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2
3
Supporting Information
Ten parameters of the model are not constrained by direct measurements or mass balance: the growth
4
efficiencies gAZ and gTZ, the half-saturation coefficients h and hF, the egestion fractions pA, pD and pT, and
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the sedimentation rates sA, sD and sT. These parameters were estimated from literature values as explained
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in the main text. These ten parameters could potentially affect the four derived quantities that were
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calculated by the model and not directly measured: the flux of zooplankton to planktivory cF, steady-state
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biomass of detritus derived from phytoplankton D*, growth efficiency of zooplankton on TPOC gTZ, and
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the supply rate of TPOC available to zooplankton IT.
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To evaluate the effect of the ten parameters estimated from the literature on the four derived quantities
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that were not directly measured, we computed the effect of a 1% increase of each parameter on the four
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derived quantities (Table SI.1).
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In most cases the change in the derived quantity was less than 1%, indicating that any errors in parameters
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estimated from the literature are not amplified by the model; rather their effects on the derived quantities
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are decreased by the model. Only three responses were greater than 1%. A 1% increase in the growth
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efficiency of zooplankton feeding on phytoplankton, gAZ, causes a 1.16% increase in planktivory,
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indicating that the increased growth of zooplankton must be passed to planktivores in order to satisfy
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mass balance. A 1% increase in the half-saturation coefficient for planktivory hF causes a nearly 2%
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increase in the flux of zooplankton biomass to zooplankton. However, a larger change in hF would have a
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constrained effect on planktivory because of the sigmoid shape of the planktivory function. A 1% increase
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in the egestion fraction for phytoplankton, pA, causes a 1% increase biomass of detritus derived from
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phytoplankton.
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Finally we note that a 1% increase in the egestion fraction for TPOC, pT, causes a decrease in the supply
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rate of TPOC by 0.84%. With a higher egestion fraction, the observed TPOC concentration can be met by
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a smaller supply rate, according to mass balance.
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30
31
32
33
34
35
36
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Table SI.1. Responses (%) of four derived quantities that were not directly measured (flux of zooplankton
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to planktivory cF, steady-state biomass of detritus derived from phytoplankton D*, growth efficiency of
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zooplankton on TPOC gTZ, and the supply rate of TPOC available to zooplankton IT) to 1% increases in
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the 10 parameters that were estimated from literature and not directly measured (growth efficiencies gAZ
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and gTZ, the half-saturation coefficients h and hF, the egestion fractions pA, pD and pT, and the
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sedimentation rates sA, sD and sT).
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Parameter increased by 1%
gAZ
gDZ
h
hF
pA
pD
pT
sA
sD
sT
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45
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% Change in Model Derived Quantity
cF
D*
gTZ
IT
1.15
0
0.95
0
0.06
0
0.05
0
0
0
0
0
1.99
0
0
0
0.06
1.00
0.05
0
0.02
0.26
0.01
0
0
0
0
-0.84
-0.34
-0.11
-0.01
-0.23
-0.02
-0.40
-0.02
0
0
0
0
0.16