Environmental Engineering Reference
In-Depth Information
14
12
10
8
6
4
2
0
0
5
10
15
20
25
30
# prey species
FIGURE 21.4
Number of piscivorous species as a function of number of prey species from
178 fish assemblages in eastern North America. The dashed line denotes a 1:1 relationship.
Note that more predatory than prey species occur in only one case (after Matthews, 1998).
port mechanisms to acquire and retain useful ions. All fish must regulate
the concentration of ions such as sodium and potassium in order to survive.
Temperature also controls growth, survival, and reproduction of fishes.
At low temperatures, metabolic rates are depressed, and swimming requires
more energy because of the increased viscosity of water (see Chapter 2); an
Reproduction
100
80
Growth
60
40
20
Survival
Survival + growth
Survival + growth + reproduction
0
Environmental gradient
(e.g., salinity, pH, temperature)
FIGURE 21.5
Conceptual illustration of energy requirements for survival, growth, and re-
production as a function of an environmental gradient. If 100% or more of the available en-
ergy is required for survival, the fish will not survive. If the sum of energy required for sur-
vival and growth exceeds 100%, the fish will not grow, and if the sum of energy for survival,
growth, and reproduction is less than 100%, the fish can reproduce.
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