145
total area of Mongolia and c 15.9 % of the country’s
aquatic resources. There are >900 lakes in this
area. 72 % of these lakes are located in catchments of the rivers Onon, Ulz and Halhin Gol.
Further, >85 % of the lakes in this region are
<100 ha. The largest lake is the fl ow-through
freshwater Lake Buyr (615 km
2
), which has the
highest fi sh production of all Mongolian lakes.
The saline Lake Huh, which has no outfl ow, is of
medium size (52.4 km
2
) and is located at the lowest altitude in Mongolia (560 m).
Copepoda, Cladocera and BGA dominate the
plankton. The major AM are reed and pondweed.
Crayfi sh is common in catchments of the rivers
Onon and Balzh. Lakes Buyr and Halhin have the
crustacean Leander modestus . The common molluscs are Margarita daurica , Anodonta arcaformis and Cristata plicata .
Central Asian Internal Basin of Mongolia is
the largest of the three regions. It covers c 65 %
of Mongolia and contains c 32 % of its water
resources. It includes the mountain lakes of the
Mongolian Altai, waterbodies of the Gobi Valley
and some lakes of the Hangayn Mountain plateau. The largest Mongolian lakes are situated in
the Gobi Valley, in spite of a very low annual
rainfall of only about 100 mm and a high evaporation rate of 900–1,000 mm. There are three lake
complexes within the Great Lakes Valley, namely,
the Altai mountain lakes, the Hangayn Plateau
lakes and the Great Lakes.
Altai mountain lakes are situated in valleys of
mountain ranges of the Mongolian Altai, Tannu
Ola and Hangayn. Of the large lakes, namely,
Hoton, Horgon, Dayan, Uureg, Achit, Tolbo, Uvs
and Hongor-Ulen, all but two are of a fl owthrough freshwater type. Saline lakes Uvs (20 m
deep) and Uureg (27 m deep) are rich in fi sh.
The Hangayn Plateau lakes are located in
the northwest of the Hangayn Plateau, 1,700–
2,000 m MSL. Some of the large lakes are
Hangayn-Har, Ulaagchnyi-Har, Heh, Oigon,
Telmen and Sangiin Dalai . The fi rst four have
freshwater and a maximum depth of 50 m.
Rotifers and copepods dominate the zooplankton, with an average annual biomass of
2.8 g m
−3 . Lake Ulaagchnyi-Har is rich in
plankton, but it had no indigenous fi sh. Three
fi sh species were, therefore, introduced,
namely, northern whitefi sh, Arctic cisco and
Siberian cisco. They have established stocks
suffi cient to support a fi shery. The other lakes
are saline and have no outfl ow. Each of these
has its specifi c plankton, according to the salt
concentration.
The complex of Great Lakes includes lakes
Khyargas , Ayrag, Har, Har Us and Durgun. The
fl ow-through freshwater lakes Har and Har Us
have an average depth of 2–6 m. Khyargas,
Durgun and Uureg and some other lakes are
saline and have no outfl ow. Their maximum
depth is 80 m. All these lakes have a very similar hydrobiology. Both the freshwater (FW) and
saline lakes contain fi sh. Rotifers and copepods
dominate zooplankton, the biomass of which
ranges from 0.31 to 0.98 g m
−3 in summer and
from 0.13 to 0.32 g m
−3 in winter. BGA dominate the phytoplankton. Pondweed, yellow
water lily and hornwort are the dominant AM.
The fi sh fauna consists of a small number of
species, dominated by the indigenous polymorphic genera Oreoleuciscus and Thymallus . The
lakes are rich in waterfowl, muskrat and the
Asian beaver.
The lake region of the Gobi basin has more
than 20 lakes. They are not large and most of
them dry up periodically. The largest of these
temporary lakes are the saline lakes Boon
Tsagaan, Orog Nuur and Ulaan, situated
between the Hangayn Plateau and Gobi Altai.
All waterbodies are shallow (3–5 m deep).
Rotifers dominate zooplankton which peaks in
July–August. The mean biomass of zooplankton ranges from 1.3 to 2.1 g m
−3 . Benthic invertebrates are dominated by Phasganophora
brevipennis , Diura nanseni , Aeshna affi nis ,
Sympetrum fl aveolum , Limnophilus abstrusus
and Oecetis ochracea . The lakes are either oligotrophic or mesotrophic. The shallow water
of these lakes is relatively warm and rich in
AM. Hence, it has been proposed to introduce
grass carp in them.
For more information on hydrobiology of
Mongolian lakes, see Dulma ( 1979 ). Williams
( 1991 ) has reviewed the limnology of Mongolian
saline lakes.
6.9 High Altitude (HA) Lentic Bodies
total area of Mongolia and c 15.9 % of the country’s
aquatic resources. There are >900 lakes in this
area. 72 % of these lakes are located in catchments of the rivers Onon, Ulz and Halhin Gol.
Further, >85 % of the lakes in this region are
<100 ha. The largest lake is the fl ow-through
freshwater Lake Buyr (615 km
2
), which has the
highest fi sh production of all Mongolian lakes.
The saline Lake Huh, which has no outfl ow, is of
medium size (52.4 km
2
) and is located at the lowest altitude in Mongolia (560 m).
Copepoda, Cladocera and BGA dominate the
plankton. The major AM are reed and pondweed.
Crayfi sh is common in catchments of the rivers
Onon and Balzh. Lakes Buyr and Halhin have the
crustacean Leander modestus . The common molluscs are Margarita daurica , Anodonta arcaformis and Cristata plicata .
Central Asian Internal Basin of Mongolia is
the largest of the three regions. It covers c 65 %
of Mongolia and contains c 32 % of its water
resources. It includes the mountain lakes of the
Mongolian Altai, waterbodies of the Gobi Valley
and some lakes of the Hangayn Mountain plateau. The largest Mongolian lakes are situated in
the Gobi Valley, in spite of a very low annual
rainfall of only about 100 mm and a high evaporation rate of 900–1,000 mm. There are three lake
complexes within the Great Lakes Valley, namely,
the Altai mountain lakes, the Hangayn Plateau
lakes and the Great Lakes.
Altai mountain lakes are situated in valleys of
mountain ranges of the Mongolian Altai, Tannu
Ola and Hangayn. Of the large lakes, namely,
Hoton, Horgon, Dayan, Uureg, Achit, Tolbo, Uvs
and Hongor-Ulen, all but two are of a fl owthrough freshwater type. Saline lakes Uvs (20 m
deep) and Uureg (27 m deep) are rich in fi sh.
The Hangayn Plateau lakes are located in
the northwest of the Hangayn Plateau, 1,700–
2,000 m MSL. Some of the large lakes are
Hangayn-Har, Ulaagchnyi-Har, Heh, Oigon,
Telmen and Sangiin Dalai . The fi rst four have
freshwater and a maximum depth of 50 m.
Rotifers and copepods dominate the zooplankton, with an average annual biomass of
2.8 g m
−3 . Lake Ulaagchnyi-Har is rich in
plankton, but it had no indigenous fi sh. Three
fi sh species were, therefore, introduced,
namely, northern whitefi sh, Arctic cisco and
Siberian cisco. They have established stocks
suffi cient to support a fi shery. The other lakes
are saline and have no outfl ow. Each of these
has its specifi c plankton, according to the salt
concentration.
The complex of Great Lakes includes lakes
Khyargas , Ayrag, Har, Har Us and Durgun. The
fl ow-through freshwater lakes Har and Har Us
have an average depth of 2–6 m. Khyargas,
Durgun and Uureg and some other lakes are
saline and have no outfl ow. Their maximum
depth is 80 m. All these lakes have a very similar hydrobiology. Both the freshwater (FW) and
saline lakes contain fi sh. Rotifers and copepods
dominate zooplankton, the biomass of which
ranges from 0.31 to 0.98 g m
−3 in summer and
from 0.13 to 0.32 g m
−3 in winter. BGA dominate the phytoplankton. Pondweed, yellow
water lily and hornwort are the dominant AM.
The fi sh fauna consists of a small number of
species, dominated by the indigenous polymorphic genera Oreoleuciscus and Thymallus . The
lakes are rich in waterfowl, muskrat and the
Asian beaver.
The lake region of the Gobi basin has more
than 20 lakes. They are not large and most of
them dry up periodically. The largest of these
temporary lakes are the saline lakes Boon
Tsagaan, Orog Nuur and Ulaan, situated
between the Hangayn Plateau and Gobi Altai.
All waterbodies are shallow (3–5 m deep).
Rotifers dominate zooplankton which peaks in
July–August. The mean biomass of zooplankton ranges from 1.3 to 2.1 g m
−3 . Benthic invertebrates are dominated by Phasganophora
brevipennis , Diura nanseni , Aeshna affi nis ,
Sympetrum fl aveolum , Limnophilus abstrusus
and Oecetis ochracea . The lakes are either oligotrophic or mesotrophic. The shallow water
of these lakes is relatively warm and rich in
AM. Hence, it has been proposed to introduce
grass carp in them.
For more information on hydrobiology of
Mongolian lakes, see Dulma ( 1979 ). Williams
( 1991 ) has reviewed the limnology of Mongolian
saline lakes.
6.9 High Altitude (HA) Lentic Bodies