Spatial and temporal patterns of growth and consumption by juvenile spring/summer Chinook salmonOncorhynchus tshawytscha.

P. M. Chittaro1, R. W. Zabel, K. Haught, B.L. Sanderson and B.P. Kennedy

Paul M. Chittaro: Fish Ecology Division, Northwest Fisheries Science Center, National Marine Fisheries, National Oceanic and Atmospheric Administration, 2725 Montlake Blvd. E., Seattle, WA 98112, USA.

Richard W. Zabel: Fish Ecology Division, Northwest Fisheries Science Center, National Marine Fisheries, National Oceanic and Atmospheric Administration, 2725 Montlake Blvd. E., Seattle, WA 98112, USA.

Kerri Haught: Fish Ecology Division, Northwest Fisheries Science Center, National Marine Fisheries, National Oceanic and Atmospheric Administration, 2725 Montlake Blvd. E., Seattle, WA 98112, USA.

Beth L. Sanderson: Northwest Fisheries Science Center, 2725 Montlake Blvd. E., Seattle, WA, 98112, USA.

Brian P. Kennedy: Department of Fish and Wildlife Resources, University of Idaho, Moscow, ID, 83844, USA.

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1email:

Online Resource Table 1. Invertebrate taxa (and invertebrate groups) found in O. tshawytschadiets (data obtained from gut contents analysis) and their respective energy densities (J g-1 wet weight) (obtained from the literature).

Invertebrate group / Taxa / Energy density (J g-1)
Diptera
(3841.43+/-778.42 J g-1) / Chironomidae (larva) / 4591.70 (3500.00)
Simuliidae / 3184.55
Tipulidae / 4669.09
Ceratopogonidae / 3596
Other Diptera + Simulidae larva / 4602.68
Other Diptera larva / 2746.02
Ephemeroptera
(4104.70+/-845.26J g-1) / Baetidae / 4551.272
Leptophlebiidae / 4342.992
Heptageniidae / 4674.365
Ephemerellidae / 3065.826
Other Ephemeroptera (emerging) (adult) / 3716 (4837.92) (4535.51)
Plecoptera / Plecoptera / 4455.76
Trichoptera
(4317.29+/-363.05 J g-1) / Hyrdopsychidae / 4507.005
Limnephilidae / 4034.611
Other Trichoptera (brachycentridae, lepidostomatidae, glossomatidae, rhyacophilidae) / 4853.44
Trichoptera; emerging, adult / 4208.97, 3982.44
Ceoleoptera/Hemiptera
(4756.83+/-294.56 J g-1) / Elmidae larvae / 4434.15
Collembola / 4769.17
Other aquatic beetle larva / 5144.24
Aquatic Hemiptera adult / 4679.746
Gastropoda and other taxa
(3939.32+/-1036.16 J g-1) / Oligochaete / 4620.87
Nematode / 3675.08
Mite / 4863.62
Snail / 814.27
Ostracod / 2585.7
Copepod / 3035.35
Cladocera / 4165.9
Terrestrial taxa
(4263.72+/-497.05 J g-1) / Homoptera—hopper, aphid / 4721.26
Diptera / 4533.7
Lepidoptera / 4567.78
Hemiptera / 3581.00
Psocoptera / 4567.18
Coleoptera—Beetle (larva) / 3606.61 (5144.24)
Hymenoptera—ant, wasp / 3649.32, 4928.85
Thysanoptera—Thrips / 4383.78
Orthoptera—Grasshopper / 4435.04
Spider / 4331.70
Other terrestrial insects / 4500
Unknown larva / 3876.32

Online Resource Table2. Parameter values for the equations (see below) of the O. tshawytschabioenergetics modeltaken from Hanson et al.(1997).

Symbol / Parameter description / Value
Consumption
CA / Intercept of allometric mass function (gg-1d-1) / 0.303
CB / Slope of allometric mass function / -0.275
CQ / Water temp. for G1 (C) / 5
CTO / Water temp. for G1 (C) / 15
CTM / Water temp. for G2 (C) / 18
CTL / Water temp. for G2 (C) / 24
CK1 / Proportion of Cmax for KA / 0.36
CK4 / Proportion of Cmax for KB / 0.01
G1 / G1 = (1 / (CTO - CQ)) * ln (( 0.98 * (1 - CK1)) / (CK1 * 0.02)) / 0.527418
G2 / G2 = (1 / (CTL - CTM)) * ln (( 0.98 * (1 - CK4)) / (CK4 * 0.02)) / 1.472394
Respiration
RA / Intercept of allometric mass function (g of O2g-1d-1) / 0.00264
RB / Slope of allometric mass function / -0.217
RQ / Rate at which the function increases over low water temp. (approximates Q10) / 0.06818
RTO / Coefficient of swimming speed dependence on metabolism (scm-1) / 0.0234
RTM / Constant / 0
RTL / Cutoff temp. at which the activity relationship changes (C) / 25
RK1 / Intercept of the swimming speed above the cutoff temp. (cms-1) / 1
RK4 / Mass dependent coefficient for swimming speed at all temp. / 0.13
ACT / Activity multiplier is the intercept of the relationship between swimming speed and mass at water temp. < RTL (cm/s for 1 g fish at 0C) / 9.7
BACT / Water temp. dependence coefficient of swimming speed at temp. < RTL (C) / 0.0405
SDA / Proportion of energy lost to specific dynamic action / 0.172
OXY / Oxycalorific coefficient (taken from Elliot 1976) (calg-1 of O2) / 3240
THER / Thermo constant (calJ-1) / 0.239006
Egestion & Excretion
FA / Intercept of the proportion of consumed energy egested vs. water temp. & ration / 0.212
FB / Coefficient of temp. dependence of egestion / -0.222
FG / Coefficient of feeding level dependence of egestion / 0.631
UA / Intercept of the proportion of consumed energy excreted vs. water temp. & ration / 0.0314
UB / Coefficient of temp.dependence of excretion / 0.58
UG / Coefficient of feeding level dependence of excretion / -0.299
Predator Energy Density
Alpha / Intercept of the allometric mass function (Jg-1) / 7602
Beta / Slope of the allometric mass function / 0.5266

Online Resource 1- Bioenergetics model equations:

Consumption (C) is the mass-specific consumption rate (gg-1d-1) and is defined as,

C = P * Cmax * f (T),

where P is the proportion of maximum consumption necessary to obtain simulated growth, Cmax is the maximum mass-specific feeding rate (gg-1d-1), which is defined as,

Cmax = CA * WCB,

where W is fish mass (g).f(T) is the temperature dependence of consumption function (Kitchell et al. 1977; Table A2), defined as,

f(T) = KA * KB,

where T is water temperature(C),KA is the increasing portion of the temperature dependent equation,

KA = (CK1 * L1) / (1 + CK1 * (L1 - 1)); L1 = e (G1 * (T-CQ)),

and KBis the decreasing portion of the temperature dependent equation,

KB = (CK4 * L2) / (1 + CK4 * (L2 -1)); L2 = e (G2 * (CTL - T)),

Respiration (R) is themass-specific rate of respiration (gg-1d-1), and is defined as,

R = RA * WRB * f(T) * ACTIVITY * (OXY/THER),

where an exponential relationship describes the temperature dependence of metabolism and activity as a function of swimming speed (Stewart et al. 1983; see Table A2), such that,

f(T) = e(RQ * T),

ACTIVITY = e(RTO * VEL),

VEL = ACT * WRK4 * e(BACT * T), when T ≤ RTL,

and S is the proportion of energy lost to specific dynamic action (Jg-1),

S = SDA * (C - F),

Waste losses are modeled via egestion and excretion equations. Egestion (F) is the waste attributed to fecal loss (J/g) and excretion (U) is the waste attributed to nitrogenous loss (Jg-1), such that

F = PF * C, and

U = UA * TUB * e(UG * p) * (C - F),

respectively. PF and PE correct for indigestible prey (see Stewart et al. 1983). PF is the proportion of egested prey, PFF is the proportion of prey that is indigestible (which we set to 0.1), and PE is the proportion of consumption that was egested prey.

PF = ((PE - 0.1) / 0.9)*(1-PFF) + PFF,

PE = FA * TFB * e(FG * p),

Predator energy density (ED; J/g) was defined as

ED = Alpha + (Beta * W) (see Table A2).

Next we estimated the amount of surplus energy (E; per gram of fish) available for growth (Jg1), such that

E = C – R – S – F – U,

and the estimated fish size (EFS; g)

EFS= W + (E * (W / E)).

The difference between the estimated fish size from the bioenergetics model and fish size determined from otolith microstructural analyses was minimized in R by changing values of the proportion of maximum consumption (P).

Online Resource Figure 1. Proportion of prey invertebrate groups in the diet of O. tshawytschacollected in July and September 2004, from each of four rearing streams; a) SFS, b) ELK, c) MAR, and d) VAL (see Table SI for invertebrate taxa associated with each group). Proportion of diet was calculated from averages across individuals within a stream collected in July or September (see Table 1 for sample sizes).