Bacterial production and Microsystin in Lake Taihu

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Bacterial production and Microsystin in Lake
Taihu
GUANG GAO Nanjing Institute of Geography
Limnology, CAS
2007.03.26
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Outline

• Bacterial abundance, biomass and production in
  Lake Taihu
• Microsystin in Lake Taihu

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Main characteristics of this area Surface
area 120 Km2 Mean water depth
1.95 m Mean width 7.0
Km Mean length 15.0 Km
Meiliang Bay, Lake Taihu
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(No Transcript)
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• The river mouth, which was ca. 55 higher than
  the mean in Meiliang Bay and almost twice as high
  as the open lake.
• At river mouth, the total bacterial biomass was
  364225 µg C l-1, i.e. ca. 1.5 and 2.2 times
  higher than bay and the open lake.
• The difference between the highest and lowest
  value was ca. tenfold at the river mouth, only
  ca. fivefold were in Bay and the open lake.

Bacterial abundances and production
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• The mean percentage of active bacteria versus
  total bacterial abundance varied from 34 to 28
  in the river mouth, Meiliang Bay and the open
  lake.
• Variation of the active cells between sites was
  smaller than the variation in abundance and
  biomass.

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The relationship between total bacterial
abundance and the number of active bacteria
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The total phosphorus concentration vs the total
bacterial abundance (filled circles) or the
number of active bacteria (open circles) at
different sites of Lake Taihu.
The original total phosphorus data were taken
from the yearbook of TLLER, CAS.
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Correlation of bacterial carbon production
measured by both 3H-TdR (filled circles) and
14C-Leu (open circles) and phytoplankton
biomass. ( River mouth, r2 0.676, n13,
p0.001 and r2 0.680, n13, p0.001, Meiliang
Bay, r2 0.219, n39, p0.003 and r2 0.235,
n39, p0.002)
The original phytoplankton biomass data were
taken from the yearbook of TLLER, CAS.
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The Chl-a concentration vs the total bacterial
abundance (filled circles) or the number of
active bacteria (open circles).
The original phytoplankton biomass data were
taken from the yearbook of TLLER, CAS.
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Bacterial cell volumes were rather small !!
( All pictures were taken by using the same
sampling time and at the same magnification of
1250 X. Bar 10 µm. )
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No significant correlation between the water
temperature and bacterial cell volumes was found.

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• The cellular carbon content fluctuated ca.
  twofold during the year at all sites.
• No significant changes in the temporal
  distribution was found.

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Grazing Pressure
The biomass composition in different parts of the
lake
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The temp. and spatial distribution of Ciliate
abundance
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The relationship between ciliate abundance and
total bacterial abundance (filled circles) and
active bacterial abundance (open circles).
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Flagellate are the main bacteria consumer, which
can be contributed 90.7 of the grazing.
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Site 11, 12 the area covered by macrophyte Site
9 highly polluted area Site 0 river
mouth Site 3,5 the bay Site 7,8 the open lake
12 11 8 7 5 3 0
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Bacterial diversity by using PCR-DGGE method
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Microsystin in Lake Taihu
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Temporal distribution of Microsystin in
different part of Lake Taihu
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The whole lake distribution of Microsystin
Season distribution of Microsystin
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The spatial distribution of annual mean value of
Microsystins
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The relationship of parameters and the
concentration of Microsystin
Plt0.05 Plt0.01
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The relationship of biological parameters and the
concentration of Microsystin
Plt0.05 Plt0.01
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The change of MC concentration in the incubation
of natural algae bloom
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(A) Pure culture Microsystis 5105cells/ml
(B) Mixed culture, Microsystis sp.
2.5103cells/ml,Scendesmus obliqaus
2.5105cells/ml (C) Mixed culture, Microsystis
sp.2.5105cells/ml, scendesmus obliqaus
2.5103cells/ml
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Thank you for your attention!