PCWA-L 480.pdf - PCWA Middle Fork American River Project ...

.Core Processes in Bioenergetics
Equation 2: Temperature dependent with activity mUltiplier
(Kitchell et a!. 1977)
'f(T) == V X . e(x'(l-V»
ACTIVITY == ACT
. where:
v == (RTM - T) 1(RTM - RTO)
X == (Z2 . (1 + (1 +401 y)os)') 1400
Z = LN(RQ)· (RTM -RTO)
Y == LN(RQ)· (RTM - RTO -+ 2)
With this formulation, the temperature dependence of respiration is adjusted by an activity
mUltiplier (ACT). RTO (' C) is the optimum temperature for respiration (where respiration is.
highest), RTM (. C) is the maximum (Iethai) water temperature, and RQ (. C') approximates the
0 10 (the rate at which the function Increases over reiatlvely low water temperatures). For .
computing R",,,, RA is the number of grams of oxygen (g.g" d") consumed by a 1 gram fish at
RTO and RS is the slope of the allometric mass function for standard metabolism: Activity (ACT)
is a constant times resting metabolism, the "Winberg mUitlplier" (Winberg 1956). Several recent
studies have shown that activity may be a large and variable component of the total energy budget
and Is influenced by a number of enVironmental and physiological factors (Boisclair and Leggett
1989, Boisciair and Sirois 199'3, Lucas eta1.1993, Madon and Culver 1993).
2.3 Waste Losses (Egestion and. Excretion)
Egestion (fecal waste, F) and excretion (nitrogenous waste, V) can be computed as a constant
proportion of consumption, or as functions of water temperature and consumption. Waste losses
are computed as grams of waste per gram of fish'per day.
Equation Set 1: .Proportional to consumption (Kitchell et at: .'
1977)' .
Egestlon:
Excretion:
F== FA·C
U==UA·(C-F)
Egestion Is a constant proportion (FA) of consumption. Excretion is a constant proportion (VA) of
assimilated energy (consumption minus egestion). This formulation suffices for most species.
Equation Set 2: Dependent on mass, temperature and ration
(Elliott 1976)
Egestion: F == FA· T FB • e(FG.p) . C
Excretion: U == UA· TUB . e(UG.p) .(C- F)
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,.'.