Consider a simple (Lotka–Volterra) model of a prey–predator
system devoid of any spatial effects [90] in which toxic
stress to the predator is introduced analogously to the single
population case in Figure 1 (Fig. 4). In the absence of toxic
effects (t 5 0; Fig. 4a), the predator increases the death of
prey individuals, while the abundance of prey accelerates the
growth of the population of the (successful) predator. As a
consequence of these, both populations show cycling numbers
in time, the predator catching up and controlling the prey
whenever it increases, declining afterwards as a consequence
of prey scarcity. If the predator is under sublethal toxic stress
(t 5 0.05; Fig. 4b), its rate of increase might not be high
enough to control prey increases. The prey population escapes
predator control and grows exponentially until the environment
sets some other limit to its increase (i.e., food–space scarcity,
etc.). At the same time, the abundance of prey produces a
positive effect in the population growth of the predator, which
might compensate the toxic effect. In this case, the prey feeds
the predator but this latter is no longer able to control the prey.