Records
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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$loc['no']
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COAPS @ rl18 @
Serial
978
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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
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0886-6236
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COAPS @ mfield @
Serial
361
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