evolution of lake erhai ecologiecal system in china...evolution of lake erhai ecologiecal system in...

Evolution of Lake Erhai ecological system in China

Prof. Wang Sheng-Rui

Research Center for Lake Ecology & Environments of CRAES5 August 2013

Outline

1 Overview of Lake Erhai ecological environment

鄱阳湖主要生态环境问题鄱阳湖主要生态环境问题鄱阳湖主要生态环境问题鄱阳湖主要生态环境问题2 Analysis the reason of the aquatic plant degradatio n

3 Focused question

1.1 General situation of Lake Erhai (south-west in China)

Picture of Erhai Lake

Basin areas 2565km2，area 251km2

Mean deep 10.51 m， Rivers 26 (inter rivers 25, and out rivers 1) Capacity of water 2700 M m3

，interring water 800 M m3, water sources is short

Location of Lake Erhai

Chorography of Lake Erhai

1. Overview of Lake Erhai ecological environment problems

1992-2010年洱海水体TN浓度变化

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

1992

1993

1994

1995

1

996

1997

1998

1999

200

0

2001

2

002

2003

2004

2005

200

6

2007

2

008

2009

2010

年份

浓度

(mg/L)

Class ⅢⅢⅢⅢ

ClassⅡⅡⅡⅡ

1.2 The eutrophic level of Lake Erhai is not optimistic ( N, P increase)

water quality decrease from class ⅡⅡⅡⅡto class ⅢⅢⅢⅢ

5 Year

1. Overview of Lake Erhai ecological environment

Year

Concentration of N Lake Erhai from 1992-2010

1.3 N, P pollution in the sediment is heavier.

Although the amount of its released is small, flux of N and P

released accounting for about 10-15 and 15-20% of the total.

But its release risks can not be ignored (N/P heavy).

北北北北

部部部部

中中中中

部部部部

南南南南

部部部部

污染层和过渡层厚度放大了100倍（10-30厘米）

Polluted level

transition layer Normal

sediment layer


钙结合态磷钙结合态磷钙结合态磷钙结合态磷

0

50

100

150

200

250

300

350

巢

湖

巢

湖

巢

湖

巢

湖

洞

庭

湖

洞

庭

湖

洞

庭

湖

洞

庭

湖

洪

泽

湖

洪

泽

湖

洪

泽

湖

洪

泽

湖

太

湖

太

湖

太

湖

太

湖

东

湖

东

湖

东

湖

东

湖

洱

海

洱

海

洱

海

洱

海

HC

l-P(m

g/kg

)

残渣磷残渣磷残渣磷残渣磷

0

50

100

150

200

巢

湖

巢

湖

巢

湖

巢

湖

洞

庭

湖

洞

庭

湖

洞

庭

湖

洞

庭

湖

洪

泽

湖

洪

泽

湖

洪

泽

湖

洪

泽

湖

太

湖

太

湖

太

湖

太

湖

东

湖

东

湖

东

湖

东

湖

洱

海

洱

海

洱

海

洱

海

NaO

H-P

(mg/

kg)

0

5

10

15

20

25

30

巢湖洞庭湖洪泽湖太湖东湖洱海

含量

(mg/

g)

结晶态铁

有机络合态铁

无定形铁

0

2

4

6

8

10

12

14

16

18

巢湖洞庭湖洪泽湖太湖东湖洱海

含量

(mg/

g)

结晶态铝

有机络合态铝

无定形铝

Ca-P （（（（Calcium binding phosphorus and R-P (residual phosphorus ) content is high (50%-60%), is one of the causes of water quality in

Erhai good

Distribution of iron, aluminum, manganese and phosphorus is same, and P mainly

related with the amorphous iron and aluminum content

1850

1870

1890

1910

1930

1950

1970

1990

2010

0 2 4 6TN(g/kg)

1850

1870

1890

1910

1930

1950

1970

1990

2010

0 400 800

TP(mg/kg)

1850

1870

1890

1910

1930

1950

1970

1990

2010

-27 -24

δ13

C/‰

1850

1870

1890

1910

1930

1950

1970

1990

2010

4 5 6 7δ

15N/‰ � Nutrition levels increased faster, aquatic vegetation increase, organic matter and N, P of sediment from main source of submerged macrophytes 1970s� Submerged vegetation degeneration, algal biomass increased significantly, organic matter and N, P of sediment derived from algae increased 1990s

1.3 Pollution characteristics and sediment conditions determine the

flux is small (release of N and P in the sediments of Erhai)

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

70年代 1983 1988 1994 1998 2003 2004 2009

覆盖率（%）


1.4 Severe degradation of aquatic plants

The single dominant community appear ( in those years )

The coverage was about 20-40% in the 1970s to 1990s

2003 due to the deterioration of water quality, the coverage is

only 10%, to about 5% in 2009 (up to now)

The aquatic plants coverage of Lake Erhai from 1970s to 2009

0

500

1000

1500

2000

2500

3000

3500

1992 1994 1996 1998 2000 2002 2004 2006 2008 2010

x104 c

ells

/L

微束鱼腥藻

1.5 The dominant phytoplankton Cyanophyta, density increased

in recent years to keep 107 / high value rise

Part of the lake（（（（Lake Bay））））sometime occur water bloom

Year


0

500

1000

1500

2000

2500

3000

3500

1992 1994 1996 1998 2000 2002 2004 2006 2008 2010

x104 c

ells

/L

微束鱼腥藻

1.5 The dominant phytoplankton Cyanophyta, density increased

in recent years to keep 107 / high value rise

Part of the lake（（（（Lake Bay））））sometime occur water bloom

Year


2009年年年年2003年年年年

北部北部北部北部

中部中部中部中部

南部南部南部南部

1.6 Benthic animal also presents the characteristics of eutrophication,

the dominant species by clean succession for eutrophication

common species, aquatic insects and Oligochaeta increased

0

100

200

300

400

500

600

19

21

46

68

73

84

93

100

105

117

121

132

142

177

182

209

221

密度(ind./m2)

水生昆虫

软体动物

寡毛类

北部北部北部北部中部中部中部中部南部南部南部南部

1128112811281128

寡毛类寡毛类寡毛类寡毛类软体动物软体动物软体动物软体动物

Clean species changed into the polluted species

河蚬河蚬河蚬河蚬、、、、螺蛳螺蛳螺蛳螺蛳

苏氏尾鳃蚓苏氏尾鳃蚓苏氏尾鳃蚓苏氏尾鳃蚓

水丝蚓水丝蚓水丝蚓水丝蚓、、、、摇蚊摇蚊摇蚊摇蚊

萝卜螺萝卜螺萝卜螺萝卜螺

1.6 The ecosystem degradation of Lake Erhai is moderate, which is

the key time to prevent degradation

Nutrition increased + foreign driving (water)

Aquatic plant degradation +

phytoplankton growth

Decline of ecosystem

stability

Oligotrophic

eutrophication

Grass clearly water

Algae Turbid water

early stage of eutrophication

Grass-algae coexistence

Fish structure change largely

AlgaeGrass


1.7 Realization of Erhai Lake ecosystem (improving the habitat is the

premise of ecological restoration)

Water quality is generally good ( ⅡⅡⅡⅡ-ⅢⅢⅢⅢ), but the ecological system has undergone great changes, control loading , restoration of aquatic vegetation, fish ecology

regulation (optimization adjustment of fishery structure), improving habitat is the key measures of ecosystem restoration of Lake Erhai

The fish structure regulation, restore native fish, adjustment of food chain structure, algal

control

The fish structure regulation, restore native fish, adjustment of food chain structure, algal

control

Restoration of aquatic plants (submerged)

(water quality improvement,)

Restoration of aquatic plants (submerged)

(water quality improvement,)

algal bloom Emergency treatment

algal bloom Emergency treatment

phytoplankton

fishAquatic plant

Overlying water

pollution

sediment

Outline

鄱阳湖主要生态环境问题鄱阳湖主要生态环境问题鄱阳湖主要生态环境问题鄱阳湖主要生态环境问题2 Analysis of Lake Erhai aquatic plant degradation

Community structure of the submerged vegetation of Lake Erhai is simplification and serious degradation.

The central platform disappeared, lake bay area shrinking. The plots of submerged vegetation area is about 8Km2.

2000 year ago 2006 year

Distribution of submerged vegetation in Lake Erhai

2.59

1.81

1.04

0.83

0.99

0.85

1.81

11 2 2

3

3

4

4

5

6

6

金鱼藻+微齿眼子菜微齿眼子菜

金鱼藻+微齿眼子菜+光叶眼子菜

微齿眼子菜

马来眼子菜+牛叶眼子菜

苦草

2.1 Light compensation depth of Lake Erhai was reduced near 2000.

The aquatic plants in central platform was disappeared by weak

light stress.

2. Analysis of Lake Erhai aquatic plant degradation

2.2 Reason of aquatic plants degradation- relationship between aquatic plants and light compensation depth (depth)


biomass

Water level

Increas

海潮湾

0

5000

10000

15000

20000

6月 7月 8月 9月 10月 11月

时间

生物量（g FW/m

2

)

现现现现

场场场场

试试试试

验验验验

区区区区

Waterlevel

biomass

2.3 Degradation reason-The distribution of submerged macrophytes in Lake Erhai was decided by light intensity vertical distribution

The water level is higher in spring, the weak light, delaying the submerged vegetation recovery; summer low transparency is insufficient to inhibit the growth and distribution

of Submerged Macrophytes

y = -0.0159x + 0.0661

R2 = 0.5299

-0.2

-0.1

0

0.1

0.2

0 2 4 6 8

水深(m)

RGR(d

-1)

Different depth of water pots experiment

light compensation depth 相对生长率

y = 100e

-1.47x

y = 100e

-0.66x

y = 100e

-0.908x

0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5 6 7

水深（米）

光照百分比（%）

y = 100e

-1.47x

y = 100e

-0.66x

y = 100e

-0.908x

0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5 6 7

水深（米）

光照百分比（%）

12月5.0m9月3.1m 3月6.9m

光补偿点

3月

9月

12月


Seed bank-other way of aquatic plant restoration ?

调查区域调查区域调查区域调查区域

Seed germination experiment

Erhai seed bank species

The platform of seed bank species

轮藻轮藻轮藻轮藻黑藻黑藻黑藻黑藻金鱼藻金鱼藻金鱼藻金鱼藻

黄丝草黄丝草黄丝草黄丝草菱菱菱菱马来眼子菜马来眼子菜马来眼子菜马来眼子菜

共有共有共有共有10101010科科科科15151515属属属属19191919种种种种

严格意义上的水生植物严格意义上的水生植物严格意义上的水生植物严格意义上的水生植物12121212种种种种，，，，

其余其余其余其余7777种为湿生种为湿生种为湿生种为湿生

平均密度为平均密度为平均密度为平均密度为：：：：159.58159.58159.58159.58颗颗颗颗////㎡㎡㎡㎡

ⅠⅠⅠⅠ

ⅡⅡⅡⅡ

ⅢⅢⅢⅢ

Seed bank is not suitable as a major means of

aquatic plant recovery

Most seeds buried deeper

Anaerobic environment ,reduce the seed

vigourPlant debris hinder seed germination

0

50

100

150

200

250

300

密度

（粒

/平

方米

）

北部

中部

南部

西岸湖心东岸

湖

心

平

台

植

被

消

失

湖

心

平

台

植

被

消

失

湖

心

平

台

植

被

消

失

湖

心

平

台

植

被

消

失7

年年年年

2.4 The current condition is not suitable for the restoration of submerged plant seed bank in Erhai

Seed bank-other way of aquatic plant restoration ?

TSIm

30

50

100

Oligotrophication Mestrophication Eutrophication Heavily

Water quality（Ⅱ-Ⅲ Class）

Algae Aquatic plants

fish et al

How to realize the Lake Erhai ecological system-very special ?

3. Focused question

Early stage of eutrophication� Mestrophication: Water quality Ⅱ to Ⅲ

� Eutrophication: N, P high in sediment/ from Algae, aquatic

pant; Fish et al.,

1. Algal bloom Risk prediction and bloom control In Lake

Erhai (or Yun-gui plateau lakes, regional problem?)

What is the problem ?

Biomass of algae in Erhai Lake, 2009

Lake distribution in Yun-gui plateau

Content and distribution of N and P in Lake Dianchi and Erhai sediments

2. How to control the release of N and P from sediment ?Dredge, cover, ecological restoration by aquatic plant, chemic fixation, or other?

What is the problem ?

Nitrogen

Nitrogen

(3) How to protecting biological diversity????

(2) How to cleaning Low

pollution water in lakeside? (1) How to planning land in lakeside ?

3. Watershed pollution control and ecological restoration

What is the problem —from the point of watershed ?

Lake Erhai

the level of the watershed is the level of water quality

What is the new national strategy ? The lake with good water quality should be protected preferentially.

The lake with good water quality should be paid more attention by government.

Lake Dianchi

What is national strategy —from the point of Economy ?

Polluted lake

Lake Erhai

Good water quality

that is the national strategy .

This is the very important adjustment of our national lake protection strategy. The fact is that this work was promoted by our research , about 300 lakes with good water quality will be protected in the future ten years.

Thank you for your attention!

Lake ecological restoration is our dream ?

Nature Lake is our dream!

evolution of lake erhai ecologiecal system in china...evolution of lake erhai ecologiecal system in...

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