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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
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Author Wang, S.; Kranz, S.A.; Kelly, T.B.; Song, H.; Stukel, M.R.; Cassar, N.
Title Lagrangian Studies of Net Community Production: The Effect of Diel and Multiday Nonsteady State Factors and Vertical Fluxes on O2/Ar in a Dynamic Upwelling Region Type $loc['typeJournal Article']
Year 2020 Publication Journal of Geophysical Research: Biogeosciences Abbreviated Journal J. Geophys. Res. Biogeosci.
Volume 125 Issue 6 Pages e2019JG005569
Keywords net community production; O2/Ar; California Current Ecosystem; Lagrangian measurements; vertical fluxes; nonsteady state
Abstract The ratio of dissolved oxygen to argon in seawater is frequently employed to estimate rates of net community production (NCP) in the oceanic mixed layer. The in situ O2/Ar&#8208;based method accounts for many physical factors that influence oxygen concentrations, permitting isolation of the biological oxygen signal produced by the balance of photosynthesis and respiration. However, this technique traditionally relies upon several assumptions when calculating the mixed&#8208;layer O2/Ar budget, most notably the absence of vertical fluxes of O2/Ar and the principle that the air&#8208;sea gas exchange of biological oxygen closely approximates net productivity rates. Employing a Lagrangian study design and leveraging data outputs from a regional physical oceanographic model, we conducted in situ measurements of O2/Ar in the California Current Ecosystem in spring 2016 and summer 2017 to evaluate these assumptions within a &#65533;worst&#8208;case&#65533; field environment. Quantifying vertical fluxes, incorporating nonsteady state changes in O2/Ar, and comparing NCP estimates evaluated over several day versus longer timescales, we find differences in NCP metrics calculated over different time intervals to be considerable, also observing significant potential effects from vertical fluxes, particularly advection. Additionally, we observe strong diel variability in O2/Ar and NCP rates at multiple stations. Our results reemphasize the importance of accounting for vertical fluxes when interpreting O2/Ar&#8208;derived NCP data and the potentially large effect of nonsteady state conditions on NCP evaluated over shorter timescales. In addition, diel cycles in surface O2/Ar can also bias interpretation of NCP data based on local productivity and the time of day when measurements were made.
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 2169-8953 ISBN Medium
Area Expedition Conference
Funding Approved $loc['no']
Call Number COAPS @ user @ Serial 1114
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