.
Title Quantifying spatiotemporal variability in zooplankton dynamics in the Gulf of Mexico with a physical-biogeochemical model Type $loc['typeJournal Article']
Year 2019 Publication Abbreviated Journal
Volume Issue Pages
Keywords
Abstract Zooplankton play an important role in global biogeochemistry and their secondary production supports valuable fisheries of the world's oceans. Currently, zooplankton abundances cannot be estimated using remote sensing techniques. Hence, coupled physical-biogeochemical models (PBMs) provide an important tool for studying zooplankton on regional and global scales. However, evaluating the accuracy of zooplankton abundance estimates from PBMs has been a major challenge as a result of sparse observations. In this study, we configure a PBM for the Gulf of Mexico (GoM) from 1993&#65533;2012 and validate the model against an extensive combination of in situ biomass and rate measurements including total mesozooplankton biomass, size-fractionated mesozooplankton biomass and grazing rates, microzooplankton specific grazing rates, surface chlorophyll, deep chlorophyll maximum depth, phytoplankton specific growth rates, and net primary production. Spatial variability in mesozooplankton biomass climatology observed in a multi-decadal database for the northern GoM is well resolved by the model with a statistically significant (p&#8201;<&#8201;0.01) correlation of 0.90. Mesozooplankton secondary production for the region averaged 66&#8201;+&#8201;8&#8201;mt&#8201;C&#8201;yr&#8722;1 equivalent to approximately 10&#8201;% of NPP and ranged from 51 to 82&#8201;mt&#8201;C&#8201;yr&#8722;1. In terms of diet, model results from the shelf regions suggest that herbivory is the dominant feeding mode for small mesozooplankton (<&#8201;1-mm) whereas larger mesozooplankton are primarily carnivorous. However, in open-ocean, oligotrophic regions, both groups of mesozooplankton have proportionally greater reliance on heterotrophic protists as a food source. This highlights the important role of microbial and protistan food webs in sustaining mesozooplankton biomass in the GoM which serves as the primary food source for early life stages of many commercially-important fish species, including tuna.
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 ISBN Medium
Area Expedition Conference
Funding Approved $loc['no']
Call Number COAPS @ user @ Serial 1095
Permanent link to this record
 

 
Author Stukel, M.R.; Barbeau, K.A.
Title Investigating the Nutrient Landscape in a Coastal Upwelling Region and Its Relationship to the Biological Carbon Pump Type $loc['typeJournal Article']
Year 2020 Publication Geophysical Research Letters Abbreviated Journal Geophys. Res. Lett.
Volume 47 Issue 6 Pages e2020GL087351
Keywords
Abstract We investigated nutrient patterns and their relationship to vertical carbon export using results from 38 Lagrangian experiments in the California Current Ecosystem. The dominant mode of variability reflected onshore-offshore nutrient gradients. A secondary mode of variability was correlated with silica excess and dissolved iron and likely reflects regional patterns of iron-limitation. The biological carbon pump was enhanced in high nutrient and Fe-stressed regions. Patterns in the nutrient landscape proved to be better predictors of the vertical flux of sinking particles than contemporaneous measurements of net primary production. Our results suggest an important role for Fe-stressed diatoms in vertical carbon flux. They also suggest that either preferential recycling of N or non-Redfieldian nutrient uptake by diatoms may lead to high PO:NO and Si(OH):NO ratios, following export of P- and Si-enriched organic matter. Increased export following Fe-stress may partially explain inverse relationships between net primary productivity and export efficiency.
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 0094-8276 ISBN Medium
Area Expedition Conference
Funding Approved $loc['no']
Call Number COAPS @ user @ Serial 1112
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Author Stukel, M.R.; Ducklow, H.W.
Title Stirring Up the Biological Pump: Vertical Mixing and Carbon Export in the Southern Ocean Type $loc['typeJournal Article']
Year 2017 Publication Global Biogeochemical Cycles Abbreviated Journal Global Biogeochem. Cycles
Volume 31 Issue 9 Pages 1420-1434
Keywords
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 0886-6236 ISBN Medium
Area Expedition Conference
Funding Approved $loc['no']
Call Number COAPS @ mfield @ Serial 361
Permanent link to this record
 

 
Author Stukel, M.R.; Kelly, T.B.
Title The carbon: 234Thorium 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 Publication Marine Chemistry Abbreviated Journal Marine Chemistry
Volume Issue Pages
Keywords
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 0304-4203 ISBN Medium
Area Expedition Conference
Funding Approved $loc['no']
Call Number COAPS @ user @ Serial 1037
Permanent link to this record
 

 
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
Permanent link to this record

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