58
M. Callisto et al.
aquatic vegetation and it has eliminated many populations
of native crayfish by spreading crayfish plague.
5.5 International Perspective
Cultural eutrophication, which is the excessive growth of
plants caused by anthropogenic nutrient enrichment, is recognized as the primary problem facing most surface waters
worldwide (Smith and Schindler 2009). The main driving
factors of cultural eutrophication are anthropogenic changes
to land use in the catchments and nutrient inputs from untreated sewages (Tundisi and Matsumura-Tundisi 2003). For
example, clearing forested catchments causes the long-term
loss of nutrients from the landscape, and these nutrients can
end up in the local water bodies. Applications of manure
or commercial fertilizer further increase terrestrial nutrient
exports. Fertilized soils can become nutrient saturated and
these nutrients can leak into receiving waters for decades
after the external nutrient additions are reduced or discontinued. The main potential effects of cultural eutrophication
caused by excessive inputs of phosphorus and nitrogen into
fresh and coastal waters are as follows:
• Increased biomass of phytoplankton and macrophyte vegetation.
• Increased biomass of consumer species.
• Shifts to bloom-forming algal species that might be toxic
or inedible.
• Increased biomass of benthic and epiphytic algae.
• Changes in species composition of macrophyte vegetation.
• Increased incidence of fish kills.
• Reductions in species diversity.
• Reductions in harvestable fish and shellfish biomass.
• Decreases in water transparency.
• Taste, odor, and drinking water treatment problems.
• Oxygen depletion.
• Decreases in the perceived esthetic value of the water
body.
5.6 Eutrophication and Infectious Disease
Risk
There is a direct link between eutrophication and disease risk.
Water-related diseases are a major cause of human morbidity
and mortality worldwide, and recent evidence suggests that
diseases can have a major impact among aquatic organisms.
Clearly, biological waste disposal activities, such as manure
applications to cropland, can simultaneously increase the
loading of phosphorus, nitrogen, and potentially hazardous
coliform bacteria to surface waters. However, enhanced nutrient loading may be sufficient on its own to influence the
abundance, composition, virulence, and survival of pathogens that are already present in aquatic ecosystems. Another
potential nutrient--pathogen interaction involves changes in
food quality. For example, if eutrophication influences the
nutrient content of food consumed by host organisms, then
changes in host nutrition could alter host–pathogen dynamics and ultimately result in infection. These potential links
between pathogens and nutrient availability could also be
important for managing human health in streams and rivers
with significant bathing-related activity. Recreational use
of waters can spread fecal-oral viruses (e.g., enteroviruses,
hepatitis A viruses, rotaviruses and others) that cause a broad
range of gastrointestinal, respiratory, eye, nose, ear, and skin
infections.
5.7 Eutrophication of Brazilian Freshwaters
5.7.1 A Case Study of Reservoirs
The Ibirité reservoir (19°07′00″–20°02′30″S, 44°07′30″–
44°05′00″W) was built in 1968 at an altitude of 773 m a.s.l.
This reservoir has an area of 2.8 km
2
, a water volume of
15,423,000 m
3
, and an average depth of 16 m. Most of the
hydrographic basin of the Ibirité Reservoir spans the municipalities of Ibirité (148,535 inhabitants) and Sarzedo
(23,282 inhabitants). The landscape of the reservoir basin is
dominated by Eucalyptus plantations, a large condominium
complex, small farms, and several industrial plants (PintoCoelho et al. 2010; Fig. 5.1).
The Vargem das Flores reservoir (19°53′30″–19°55′25″S,
44°07′22″–44°10′59″W) was built in 1971 and is situated at
838 m a.s.l. The reservoir has a water surface of 5.5 km
2
, a
water volume of 44,000,000 m
3
, and a maximum depth of
18 m. The maximum level sill spillway is 838.64 m with a
hydraulic retention time of 365 days. Approximately 12.3 ha
of the Vargem das Flores reservoir basin was designated as
an environmentally protected area (EPA) by law 16.197/06
(Minas Gerais, Brazil; Fig. 5.1).
The Serra Azul reservoir (19°54′09″–20°00′52″S,
44°23′16″–44°30′20″W), which has been operating for
approximately 30 years, is located at an altitude of 760 m
a.s.l., has a water surface of 8.9 km
2
, a water volume of
93,000,000 m
3
, and a maximum depth of 40 m. The maximum level sill spillway is 760 m with a hydraulic retention
time of 351 days. This reservoir, together with the Vargem
das Flores reservoir, provides the primary drinking water
supply to the metropolitan region of the State’s capital (ca.
4.8 million people). The protection area of the Basin is
27,200 ha, and the territory’s domain Companhia de Saneamento de Minas Gerais (COPASA) is 3,200 ha (COPASA
2000; Fig. 5.1).
M. Callisto et al.
aquatic vegetation and it has eliminated many populations
of native crayfish by spreading crayfish plague.
5.5 International Perspective
Cultural eutrophication, which is the excessive growth of
plants caused by anthropogenic nutrient enrichment, is recognized as the primary problem facing most surface waters
worldwide (Smith and Schindler 2009). The main driving
factors of cultural eutrophication are anthropogenic changes
to land use in the catchments and nutrient inputs from untreated sewages (Tundisi and Matsumura-Tundisi 2003). For
example, clearing forested catchments causes the long-term
loss of nutrients from the landscape, and these nutrients can
end up in the local water bodies. Applications of manure
or commercial fertilizer further increase terrestrial nutrient
exports. Fertilized soils can become nutrient saturated and
these nutrients can leak into receiving waters for decades
after the external nutrient additions are reduced or discontinued. The main potential effects of cultural eutrophication
caused by excessive inputs of phosphorus and nitrogen into
fresh and coastal waters are as follows:
• Increased biomass of phytoplankton and macrophyte vegetation.
• Increased biomass of consumer species.
• Shifts to bloom-forming algal species that might be toxic
or inedible.
• Increased biomass of benthic and epiphytic algae.
• Changes in species composition of macrophyte vegetation.
• Increased incidence of fish kills.
• Reductions in species diversity.
• Reductions in harvestable fish and shellfish biomass.
• Decreases in water transparency.
• Taste, odor, and drinking water treatment problems.
• Oxygen depletion.
• Decreases in the perceived esthetic value of the water
body.
5.6 Eutrophication and Infectious Disease
Risk
There is a direct link between eutrophication and disease risk.
Water-related diseases are a major cause of human morbidity
and mortality worldwide, and recent evidence suggests that
diseases can have a major impact among aquatic organisms.
Clearly, biological waste disposal activities, such as manure
applications to cropland, can simultaneously increase the
loading of phosphorus, nitrogen, and potentially hazardous
coliform bacteria to surface waters. However, enhanced nutrient loading may be sufficient on its own to influence the
abundance, composition, virulence, and survival of pathogens that are already present in aquatic ecosystems. Another
potential nutrient--pathogen interaction involves changes in
food quality. For example, if eutrophication influences the
nutrient content of food consumed by host organisms, then
changes in host nutrition could alter host–pathogen dynamics and ultimately result in infection. These potential links
between pathogens and nutrient availability could also be
important for managing human health in streams and rivers
with significant bathing-related activity. Recreational use
of waters can spread fecal-oral viruses (e.g., enteroviruses,
hepatitis A viruses, rotaviruses and others) that cause a broad
range of gastrointestinal, respiratory, eye, nose, ear, and skin
infections.
5.7 Eutrophication of Brazilian Freshwaters
5.7.1 A Case Study of Reservoirs
The Ibirité reservoir (19°07′00″–20°02′30″S, 44°07′30″–
44°05′00″W) was built in 1968 at an altitude of 773 m a.s.l.
This reservoir has an area of 2.8 km
2
, a water volume of
15,423,000 m
3
, and an average depth of 16 m. Most of the
hydrographic basin of the Ibirité Reservoir spans the municipalities of Ibirité (148,535 inhabitants) and Sarzedo
(23,282 inhabitants). The landscape of the reservoir basin is
dominated by Eucalyptus plantations, a large condominium
complex, small farms, and several industrial plants (PintoCoelho et al. 2010; Fig. 5.1).
The Vargem das Flores reservoir (19°53′30″–19°55′25″S,
44°07′22″–44°10′59″W) was built in 1971 and is situated at
838 m a.s.l. The reservoir has a water surface of 5.5 km
2
, a
water volume of 44,000,000 m
3
, and a maximum depth of
18 m. The maximum level sill spillway is 838.64 m with a
hydraulic retention time of 365 days. Approximately 12.3 ha
of the Vargem das Flores reservoir basin was designated as
an environmentally protected area (EPA) by law 16.197/06
(Minas Gerais, Brazil; Fig. 5.1).
The Serra Azul reservoir (19°54′09″–20°00′52″S,
44°23′16″–44°30′20″W), which has been operating for
approximately 30 years, is located at an altitude of 760 m
a.s.l., has a water surface of 8.9 km
2
, a water volume of
93,000,000 m
3
, and a maximum depth of 40 m. The maximum level sill spillway is 760 m with a hydraulic retention
time of 351 days. This reservoir, together with the Vargem
das Flores reservoir, provides the primary drinking water
supply to the metropolitan region of the State’s capital (ca.
4.8 million people). The protection area of the Basin is
27,200 ha, and the territory’s domain Companhia de Saneamento de Minas Gerais (COPASA) is 3,200 ha (COPASA
2000; Fig. 5.1).