140
36° 52′ N, is an HA lake situated on the NE
margin of the Qinghai–Xizang Plateau, about
135 km from the city of Xining. The lake has a
surface area, volume, maximum depth and average depth of 4,437 km
2 , 742 × 10
8 m
3 , 28.0 m
and 18.4 m, respectively. The lake sustains
>90,000 people living around its periphery,
most of whom earn their livelihood from crops
and cattle rearing. The climate is typical of high
plateau semi-arid grasslands, with average
monthly temperatures ranging between −12.7 °C
in January (minimum −30 °C) and 12.4 °C in
July (maximum 28 °C). The lake remains frozen
during November to March. Annual precipitation and evaporation are about 386 mm and
1,460 mm, respectively. It is a dimictic lake,
although moderately shallow and exposed to
strong northwesterly winds.
The basin has been endorheic since the
Quaternary, when tectonic changes sealed its outlet to the Yellow River (Academia Sinica 1979 ;
Chen 1982 , 1991 ) and isolated G . przewalskii
from its original stock (cf. G. eckloni ). Since
then, the lake has regressed to about one-third of
its original size and became saline. Studies
showed lake water generally has an average temperature of 1.8 °C, transparency 4.0 m, pH 9.4
(strongly alkaline), average DO 6.1 mg l
−1
, TA
2.2 mg l
−1
, TH 200 mg l
−1 , NO 3 0.039 mg l
−1 , PO 4
0.02 and salinity 12.5 g l
−1
. The water predominantly contains NaCl and MgSO 4 . The bottom
water generally remains oxygenated although H 2
S levels indicate some deoxygenation of the bottom sediments. The annual rainfall and evaporation are 380 and 1,450 mm year
−1
, respectively.
AM biomass 52 g m
−2 and phytoplankton and
zooplanktonic biomass (g m
−3 ) are 0.17 and 0.73,
respectively. c 80 % of the annual infl ow to the
lake is contributed by the rivers Buha, Shaliu and
Haergai. Irrigation weirs , constructed on the
Shaliu and Haergai during the late 1950s, have
reduced the spawning grounds for naked carp,
and only the Buha now provides unrestricted
access. However, the Buha has begun to downcut
its channel in response to the falling lake level.
This might be causing erosion and siltation which
may also affect spawning. The lake water level
has fallen >12 m in the past century (1.85 m in
1961–1990), mainly due to increasing aridity.
Also, the salinity increased from 12.5 g l
−1 in
1961 to 14.5 g l
−1 in 1989 (cf. Chen et al . 1990 ).
Wang’s review ( 1987 ) of about past 40 years
noted 78 species of phytoplankton in Qinghai
Province dominated by >20 genera of
Bacillariophyta and Chlorophyta. He also noted
60 zooplankton species, dominated by
Arctodiaptomus
denticornis
(Copepoda),
Hexarthra fennica (Rotifera) and Moina rectirostris (Cladocera), and 32 benthic species, primarily Chironomidae (Diptera).
Concomitant to above, 66 genera of phytoplankton have been recorded from the Qinghai
Lake. These mainly include 23 Bacillariophyta,
26 Chlorophyta and 12 Cyanophyta. Further,
dense growth of the chlorophyte, Cladophora ,
often prevents trawling activities in some areas.
On the other hand, the zooplankton comprises
57 taxa, which include 9 protozoans (mainly
Carchesium ), 21 rotifers ( Hexarthra fennica ),
17 cladocerans ( Moina rectirostris ) and 10
copepods ( Arctodiaptomus salinus ). Further, the
benthic fauna consists of 43 taxa, which include
an amphipod ( Gammarus sp.), 34 insects, 5
molluscs and 3 oligochaetes. However, the chironomids (especially Tendipes reductus complex) comprise c 87 % of the biomass. Notably,
AM species, like Potamogeton and Zannichellia
qinghaiensis occur sparsely in near-shore areas
(Chen 1987 ).
Notwithstanding the above, the Qinghai
Lake supports a fi shery of an endemic species
of naked carp, namely, Gymnocypris przewalskii (Cyprinidae: Schizothoracinae), which
was opened to commercial exploitation in
1958. Trawler catches peaked at 28,000 t in
1961 and declined until about 1970, when they
became more stable. In 1990, the total annual
catch was about 2,000 t. However, the species
is unusual amongst the cyprinids, in that it
migrates annually to spawn in rivers fl owing to
the lake. Its growth rate is slow as a consequence of the cold climate, and the fi sh generally take 7 years to attain sexual maturity and a
marketable size of 300 g.
The fi shery in Qinghai Lake is most important, as it supplied regional markets with about
6 Lakes of the World
36° 52′ N, is an HA lake situated on the NE
margin of the Qinghai–Xizang Plateau, about
135 km from the city of Xining. The lake has a
surface area, volume, maximum depth and average depth of 4,437 km
2 , 742 × 10
8 m
3 , 28.0 m
and 18.4 m, respectively. The lake sustains
>90,000 people living around its periphery,
most of whom earn their livelihood from crops
and cattle rearing. The climate is typical of high
plateau semi-arid grasslands, with average
monthly temperatures ranging between −12.7 °C
in January (minimum −30 °C) and 12.4 °C in
July (maximum 28 °C). The lake remains frozen
during November to March. Annual precipitation and evaporation are about 386 mm and
1,460 mm, respectively. It is a dimictic lake,
although moderately shallow and exposed to
strong northwesterly winds.
The basin has been endorheic since the
Quaternary, when tectonic changes sealed its outlet to the Yellow River (Academia Sinica 1979 ;
Chen 1982 , 1991 ) and isolated G . przewalskii
from its original stock (cf. G. eckloni ). Since
then, the lake has regressed to about one-third of
its original size and became saline. Studies
showed lake water generally has an average temperature of 1.8 °C, transparency 4.0 m, pH 9.4
(strongly alkaline), average DO 6.1 mg l
−1
, TA
2.2 mg l
−1
, TH 200 mg l
−1 , NO 3 0.039 mg l
−1 , PO 4
0.02 and salinity 12.5 g l
−1
. The water predominantly contains NaCl and MgSO 4 . The bottom
water generally remains oxygenated although H 2
S levels indicate some deoxygenation of the bottom sediments. The annual rainfall and evaporation are 380 and 1,450 mm year
−1
, respectively.
AM biomass 52 g m
−2 and phytoplankton and
zooplanktonic biomass (g m
−3 ) are 0.17 and 0.73,
respectively. c 80 % of the annual infl ow to the
lake is contributed by the rivers Buha, Shaliu and
Haergai. Irrigation weirs , constructed on the
Shaliu and Haergai during the late 1950s, have
reduced the spawning grounds for naked carp,
and only the Buha now provides unrestricted
access. However, the Buha has begun to downcut
its channel in response to the falling lake level.
This might be causing erosion and siltation which
may also affect spawning. The lake water level
has fallen >12 m in the past century (1.85 m in
1961–1990), mainly due to increasing aridity.
Also, the salinity increased from 12.5 g l
−1 in
1961 to 14.5 g l
−1 in 1989 (cf. Chen et al . 1990 ).
Wang’s review ( 1987 ) of about past 40 years
noted 78 species of phytoplankton in Qinghai
Province dominated by >20 genera of
Bacillariophyta and Chlorophyta. He also noted
60 zooplankton species, dominated by
Arctodiaptomus
denticornis
(Copepoda),
Hexarthra fennica (Rotifera) and Moina rectirostris (Cladocera), and 32 benthic species, primarily Chironomidae (Diptera).
Concomitant to above, 66 genera of phytoplankton have been recorded from the Qinghai
Lake. These mainly include 23 Bacillariophyta,
26 Chlorophyta and 12 Cyanophyta. Further,
dense growth of the chlorophyte, Cladophora ,
often prevents trawling activities in some areas.
On the other hand, the zooplankton comprises
57 taxa, which include 9 protozoans (mainly
Carchesium ), 21 rotifers ( Hexarthra fennica ),
17 cladocerans ( Moina rectirostris ) and 10
copepods ( Arctodiaptomus salinus ). Further, the
benthic fauna consists of 43 taxa, which include
an amphipod ( Gammarus sp.), 34 insects, 5
molluscs and 3 oligochaetes. However, the chironomids (especially Tendipes reductus complex) comprise c 87 % of the biomass. Notably,
AM species, like Potamogeton and Zannichellia
qinghaiensis occur sparsely in near-shore areas
(Chen 1987 ).
Notwithstanding the above, the Qinghai
Lake supports a fi shery of an endemic species
of naked carp, namely, Gymnocypris przewalskii (Cyprinidae: Schizothoracinae), which
was opened to commercial exploitation in
1958. Trawler catches peaked at 28,000 t in
1961 and declined until about 1970, when they
became more stable. In 1990, the total annual
catch was about 2,000 t. However, the species
is unusual amongst the cyprinids, in that it
migrates annually to spawn in rivers fl owing to
the lake. Its growth rate is slow as a consequence of the cold climate, and the fi sh generally take 7 years to attain sexual maturity and a
marketable size of 300 g.
The fi shery in Qinghai Lake is most important, as it supplied regional markets with about
6 Lakes of the World