56
M. Callisto et al.
macroinvertebrate communities have frequently been used
in assessments of human impacts on freshwater (Rosenberg
1992; Junqueira et al. 2000; Brooks et al. 2001; Fleituch
et al. 2002). The use of bioindicators to assess water quality
is based on the response of the organisms to changes in their
environment, including perturbations of human or natural
origins, and reflects their lifestyle and sedimentary behavior
(Bonada et al. 2006).
There are many benefits of using benthic macroinvertebrates for biomonitoring programs: (a) they are easily collected and identified at the family or genera levels; (b) many
taxa are sedentary and possess long life cycles, making them
capable of registering cumulative effects on their habitats,
and (c) they are sensitive to physical and chemical changes
in ecosystems, and their responses to these alterations are
detectable and measurable (Barbour et al. 1996).
There are a variety of benthic organisms that are frequently highly abundant in reservoirs; these organisms include Chironomidae, Oligochaeta, Bivalvia, Hirudinea,
and Chaoboridae (Takeda et al. 1990; Brooks et al. 2001;
Martins-Montanholi and Takeda 2001; Santos et al. 2006).
Chironomidae larvae exhibit a high diversity of ecological
features and are capable of surviving in many different environmental conditions, where some species are tolerant or
sensitive to low oxygen concentrations, extremes of temperature, pH, salinity, and trophy (Prat et al. 1992; Henry 1993;
Cranston 1995).
5.2 Basic Concepts
5.2.1 Lake Aging
Lake aging is a natural process that occurs on a geologic
timescale and results in the lake being filled with materials that are eroded and transported by tributaries, deposited
from the atmosphere and produced in the lake. Differences in
runoff and watershed characteristics cause lakes to fill-in at
different rates. The didactic natural succession is from lake
to pond, pond to marsh, marsh to meadow, and meadow to
dry land.
5.2.2 Brazilian Lacustrine Ecosystems
In Brazil, most lacustrine ecosystems are characterized as
lagoons owing to their geomorphological origin related to
the meanders of large rivers, coastal lagoons near the sea
in the “restinga” formation, or in the floodplains of Amazonia and the Pantanal. Some deep lakes can be found in the
Minas Gerais State in southeastern Brazil that originated in
the curves of the Doce River (Barbosa et al. 1999).
5.2.3 Anthropogenic (Cultural) Eutrophication
Human land use, deforestation, and untreated sewage disposal are common causes of eutrophication in freshwater.
Originally, eutrophication was known as the increased productivity of a lake as it ages. Often, an increased nutrient
supply from human activities results in an increase in the
biological production of the lake. Although the increased
production may increase the rate of lake filling, it is incorrect to define eutrophication as lake aging. A lake does not
die when it reaches a state of high productivity, but rather
when it has been completely filled in and no longer exists.
Lake filling results from production that occurs within the
lake, which may increase with eutrophication, and from the
deposition of organic and inorganic materials from outside
the lake, which is not related to lake eutrophication.
5.3 Too Much of a Good Thing
Natural eutrophication is a fairly slow and gradual process
that typically occurs over a period of many centuries as natural disturbances cause an imbalance between production and
consumption within the lake, and the lake slowly becomes
overfertilized. Although natural eutrophication is not rare
in nature, it does not occur frequently or quickly. However,
cultural eutrophication has become so common that the word
“eutrophication” has come to mean a very harmful increase
and acceleration of nutrient concentrations within a water
body. The situation is as if something receives too much fertilizer or has too much of a good thing.
5.3.1 What is Meant by Trophic State?
In temperate regions, the term “trophic” originally referred
to the nutrient status of an ecosystem. Esteves (1988) discussed the misuse of the lake typology approach in tropical regions and argued that it is necessary to consider the
naturally high nutrient concentrations in tropical lakes. His
paper, titled “Considerations on the application of typology
of temperate lakes to tropical lakes,” stressed the inadequacy
of its application. The metabolic patterns of tropical lakes are
completely different than temperate lacustrine ecosystems.
When the basic indicators used in the typology of temperate
lakes are applied to tropical lakes, the resulting classification
may cause the same ecosystem to be placed into different
categories.
Thienemann (1913) was the first author to use the distribution of benthic chironomid larva to classify lakes in Germany and, later, to propose his typology. In his studies of
volcanic lakes in the Eifel region, he discovered a different
M. Callisto et al.
macroinvertebrate communities have frequently been used
in assessments of human impacts on freshwater (Rosenberg
1992; Junqueira et al. 2000; Brooks et al. 2001; Fleituch
et al. 2002). The use of bioindicators to assess water quality
is based on the response of the organisms to changes in their
environment, including perturbations of human or natural
origins, and reflects their lifestyle and sedimentary behavior
(Bonada et al. 2006).
There are many benefits of using benthic macroinvertebrates for biomonitoring programs: (a) they are easily collected and identified at the family or genera levels; (b) many
taxa are sedentary and possess long life cycles, making them
capable of registering cumulative effects on their habitats,
and (c) they are sensitive to physical and chemical changes
in ecosystems, and their responses to these alterations are
detectable and measurable (Barbour et al. 1996).
There are a variety of benthic organisms that are frequently highly abundant in reservoirs; these organisms include Chironomidae, Oligochaeta, Bivalvia, Hirudinea,
and Chaoboridae (Takeda et al. 1990; Brooks et al. 2001;
Martins-Montanholi and Takeda 2001; Santos et al. 2006).
Chironomidae larvae exhibit a high diversity of ecological
features and are capable of surviving in many different environmental conditions, where some species are tolerant or
sensitive to low oxygen concentrations, extremes of temperature, pH, salinity, and trophy (Prat et al. 1992; Henry 1993;
Cranston 1995).
5.2 Basic Concepts
5.2.1 Lake Aging
Lake aging is a natural process that occurs on a geologic
timescale and results in the lake being filled with materials that are eroded and transported by tributaries, deposited
from the atmosphere and produced in the lake. Differences in
runoff and watershed characteristics cause lakes to fill-in at
different rates. The didactic natural succession is from lake
to pond, pond to marsh, marsh to meadow, and meadow to
dry land.
5.2.2 Brazilian Lacustrine Ecosystems
In Brazil, most lacustrine ecosystems are characterized as
lagoons owing to their geomorphological origin related to
the meanders of large rivers, coastal lagoons near the sea
in the “restinga” formation, or in the floodplains of Amazonia and the Pantanal. Some deep lakes can be found in the
Minas Gerais State in southeastern Brazil that originated in
the curves of the Doce River (Barbosa et al. 1999).
5.2.3 Anthropogenic (Cultural) Eutrophication
Human land use, deforestation, and untreated sewage disposal are common causes of eutrophication in freshwater.
Originally, eutrophication was known as the increased productivity of a lake as it ages. Often, an increased nutrient
supply from human activities results in an increase in the
biological production of the lake. Although the increased
production may increase the rate of lake filling, it is incorrect to define eutrophication as lake aging. A lake does not
die when it reaches a state of high productivity, but rather
when it has been completely filled in and no longer exists.
Lake filling results from production that occurs within the
lake, which may increase with eutrophication, and from the
deposition of organic and inorganic materials from outside
the lake, which is not related to lake eutrophication.
5.3 Too Much of a Good Thing
Natural eutrophication is a fairly slow and gradual process
that typically occurs over a period of many centuries as natural disturbances cause an imbalance between production and
consumption within the lake, and the lake slowly becomes
overfertilized. Although natural eutrophication is not rare
in nature, it does not occur frequently or quickly. However,
cultural eutrophication has become so common that the word
“eutrophication” has come to mean a very harmful increase
and acceleration of nutrient concentrations within a water
body. The situation is as if something receives too much fertilizer or has too much of a good thing.
5.3.1 What is Meant by Trophic State?
In temperate regions, the term “trophic” originally referred
to the nutrient status of an ecosystem. Esteves (1988) discussed the misuse of the lake typology approach in tropical regions and argued that it is necessary to consider the
naturally high nutrient concentrations in tropical lakes. His
paper, titled “Considerations on the application of typology
of temperate lakes to tropical lakes,” stressed the inadequacy
of its application. The metabolic patterns of tropical lakes are
completely different than temperate lacustrine ecosystems.
When the basic indicators used in the typology of temperate
lakes are applied to tropical lakes, the resulting classification
may cause the same ecosystem to be placed into different
categories.
Thienemann (1913) was the first author to use the distribution of benthic chironomid larva to classify lakes in Germany and, later, to propose his typology. In his studies of
volcanic lakes in the Eifel region, he discovered a different