80
Herbivores and Algae: Food Utilization, Growth and Reproduction ...
Lampert and coworkers have used a flow-through system (Lampert
1976) for growing food-limited zooplankton under controlled conditions.
The combination of high flow rate and a gradual reduction of the number
of animals per culture chamber as they grow makes it possible to keep
zooplankton at a constant food concentration throughout their lives. For
solutions of the model [Eq. (4.9)] with the functional response given by Eq.
(4.11), an incipient limiting food level C' = 0.17 (mg C) r
1 gave the best fit to
a published set of growth curves by Taylor (1985). Figure 4.8 indicates that
a constant C', independent of body size, is sufficient to describe foodlimited growth in Daphnia pulex. The use of a piecewise linear functional
response in Eq. (4.11), implying exactly overlapping growth curves for all
food levels C > C', finds some support in Taylor (1985), who observed
nearly identical growth curves in Daphnia pulex at 0.5 and 1.0 (mg C) r1.
60
G 40
bO
::t
'-"
Q)
N
.~
CI)
oS o 20
~
o
o
10
20
Age (d)
+
f
--0.1 mg C liter- 1
30
-1
Fig. 4.8. Simulated body growth in Daphnia pulex at constant food concentrations of 1.0 (mg C) I
(upper curve) and 0.1 (mg C) r1 (lower curve). Vertical bars and squares are ranges and medians of
observations from Daphnia pulex grown in flow-trough cultures at the same food levels (Taylor
1985), recalculated to carbon units using Eq. (4.5)
Herbivores and Algae: Food Utilization, Growth and Reproduction ...
Lampert and coworkers have used a flow-through system (Lampert
1976) for growing food-limited zooplankton under controlled conditions.
The combination of high flow rate and a gradual reduction of the number
of animals per culture chamber as they grow makes it possible to keep
zooplankton at a constant food concentration throughout their lives. For
solutions of the model [Eq. (4.9)] with the functional response given by Eq.
(4.11), an incipient limiting food level C' = 0.17 (mg C) r
1 gave the best fit to
a published set of growth curves by Taylor (1985). Figure 4.8 indicates that
a constant C', independent of body size, is sufficient to describe foodlimited growth in Daphnia pulex. The use of a piecewise linear functional
response in Eq. (4.11), implying exactly overlapping growth curves for all
food levels C > C', finds some support in Taylor (1985), who observed
nearly identical growth curves in Daphnia pulex at 0.5 and 1.0 (mg C) r1.
60
G 40
bO
::t
'-"
Q)
N
.~
CI)
oS o 20
~
o
o
10
20
Age (d)
+
f
--0.1 mg C liter- 1
30
-1
Fig. 4.8. Simulated body growth in Daphnia pulex at constant food concentrations of 1.0 (mg C) I
(upper curve) and 0.1 (mg C) r1 (lower curve). Vertical bars and squares are ranges and medians of
observations from Daphnia pulex grown in flow-trough cultures at the same food levels (Taylor
1985), recalculated to carbon units using Eq. (4.5)