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
1. Overview of Lake Erhai ecological environment
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. Overview of Lake Erhai ecological environment
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
1. Overview of Lake Erhai ecological environment
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
1. Overview of Lake Erhai ecological environment
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. Overview of Lake Erhai ecological environment
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)
2. Analysis of Lake Erhai aquatic plant degradation
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
2. Analysis of Lake Erhai aquatic plant degradation
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!