10
The Eutrophication Problem in Temperate Lakes: Practical Aspects and Theoratical ...
1.4 Scope and Strategy
Many of the central issues in lake management and eutrophication control
appear to be deeply related to key research fields in ecological theory, such
as resource competition, food web structure, and nutrient cycling. Likewise, the problem of controlling algal blooms by food web manipulations is
essentially a question of maintaining the stability and persistence of an
enriched prey-predator system. Nevertheless, the exchange of ideas
between the fields of lake management and ecological theory appears to
have been limited.
This lack of communication might be related to the traditional dichotomy that has separated ecologists into those following the populationcommunity approach and those that follow the process-functional
approach (sensu DeAngelis 1990). The first approach, which might be
called evolutionary, or species-oriented, focuses on the dynamics of population interactions and the patterns of trophic connections. The second
approach, which also can be called flow-oriented or biogeochemical,
focuses on the energy and material cycles of ecological systems. While
researchers in theoretical ecology have typically been trained in the species-oriented school, researchers working with eutrophication problems
have typically been recruited from the flow-oriented school.
Although these two points of view seem to have coexisted in the origins of
ecological theory (e.g., Lotka 1925), it is only recently that attempts have been
made to reunite them. DeAngelis (1990) points out that food web dynamics
and biogeochemistry are deeply interrelated in the sense that while food webs
are influenced by limitations of energy and matter, the interactions among
species populations within food webs may themselves influence energy flow
and material cycling. The present work is an attempt to follow the direction
staked out by DeAngelis (1990), by merging some well-established ideas from
static nutrient loading models with a dynamic view of pelagic nutrient
cycling, and analyzing the resulting models using techniques and principles
from the ecological theories of predation and competition.
Time and space constraints exclude treating all aspects of pelagic nutrient cycling in a work like this. By limiting the scope to lakes where planktivorous fish are expected to have minor impact on zooplankton dynamics, a
focus on the first two levels of the food web can be defended. This means
that the models will primarily apply to lakes where fish are absent either
due to food web manipulations or for biogeographic reasons, or where
planktivore populations are under strong control by piscivorous fish.
The model development will take a minimalistic approach, implying that
simplicity will sometimes be chosen at the price of generality and biological
realism. Model analysis will emphasize qualitative dynamical concepts like
stability, periodic orbits, persistence, coexistence, and exclusion. Model
predictions will be compared with synoptic data on variability among
The Eutrophication Problem in Temperate Lakes: Practical Aspects and Theoratical ...
1.4 Scope and Strategy
Many of the central issues in lake management and eutrophication control
appear to be deeply related to key research fields in ecological theory, such
as resource competition, food web structure, and nutrient cycling. Likewise, the problem of controlling algal blooms by food web manipulations is
essentially a question of maintaining the stability and persistence of an
enriched prey-predator system. Nevertheless, the exchange of ideas
between the fields of lake management and ecological theory appears to
have been limited.
This lack of communication might be related to the traditional dichotomy that has separated ecologists into those following the populationcommunity approach and those that follow the process-functional
approach (sensu DeAngelis 1990). The first approach, which might be
called evolutionary, or species-oriented, focuses on the dynamics of population interactions and the patterns of trophic connections. The second
approach, which also can be called flow-oriented or biogeochemical,
focuses on the energy and material cycles of ecological systems. While
researchers in theoretical ecology have typically been trained in the species-oriented school, researchers working with eutrophication problems
have typically been recruited from the flow-oriented school.
Although these two points of view seem to have coexisted in the origins of
ecological theory (e.g., Lotka 1925), it is only recently that attempts have been
made to reunite them. DeAngelis (1990) points out that food web dynamics
and biogeochemistry are deeply interrelated in the sense that while food webs
are influenced by limitations of energy and matter, the interactions among
species populations within food webs may themselves influence energy flow
and material cycling. The present work is an attempt to follow the direction
staked out by DeAngelis (1990), by merging some well-established ideas from
static nutrient loading models with a dynamic view of pelagic nutrient
cycling, and analyzing the resulting models using techniques and principles
from the ecological theories of predation and competition.
Time and space constraints exclude treating all aspects of pelagic nutrient cycling in a work like this. By limiting the scope to lakes where planktivorous fish are expected to have minor impact on zooplankton dynamics, a
focus on the first two levels of the food web can be defended. This means
that the models will primarily apply to lakes where fish are absent either
due to food web manipulations or for biogeographic reasons, or where
planktivore populations are under strong control by piscivorous fish.
The model development will take a minimalistic approach, implying that
simplicity will sometimes be chosen at the price of generality and biological
realism. Model analysis will emphasize qualitative dynamical concepts like
stability, periodic orbits, persistence, coexistence, and exclusion. Model
predictions will be compared with synoptic data on variability among