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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�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 < 0.01) correlation of 0.90. Mesozooplankton secondary production for the region averaged 66 + 8 mt C yr−1 equivalent to approximately 10 % of NPP and ranged from 51 to 82 mt C yr−1. In terms of diet, model results from the shelf regions suggest that herbivory is the dominant feeding mode for small mesozooplankton (< 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.
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Approved
$loc['no']
Call Number
COAPS @ user @
Serial
1095
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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.
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Approved
$loc['no']
Call Number
COAPS @ rl18 @
Serial
978
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Author
Kranz, S.A. ; Wang, S. ; Kelly, T.B. ; Stukel, M.R. ; Goericke, R. ; Landry, M.R. ; Cassar, N.
Title
Lagrangian Studies of Marine Production: A Multimethod Assessment of Productivity Relationships in the California Current Ecosystem Upwelling Region
Type
$loc['typeJournal Article']
Year
2020
Publication
Journal of Geophysical Research: Oceans
Abbreviated Journal
J. Geophys. Res. Oceans
Volume
125
Issue
6
Pages
Keywords
gross primary production ; long‐ ; term ecological research ; equilibrium inlet mass spectrometry ; carbon export ; net community production
Abstract
A multimethod process‐oriented investigation of diverse productivity measures in the California Current Ecosystem (CCE) Long‐Term Ecological Research study region, a complex physical environment, is presented. Seven multiday deployments covering a transition region from high to low productivity were conducted over two field expeditions (spring 2016 and summer 2017). Employing a Lagrangian study design, water parcels were followed over several days, comparing 24‐h in situ measurements (14C and 15NO3 ‐uptake, dilution estimates of phytoplankton growth, and microzooplankton grazing) with high‐resolution productivity measurements by fast repetition rate fluorometry (FRRF) and equilibrium inlet mass spectrometry (EIMS), and integrated carbon export measuremnts using sediment traps. Results show the importance of accounting for temporal and fine spatial scale variability when estimating ecosystem production. FRRF and EIMS measurements resolved diel patterns in gross primary and net community production. Diel productivity changes agreed well with comparably more traditional measurements. While differences in productivity metrics calculated over different time intervals were considerable, as those methods rely on different base assumptions, the data can be used to explain ecosystem processes which would otherwise have gone unnoticed. The processes resolved from this method comparison further understanding of temporal and spatial coupling and decoupling of surface productivity and potential carbon burial in a gradient from coastal to offshore ecosystems.
Address
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Thesis
Publisher
Place of Publication
Editor
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Summary Language
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Series Editor
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Series Issue
Edition
ISSN
2169-9275
ISBN
Medium
Area
Expedition
Conference
Funding
Approved
$loc['no']
Call Number
COAPS @ user @
Serial
1113
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Author
Stukel, M.R. ; Aluwihare, L.I. ; Barbeau, K.A. ; Chekalyuk, A.M. ; Goericke, R. ; Miller, A.J. ; Ohman, M.D. ; Ruacho, A. ; Song, H. ; Stephens, B.M. ; Landry, M.R.
Title
Mesoscale ocean fronts enhance carbon export due to gravitational sinking and subduction
Type
$loc['typeJournal Article']
Year
2017
Publication
Proceedings of the National Academy of Sciences of the United States of America
Abbreviated Journal
Proc Natl Acad Sci U S A
Volume
114
Issue
6
Pages
1252-1257
Keywords
biological carbon pump ; carbon cycle ; particle flux ; particulate organic carbon ; plankton
Abstract
Enhanced vertical carbon transport (gravitational sinking and subduction) at mesoscale ocean fronts may explain the demonstrated imbalance of new production and sinking particle export in coastal upwelling ecosystems. Based on flux assessments from 238U:234Th disequilibrium and sediment traps, we found 2 to 3 times higher rates of gravitational particle export near a deep-water front (305 mg Cm-2d-1) compared with adjacent water or to mean (nonfrontal) regional conditions. Elevated particle flux at the front was mechanistically linked to Fe-stressed diatoms and high mesozooplankton fecal pellet production. Using a data assimilative regional ocean model fit to measured conditions, we estimate that an additional approximately 225 mg Cm-2d-1 was exported as subduction of particle-rich water at the front, highlighting a transport mechanism that is not captured by sediment traps and is poorly quantified by most models and in situ measurements. Mesoscale fronts may be responsible for over a quarter of total organic carbon sequestration in the California Current and other coastal upwelling ecosystems.
Address
Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093
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
0027-8424
ISBN
Medium
Area
Expedition
Conference
Funding
PMID:28115723; PMCID:PMC5307443
Approved
$loc['no']
Call Number
COAPS @ mfield @
Serial
67
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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
Permanent link to this record
Author
Stukel, M.R. ; Benitez-Nelson, C.R. ; Decima, M. ; Taylor, A.G. ; Buchwald, C. ; Landry, M.R.
Title
The biological pump in the Costa Rica Dome: an open-ocean upwelling system with high new production and low export
Type
$loc['typeJournal Article']
Year
2016
Publication
Journal of Plankton Research
Abbreviated Journal
J Plankton Res
Volume
38
Issue
2
Pages
348-365
Keywords
Eastern Tropical Pacific ; biogeochemistry ; carbon flux ; nutrients ; plankton
Abstract
The Costa Rica Dome is a picophytoplankton-dominated, open-ocean upwelling system in the Eastern Tropical Pacific that overlies the ocean's largest oxygen minimum zone. To investigate the efficiency of the biological pump in this unique area, we used shallow (90-150 m) drifting sediment traps and 234Th:238U deficiency measurements to determine export fluxes of carbon, nitrogen and phosphorus in sinking particles. Simultaneous measurements of nitrate uptake and shallow water nitrification allowed us to assess the equilibrium balance of new and export production over a monthly timescale. While f-ratios (new:total production) were reasonably high (0.36 +/- 0.12, mean +/- standard deviation), export efficiencies were considerably lower. Sediment traps suggested e-ratios (export/14C-primary production) at 90-100 m ranging from 0.053 to 0.067. ThE-ratios (234Th disequilibrium-derived export) ranged from 0.038 to 0.088. C:N and N:P stoichiometries of sinking material were both greater than canonical (Redfield) ratios or measured C:N of suspended particulates, and they increased with depth, suggesting that both nitrogen and phosphorus were preferentially remineralized from sinking particles. Our results are consistent with an ecosystem in which mesozooplankton play a major role in energy transfer to higher trophic levels but are relatively inefficient in mediating vertical carbon flux to depth, leading to an imbalance between new production and sinking flux.
Address
Scripps Institution of Oceanography , University of California at San Diego , La Jolla, CA 92037 , 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:27275035; PMCID:PMC4889986
Approved
$loc['no']
Call Number
COAPS @ mfield @
Serial
90
Permanent link to this record
Author
Decima, M. ; Landry, M.R. ; Stukel, M.R. ; Lopez-Lopez, L. ; Krause, J.W.
Title
Mesozooplankton biomass and grazing in the Costa Rica Dome: amplifying variability through the plankton food web
Type
$loc['typeJournal Article']
Year
2016
Publication
Journal of Plankton Research
Abbreviated Journal
J Plankton Res
Volume
38
Issue
2
Pages
317-330
Keywords
Omz ; efficiency ; food chain ; secondary production ; trophic transfer
Abstract
We investigated standing stocks and grazing rates of mesozooplankton assemblages in the Costa Rica Dome (CRD), an open-ocean upwelling ecosystem in the eastern tropical Pacific. While phytoplankton biomass in the CRD is dominated by picophytoplankton (<2-microm cells) with especially high concentrations of Synechococcus spp., we found high mesozooplankton biomass ( approximately 5 g dry weight m-2) and grazing impact (12-50% integrated water column chlorophyll a), indicative of efficient food web transfer from primary producers to higher levels. In contrast to the relative uniformity in water-column chlorophyll a and mesozooplankton biomass, variability in herbivory was substantial, with lower rates in the central dome region and higher rates in areas offset from the dome center. While grazing rates were unrelated to total phytoplankton, correlations with cyanobacteria (negative) and biogenic SiO2 production (positive) suggest that partitioning of primary production among phytoplankton sizes contributes to the variability observed in mesozooplankton metrics. We propose that advection of upwelled waters away from the dome center is accompanied by changes in mesozooplankton composition and grazing rates, reflecting small changes within the primary producers. Small changes within the phytoplankton community resulting in large changes in the mesozooplankton suggest that the variability in lower trophic level dynamics was effectively amplified through the food web.
Address
Dauphin Island Sea Lab , 101 Bienville Blvd, Dauphin Island, AL 36528 , 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:27275033; PMCID:PMC4889985
Approved
$loc['no']
Call Number
COAPS @ mfield @
Serial
75
Permanent link to this record
Author
Krause, J.W. ; Stukel, M.R. ; Taylor, A.G. ; Taniguchi, D.A.A. ; De Verneil, A. ; Landry, M.R.
Title
Net biogenic silica production and the contribution of diatoms to new production and organic matter export in the Costa Rica Dome ecosystem
Type
$loc['typeJournal Article']
Year
2016
Publication
Journal of Plankton Research
Abbreviated Journal
J Plankton Res
Volume
38
Issue
2
Pages
216-229
Keywords
biogenic silica production ; diatom ; new production ; vertical flux
Abstract
We determined the net rate of biogenic silica (bSiO2) production and estimated the diatom contribution to new production and organic matter export in the Costa Rica Dome during summer 2010. The shallow thermocline significantly reduces bSiO2 dissolution rates below the mixed layer, leading to significant enhancement of bSiO2 relative to organic matter (silicate-pump condition). This may explain why deep export of bSiO2 in this region is elevated by an order of magnitude relative to comparable systems. Diatom carbon, relative to autotrophic carbon, was low (<3%); however, the contribution of diatoms to new production averaged 3 and 13% using independent approaches. The 4-old discrepancy between methods may be explained by a low average C:Si ratio ( approximately 1.4) for the net produced diatom C relative to the net produced bSiO2. We speculate that this low production ratio is not the result of reduced C, but may arise from a significant contribution of non-diatom silicifying organisms to bSiO2 production. The contribution of diatoms to organic matter export was minor (5.7%). These results, and those of the broader project, suggest substantial food-web transformation of diatom organic matter in the euphotic zone, which creates enriched bSiO2 relative to organic matter within the exported material.
Address
Scripps Institution of Oceanography , 9500 Gilman Dr., La Jolla, CA 92093-0227 , 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:27275026; PMCID:PMC4889982
Approved
$loc['no']
Call Number
COAPS @ mfield @
Serial
105
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
Permanent link to this record
Author
Stukel, M.R. ; Kahru, M. ; Benitez-Nelson, C.R. ; Décima, M. ; Goericke, R. ; Landry, M.R. ; Ohman, M.D.
Title
Using Lagrangian-based process studies to test satellite algorithms of vertical carbon flux in the eastern North Pacific Ocean
Type
$loc['typeJournal Article']
Year
2015
Publication
Journal of Geophysical Research: Oceans
Abbreviated Journal
J. Geophys. Res. Oceans
Volume
120
Issue
11
Pages
7208-7222
Keywords
satellite-derived export ; carbon export ; model algorithms ; mesozooplankton grazing ; sinking particles ; gravitational flux
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
113
Permanent link to this record