94
W. Y. B. Chang
population density has sharply increased the need for lake
resources and has multiplied the uses of lake environments
(Chang 1990). These great lakes in this area not only serve
as sources for drinking water, fish, and aquatic food production, but also play important roles in transportation, flood
control, and waste disposal. In general, large lakes close to
urban centers also receive disproportionately large amounts
of household and industrial wastes. As a result, they have
become increasingly eutrophic and have elevated concentrations of organic toxics, with frequent occurrence of cyanobacteria blooms.
The economic initiatives of the 1980s stimulated major
industrial development resulting in a great increase in industrial effluents. Since industries were treating only about
25 % of these effluents (even that amount is an optimistic estimate), most of the raw effluents, containing a large
number of contaminants, have been draining into lakes.
High levels of metals and toxic organics have already been
found in lake sediments and benthic fishes in large lakes
close to urban centers, such as Lakes Tai and Chao. These
contaminants include mercury, arsenic, phenol, copper,
cyanide, zinc, lead, and chromium, and can be readily associated with the nearby major industrial sources (Nanjing
Institute of Geography 1982; Sun and Wu 1989; Sun and
Huang 1993).
The economic initiatives that began in the 1980s also
led to new sources of pollution from rural industry. Prior
to the early 1980s, most major Chinese industries were
situated in urban areas. The primary sources of industrial
pollution were the industries in urban centers and this situation was known to local inhabitants. However, in the late
1980s, many rural industries sprouted up. These industries
are usually operated by one or a few families and are spread
throughout all rural communities in China. They are generally poorly equipped with little or no environmental treatment facilities. These rural industries have become a major
source of toxic chemicals and have been responsible for the
spread of these chemicals from primarily urban centers to
many rural communities, which are experiencing increasing amounts and deadlier types of pollution. These rural industry sources have had an extensive impact on tributaries
and lakes in many places quite far from previously known
pollution sources.
Extensive use of the littoral areas of lakes for aquaculture
and farming to increase the food production in China has
led to an increase in eutrophication and is responsible for
the substantial reduction in lake areas in the PDB. The rate
of reduction in the size of the PDB great lakes is high. For
example, increased use of wetland and littoral zones in Lake
Tai beginning in the 1950s significantly reduced the lake
size. The total area of the littoral zone converted to farmland
and ponds between 1950 and 1980 was 160 km
2
(Sun and
Huang 1993). The highest annual rate of conversion was during the 1970s.
The conversion of lake areas for rice and fish farming also had major ecological effects on Lake Tai (Chang
1996). This conversion reduced the area covered by aquatic vegetation, which is important to many littoral species
for spawning, foraging, and protection during maturation.
As a result, many species that depend on this environment
have been declining, most notably fish species such as
common carp Cyprinus carpio and crucian carp Carassius
auratus. With the reduction in carp species, the families
Engraulidae and Salangidae, which prefer open water and
prey primarily on large zooplankton, have quickly become
dominant in the lake. These opportunistic fish species are
small in size (adults have an average size of 7–10 cm), with
a short maturation period of about 1 year. Wong showed
an inverse relationship between the population of fish
species Engraulidae and Salangidae and the zooplankton
population in the lake. A large increase in Engraulidae
and Salangidae populations has had a major effect on the
zooplankton population. The depressed zooplankton population, in turn, results in a relatively high density in the
phytoplantkon population. The effects of littoral conversion have significantly changed the trophic dynamics and
the fish population in Lake Tai. This could indirectly affect the effort to control unwanted algal blooms in that lake
(Chang 1996).
The Chinese government has recognized the severe impacts of littoral conversions, which include the reduction of
the floodwater holding capacity of the large lakes and significant changes in lake ecosystems. In 1980s, it announced
a program of returning the farmland previously claimed from
lakes to lake use. This program was only minimally successful since the trend of population growth and need to use this
area for housing construction and urban expansion acted
against it.
8.4 Lake Management
8.4.1 Institutional Arrangements
Management of Chinese lakes falls under several different
authorities. The Ministry of Water Resources is responsible
for flood controls and the construction of dams and weirs.
The National Environmental Protection Administration
(NEPA) has the authority for pollution regulation and for
establishment of environmental laws related to lakes. The
Ministry of Agriculture provides guidelines for managing
fisheries and natural resources, which are primarily focused
on increasing the production of fish and aquatic products.
The daily management of lakes is, however, the responsibility of provincial, county, and township authorities. The level
W. Y. B. Chang
population density has sharply increased the need for lake
resources and has multiplied the uses of lake environments
(Chang 1990). These great lakes in this area not only serve
as sources for drinking water, fish, and aquatic food production, but also play important roles in transportation, flood
control, and waste disposal. In general, large lakes close to
urban centers also receive disproportionately large amounts
of household and industrial wastes. As a result, they have
become increasingly eutrophic and have elevated concentrations of organic toxics, with frequent occurrence of cyanobacteria blooms.
The economic initiatives of the 1980s stimulated major
industrial development resulting in a great increase in industrial effluents. Since industries were treating only about
25 % of these effluents (even that amount is an optimistic estimate), most of the raw effluents, containing a large
number of contaminants, have been draining into lakes.
High levels of metals and toxic organics have already been
found in lake sediments and benthic fishes in large lakes
close to urban centers, such as Lakes Tai and Chao. These
contaminants include mercury, arsenic, phenol, copper,
cyanide, zinc, lead, and chromium, and can be readily associated with the nearby major industrial sources (Nanjing
Institute of Geography 1982; Sun and Wu 1989; Sun and
Huang 1993).
The economic initiatives that began in the 1980s also
led to new sources of pollution from rural industry. Prior
to the early 1980s, most major Chinese industries were
situated in urban areas. The primary sources of industrial
pollution were the industries in urban centers and this situation was known to local inhabitants. However, in the late
1980s, many rural industries sprouted up. These industries
are usually operated by one or a few families and are spread
throughout all rural communities in China. They are generally poorly equipped with little or no environmental treatment facilities. These rural industries have become a major
source of toxic chemicals and have been responsible for the
spread of these chemicals from primarily urban centers to
many rural communities, which are experiencing increasing amounts and deadlier types of pollution. These rural industry sources have had an extensive impact on tributaries
and lakes in many places quite far from previously known
pollution sources.
Extensive use of the littoral areas of lakes for aquaculture
and farming to increase the food production in China has
led to an increase in eutrophication and is responsible for
the substantial reduction in lake areas in the PDB. The rate
of reduction in the size of the PDB great lakes is high. For
example, increased use of wetland and littoral zones in Lake
Tai beginning in the 1950s significantly reduced the lake
size. The total area of the littoral zone converted to farmland
and ponds between 1950 and 1980 was 160 km
2
(Sun and
Huang 1993). The highest annual rate of conversion was during the 1970s.
The conversion of lake areas for rice and fish farming also had major ecological effects on Lake Tai (Chang
1996). This conversion reduced the area covered by aquatic vegetation, which is important to many littoral species
for spawning, foraging, and protection during maturation.
As a result, many species that depend on this environment
have been declining, most notably fish species such as
common carp Cyprinus carpio and crucian carp Carassius
auratus. With the reduction in carp species, the families
Engraulidae and Salangidae, which prefer open water and
prey primarily on large zooplankton, have quickly become
dominant in the lake. These opportunistic fish species are
small in size (adults have an average size of 7–10 cm), with
a short maturation period of about 1 year. Wong showed
an inverse relationship between the population of fish
species Engraulidae and Salangidae and the zooplankton
population in the lake. A large increase in Engraulidae
and Salangidae populations has had a major effect on the
zooplankton population. The depressed zooplankton population, in turn, results in a relatively high density in the
phytoplantkon population. The effects of littoral conversion have significantly changed the trophic dynamics and
the fish population in Lake Tai. This could indirectly affect the effort to control unwanted algal blooms in that lake
(Chang 1996).
The Chinese government has recognized the severe impacts of littoral conversions, which include the reduction of
the floodwater holding capacity of the large lakes and significant changes in lake ecosystems. In 1980s, it announced
a program of returning the farmland previously claimed from
lakes to lake use. This program was only minimally successful since the trend of population growth and need to use this
area for housing construction and urban expansion acted
against it.
8.4 Lake Management
8.4.1 Institutional Arrangements
Management of Chinese lakes falls under several different
authorities. The Ministry of Water Resources is responsible
for flood controls and the construction of dams and weirs.
The National Environmental Protection Administration
(NEPA) has the authority for pollution regulation and for
establishment of environmental laws related to lakes. The
Ministry of Agriculture provides guidelines for managing
fisheries and natural resources, which are primarily focused
on increasing the production of fish and aquatic products.
The daily management of lakes is, however, the responsibility of provincial, county, and township authorities. The level