Bacterial production and Microsystin in Lake Taihu GUANG GAO Nanjing Institute of Geography &...

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Bacterial production and MicrBacterial production and Microsystin in Lakeosystin in Lake TaihuTaihu

GUANG GAO

Nanjing Institute of Geography & Limnology, CAS

2007.03.26

OutlineOutline

Bacterial abundance, biomass aBacterial abundance, biomass and production in Lake Taihund production in Lake Taihu

Microsystin in Lake TaihuMicrosystin in Lake Taihu

Meiliang Bay, Lake Taihu

Main characteristics of this area:

Surface area: 120 Km2

Mean water depth: 1.95 mMean width: 7.0 KmMean length: 15.0 Km

May/98 Jun Jul Aug Sep Oct Nov Dec Jan/99 Feb Mar Apr May/99

BA BBBCP

•The river mouth, which was ca.

55% higher than the mean in M

eiliang Bay and almost twice as

high as the open lake.

• At river mouth, the total bacte

rial biomass was 364±225 μg C

l-1, i.e. ca. 1.5 and 2.2 times high

er than bay and the open lake.

• The difference between the hi

ghest and lowest value was ca.

tenfold at the river mouth, only

ca. fivefold were in Bay and the

open lake.

Bacterial abundances and production

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.

cell production Active cells

0 5 10 15 20 25 30 35 40

ells m

0 5 10 15 20 25 30 35 40

ells m

Bacterial abundance (*106 cells ml-1

0 5 10 15 20 25 30 35 40

ells m

The relationship between total bacterial abundance and the number of active bacteria

Total phosphorus concentration (mg l-1)

00.0 0.1 0.2 0.3 0.4 0.5 0.6

6 cell

00.0 0.1 0.2 0.3 0.4 0.5 0.6

6 cell

00.0 0.1 0.2 0.3 0.4 0.5 0.6

6 cell

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.

0 5 10 15 20

0 20 40 60 80 100 120 140 160 180

Phytoplankton biomass (mg l-1)

0 1 2 3 4 5

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, n=13, p=0.001 and r2 =0.680, n=13, p=0.001, Meiliang Bay, r2 =0.219, n=39, p=0.003 and r2 =0.235, n=39, p=0.002)

The original phytoplankton biomass data were taken from

the yearbook of TLLER, CAS.

0 20 40 60 80 100 120 140 160 180

rial ab

ells m

0 20 40 60 80 100 120 140 160 180

rial ab

ells m

Chl-a concentration (g l-1

0 20 40 60 80 100 120 140 160 180

rial ab

ells m

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.

Cell Size (m3)

.001 .01 .1 1

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. )

X Data

0 5 10 15 20 25 30 35

Water Temperature (oC)

0 5 10 15 20 25 30 35

No significant correlation between the water temperature and bacterial cell volumes was found.

May98Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May99

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

AreaArea ProtozoaProtozoa RotiferRotifer CladoceraCladocera CopepodaCopepoda

River River Mouth Mouth

Mean±S.EMean±S.E7.9±2.07.9±2.0

( n =60)( n =60)

43.9±4.543.9±4.5

( n =60)( n =60)

39.0±4.539.0±4.5

( n = 60 )( n = 60 )

9.3±2.49.3±2.4

( n = 67 )( n = 67 )

Meiliang Meiliang Bay Bay

Mean±S.E Mean±S.E 1.2±0.21.2±0.2

( n = 180)( n = 180)

12.3±1.712.3±1.7

( n = 180)( n = 180)

67.8±2.567.8±2.5

( n = 180)( n = 180)

18.2±1.818.2±1.8

( n = 180 )( n = 180 )

Open Open area area

MeanMean±±S.ES.E1.4±0.51.4±0.5

( n = 60 )( n = 60 )

4.34.3±1.4±1.4

( n =60 )( n =60 )

58.158.1±±4.54.5

( n = 60 )( n = 60 )

36.236.2±±4.44.4

( n = 60)( n = 60)

The biomass composition in different parts of the lake

Grazing Pressure

May98 Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May99

The temp. and spatial distribution of Ciliate abundance

Bacterial abundance (*109 cells l-1)

0 5 10 15 20 25 30 35 40

*103 c

The relationship between ciliate abundance and total bacterial abundance (filled circles) and active bacterial abundance (open circles).

32μm 16μm 1μm0

flagellate grazing rate (d-1)

Bacterial growth rate (d-1)Grazing (mgC.m-3.d-1)

Flagellate are the main bacteria consumer, which can be contributed 90.7% of the grazing.

12 11 8 7 5 3 0 9

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

Bacterial diversity by using PCR-DGGE method

Microsystin in Lake TaihuMicrosystin in Lake Taihu

Temporal distribution of Microsystin in different part of Lake Taihu

The whole lake distribution of Microsystin Season distribution of Microsystin

The spatial distribution of annual mean value of Microsystins

The relationship of parameters and the concentration of Microsystin

River mouth Meiliang Bay Open Lake Wuli Bay

Water Temperature

0.593* 0.818** 0.119 -0.002

Transparency 0.401 -0667* 0.368 0.060

DO 0.448 -0.315 -0.067 -0.310

SS -0.566 0.673 -0.357 0.196

TN -0.853** -0.627* -0.277 -0.389

TP 0.692* 0.874** -0.371 0.077

PO43- 0.172 0.000 0.031 0.559

Chla 0.168 0.594* 0.396 -0.644*

PH 0.310 0.755** 0.302 -0.533

CODMN 0.601* 0.846** 0.070 -0.413

*P<0.05; **P<0.01

The relationship of biological parameters and the concentration of Microsystin

River mouth Meiliang Bay Open Lake Wuli Bay

Algal biomass 0.021 0.818** 0.487 -0.525

Cyanobacteriabiomass

0.593* 0.720** 0.119 -0.002

Rotiferbiomass

0.748** 0.505 0.522 0.214

Protozoa biomass

0.333 0.424 0.238 0.294

Cladocera, Copepodabiomass

-0.42 -0.308 0.252 -0.165

*P<0.05; **P<0.01

1000.0

1200.0

1400.0

1 3 5 7 9 11

Incubation time (d)

The change of MC concentration in the incubation of natural algae bloom

(A) Pure culture Microsystis: 5×105cells/ml (B) Mixed culture, Microsystis sp. :2.5×103cells/ml ， Scendesmus obliqaus: 2.5×105cells/ml (C) Mixed culture, Microsystis sp.:2.5×105cells/ml ， scendesmus obliqaus 2.5×103cells/ml

Thank you Thank you

for your for your attention!attention!

Bacterial production and Microsystin in Lake Taihu GUANG GAO Nanjing Institute of Geography &...

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