166
R. A. Ribeiro Filho et al.
absence of true pelagic species, and most of the reservoirs
are populated by species that typically inhabit the coastal
region.
13.1.2 Trophic Cascade Interactions in
Reservoirs
The trophic cascade theory in lakes and reservoirs is based
on two principles: (1) loss of energy between a trophic level
and another and (2) disturbance of a trophic level with consequences in the remaining trophic levels.
The pioneer work of Hrbáček et al. (1961) was responsible for highlighting the effect of fish on the structure of
the aquatic food chain. After a few years, research such as
Brooks and Dodson (1965) and Shapiro et al. (1975) contributed to the development of the food web theory in lakes,
revealing the important role of fish, ignored for decades in
the field of limnology.
The first book that dealt with the cascade effect in lakes
was “The trophic cascade in lakes” (Carpenter and Kitchell 1993). In this work the authors discuss topics such as:
trophic cascade interactions, fish behavior in response to
manipulation, the dynamics of phytoplankton and zooplankton, interaction between primary productivity and nutrients,
simulation models of trophic cascade, among others, being
of great importance to understanding how trophic cascade
effects work in aquatic ecosystems.
The theory of trophic cascades (Carpenter and Kitchell
1993; see critiques from Demelo et al. 1992; and the metaanalyses of Brett and Goldman 1996, 1997) and the bottomup/top-down theory (Mcqueen et al. 1986) are the two main
conceptual models of work used here. Phytoplankton responds positively to nutrient-enriched systems with an odd
number of trophic levels (three levels: phytoplankton, zooplankton, and planktivorous fish), but not in systems with an
even number of trophic levels (two levels without fishes, or
four levels with piscivorous fishes).
The effect of the stock of planktivorous fish on the zooplankton community has been well-studied (Arcifa et al.
1986; Lazzaro 1987; Lazzaro 1991) and there is strong pressure of these fish on the biomass of algae (Pijanowska and
Prejs 1997; Jeppesen et al. 1997). The effect of piscivorous
fishes in a system has a strong relationship with the stock
of planktivorous fishes, causing the drastic reduction of latter (Mcqueen 1990; Demelo et al. 1992; Hambright 1994).
Some studies confirm that the impact of fish stocks favors
the concentrations of chlorophyll through the excretion of
nutrients and the predation of zooplankton (Mcqueen et al.
1992; Lazzaro 1997; Drenner 1998; Starling 1998). With regard to the stock of piscivorous fishes, many studies were not
successful (Demello et al. 1992; Mcqueen et al. 1992), mainly owing to the low stocking density (Perrow et al. 1997).
In many studies the top-down effect was observed (Shapiro
et al. 1975; Shapiro and Wright 1984; Carpenter et al. 1985;
Persson et al. 1988; Mcqueen, 1990; Faafeng and Brabrand
1990; Carpenter and Kitchell 1993; Pijanowska and Prejs
1997; Sondergaard et al. 1997; Prejs et al. 1997; Meijer et al.
1999).
Carpenter et al. (1985) suggest that knowing how the food
chain works can be useful for the management of aquatic
ecosystems aiming at ecology conservation. The increase of
piscivorous fishes may decrease the density of planktivorous
ones and, consequently, increase grazing and depletions in
the concentrations of chlorophyll-a. The increase in the stock
of piscivores can be a tool for rehabilitating eutrophic lakes.
The concept of trophic cascade with links between limnology and fisheries biology suggests a biological alternative
for lake management.
Studies by Brett and Goldman (1996) prove the theory
of trophic cascade. They noted that the manipulation of fish
communities can be used to control algal biomass, but these
relationships are fragile. The authors mention that the control of the phytoplankton through the trophic cascade management (biomanipulation) can be successful in about 60 %
of the cases and that the reduction zooplanktivorous species
would result in a slight reduction in phytoplankton biomass
and hence a small improvement in the quality of water.
Borer et al. (2005) tested the trophic cascade hypothesis
using a review of 114 studies with tested indirect trophic
relations. The biomass of predators had a direct effect on
plant biomass, both in terrestrial and aquatic environments.
A combination of herbivory and metabolic and taxonomic
factors of predation explained 31 % of the cascade relationships among all 114 studies. Within systems, 18 % of the cascade relationship was explained owing to the predators that
have similar characteristics to herbivores. In all systems, the
strongest cascades occurred in invertebrate herbivores and
endothermic vertebrate predators associations. These associations are derived from a combination of real biological
differences among species with different physiological requirements, and the influence of organisms studied in different systems.
Benndorf et al. (2002) mention that the top-down control of chlorophyll-a occurs according to the following conditions: (i) short-term experiments, (ii) shallow lakes with
macrophytes and (iii) deep slightly eutrophic or mesotrophic
lakes. Other experiments indicate that top-down control may
be unlikely in the following conditions: (iv) eutrophic or
hypertrophic deep lakes, unless there is severe limitation of
light, and (v) for all lakes when there is extreme nutrient limitation (oligotrophic and ultraoligotrophic lakes). Important
factors that are responsible for the top-down control under
the described conditions in (i) and (iii) are the time scales
that prevent the slow development of phytoplankton; shallow depths allow macrophytes to become dominant primary
R. A. Ribeiro Filho et al.
absence of true pelagic species, and most of the reservoirs
are populated by species that typically inhabit the coastal
region.
13.1.2 Trophic Cascade Interactions in
Reservoirs
The trophic cascade theory in lakes and reservoirs is based
on two principles: (1) loss of energy between a trophic level
and another and (2) disturbance of a trophic level with consequences in the remaining trophic levels.
The pioneer work of Hrbáček et al. (1961) was responsible for highlighting the effect of fish on the structure of
the aquatic food chain. After a few years, research such as
Brooks and Dodson (1965) and Shapiro et al. (1975) contributed to the development of the food web theory in lakes,
revealing the important role of fish, ignored for decades in
the field of limnology.
The first book that dealt with the cascade effect in lakes
was “The trophic cascade in lakes” (Carpenter and Kitchell 1993). In this work the authors discuss topics such as:
trophic cascade interactions, fish behavior in response to
manipulation, the dynamics of phytoplankton and zooplankton, interaction between primary productivity and nutrients,
simulation models of trophic cascade, among others, being
of great importance to understanding how trophic cascade
effects work in aquatic ecosystems.
The theory of trophic cascades (Carpenter and Kitchell
1993; see critiques from Demelo et al. 1992; and the metaanalyses of Brett and Goldman 1996, 1997) and the bottomup/top-down theory (Mcqueen et al. 1986) are the two main
conceptual models of work used here. Phytoplankton responds positively to nutrient-enriched systems with an odd
number of trophic levels (three levels: phytoplankton, zooplankton, and planktivorous fish), but not in systems with an
even number of trophic levels (two levels without fishes, or
four levels with piscivorous fishes).
The effect of the stock of planktivorous fish on the zooplankton community has been well-studied (Arcifa et al.
1986; Lazzaro 1987; Lazzaro 1991) and there is strong pressure of these fish on the biomass of algae (Pijanowska and
Prejs 1997; Jeppesen et al. 1997). The effect of piscivorous
fishes in a system has a strong relationship with the stock
of planktivorous fishes, causing the drastic reduction of latter (Mcqueen 1990; Demelo et al. 1992; Hambright 1994).
Some studies confirm that the impact of fish stocks favors
the concentrations of chlorophyll through the excretion of
nutrients and the predation of zooplankton (Mcqueen et al.
1992; Lazzaro 1997; Drenner 1998; Starling 1998). With regard to the stock of piscivorous fishes, many studies were not
successful (Demello et al. 1992; Mcqueen et al. 1992), mainly owing to the low stocking density (Perrow et al. 1997).
In many studies the top-down effect was observed (Shapiro
et al. 1975; Shapiro and Wright 1984; Carpenter et al. 1985;
Persson et al. 1988; Mcqueen, 1990; Faafeng and Brabrand
1990; Carpenter and Kitchell 1993; Pijanowska and Prejs
1997; Sondergaard et al. 1997; Prejs et al. 1997; Meijer et al.
1999).
Carpenter et al. (1985) suggest that knowing how the food
chain works can be useful for the management of aquatic
ecosystems aiming at ecology conservation. The increase of
piscivorous fishes may decrease the density of planktivorous
ones and, consequently, increase grazing and depletions in
the concentrations of chlorophyll-a. The increase in the stock
of piscivores can be a tool for rehabilitating eutrophic lakes.
The concept of trophic cascade with links between limnology and fisheries biology suggests a biological alternative
for lake management.
Studies by Brett and Goldman (1996) prove the theory
of trophic cascade. They noted that the manipulation of fish
communities can be used to control algal biomass, but these
relationships are fragile. The authors mention that the control of the phytoplankton through the trophic cascade management (biomanipulation) can be successful in about 60 %
of the cases and that the reduction zooplanktivorous species
would result in a slight reduction in phytoplankton biomass
and hence a small improvement in the quality of water.
Borer et al. (2005) tested the trophic cascade hypothesis
using a review of 114 studies with tested indirect trophic
relations. The biomass of predators had a direct effect on
plant biomass, both in terrestrial and aquatic environments.
A combination of herbivory and metabolic and taxonomic
factors of predation explained 31 % of the cascade relationships among all 114 studies. Within systems, 18 % of the cascade relationship was explained owing to the predators that
have similar characteristics to herbivores. In all systems, the
strongest cascades occurred in invertebrate herbivores and
endothermic vertebrate predators associations. These associations are derived from a combination of real biological
differences among species with different physiological requirements, and the influence of organisms studied in different systems.
Benndorf et al. (2002) mention that the top-down control of chlorophyll-a occurs according to the following conditions: (i) short-term experiments, (ii) shallow lakes with
macrophytes and (iii) deep slightly eutrophic or mesotrophic
lakes. Other experiments indicate that top-down control may
be unlikely in the following conditions: (iv) eutrophic or
hypertrophic deep lakes, unless there is severe limitation of
light, and (v) for all lakes when there is extreme nutrient limitation (oligotrophic and ultraoligotrophic lakes). Important
factors that are responsible for the top-down control under
the described conditions in (i) and (iii) are the time scales
that prevent the slow development of phytoplankton; shallow depths allow macrophytes to become dominant primary