THE EUTROPHICATION AND PHYTOPLANKTON BIODIVERSITY ...

THE EUTROPHICATION AND PHYTOPLANKTON BIODIVERSITY
OF SOME LAKES IN HANOI, VIETNAM
Le Thu Ha
Faculty of Biology, Hanoi University of Sciences, Vietnam National University, Hanoi
Abstract
The five small lakes such as: Thanh Nhan, Ba Mau, Phuong Mai, Giam and Hai Ba
Trung, have been in the eutrophic level. The five large lakes such as: Xa Dan, Giang Vo,
Thanh Cong, Thien Quang and Ngoc Khanh have been in the mesotrophic level
Results of phytoplankton surveys, using only the criteria of presence or absence are
shown that: Thanh Nhan lake has 39 species and sub-species of algae and Cyanobacteria
Ba Mau lake has only 9 species belonging to 3 classes. The dominate of Euglenophyta
shows that water in Ba Mau lake is enrichment nutrients. Xa Dan lake has 10 species and
sub-species. Phuong Mai lake is in the algae blooming period by 10 species belonging to
Chlorophyta, Euglenophyta and Cyanobacteria. Microcystis aerugiosa is the main
component contributing to the algae blooming state in Giam Lake. Giang Vo and Ngoc
Khanh lakes both have 24 species with fairly similar composition of species. Chlorophyta
and Euglenophyta are seen in both lakes, especially representatives of Scenedesmaceae
family and Phacus genus. 40 species were recorded in Thanh Cong lake and 35 species were
recorded in Thien Quang lakes. Hai Ba Trung lake has 65 species.
1. Introduction
It is not by chance that Hanoi is referred to as “Lake City”. Throughout the ups and
downs in different periods of its history, the number of lakes in Hanoi has changed. As the
city becomes more urbanized, more land is required for the development of roads and
buildings. However, Hanoi today still has a large number of large lakes, among which 24
lakes in the urban Hanoi make up the total area of 647,55 ha, more than 10% of the total
area of the urban Hanoi.
In recent years, the speed at which the economy has developed is relatively fast.
Besides the advantages, the problems caused by this economic development have led to
many consequences, one of which is the alarming pollution level of the lakes. Most of them
are “enrichment nutrients”, causing the decline of the water quality, as well as the ecology
and biodiversity.
*Address for correspondence.
E.mail: lethuha17@yahoo.com. Tel: 04.5572605. Fax: 04.8582069

2. Methods
Samples were collected in 2006, 2007 and 2008 from 10 lakes in Hanoi (Vietnam),
including Thanh Nhan, Ba Mau, Phuong Mai, Xa Dan, Giang Vo, Giam, Thanh Cong, Hai
Ba Trung, Thien Quang and Ngoc Khanh.
Parameters of the water quality, including nine variables (temperature, pH,
turbidity, dissolved oxygen-DO, biological oxygen demand-BOD5, chemical oxygen demand-
COD, NH4, NO3, PO4). were measured by TOA, MERK and BOD-System OxiDirect
equipments at laboratory of Ecology and Environmental Biology, Faculty of Biology, Hanoi
University of Sciences [5].
Algae samples were collected by phytoplankton net N o64 and Zooplankton samples
were collected by zooplankton net N o5. All samples were kept in 4% formaldehyde solution
and analyzed at the laboratory of Department of Botany and Microscope Laboratory and
the laboratory of Department of Zoology, Faculty of Biology, Hanoi University of Sciences
[1,2,3,4].
3. Results and Discussion
3.1. Assessment of water quality
The ranges of values obtained at the sampling sites during the physic-chemical surveillance
programme are shown in table 1.
No Lakes
1 Thanh
Nhan
Table 1. Means of water quality parameter values of the lakes
Tem.
( oC)
pH
Tub.
(mg/l)
DO
(mg/l)
BOD5
(mg/l)
COD
(mg/l)
NH4 +
(mg/l)
NO3 -
(mg/l)
PO4 3-
(mg/l)
28.9 8.0 - 8.5 4 - 10 3.2 - 5.6 36 - 43.5 100 - 112 3 - 10 7 – 10 1.25 - 5.0
2 Ba Mau 28.5 7.6 - 7.9 78 - 101 1.0 - 3.0 77 - 87 97 - 104 8 - 10 3 – 5 7.3 - 10
3 Phuong
Mai
28.7
7.4 - 8.1
31 - 57
0.5 - 10.8 73 - 84 131 - 145 7.5 - 10 2 – 3 5.4 - 10
4 Giam 28.5 7.8- 8.0 35 -54 2.53 – 3.7 65.3 - 74.0 112- 139.2 3.7 - 5 1 - 2.2 2.5 – 5.2
5 Giang Vo 29.8 7.9 - 8.6 4 - 9 3.7 - 9.2 27.6 - 29 134 - 156 7 - 10 2 – 10 0.5 - 1.2
6 Ngoc
Khanh
30.4 7.8 - 8.5 7 - 13 4 - 10.3 24.8 - 30 96 - 102 8 - 9 30 – 40 3.2 - 5
7 Xa Đan 29.3 7.7 - 8.3 8 - 12 2.9 - 6.4 34.5 - 37.5 88 - 139 5 - 8 15 – 20 3.2 – 4.2
8 Thanh
Cong
9
Hai Ba
Trung
10 Thien
Quang
24 8.0 - 8.7 2.0 - 4.0 9.5 - 11.9 19.8 - 27.3 32 – 52.16 4.2 - 6.1 6.8 – 10.2 0.5 – 1.3
24.5 7.4 - 7.8 8.0 - 10.0 3.3 - 6.0 29.0 - 35.0 45.0 - 60.0 7.3 - 9.6 15 – 20.1 1.6 – 2.8
24.5 8.5 - 9.0 3.0 - 8.0 8.1 - 11.7 16.4 - 24.0 34.4 - 45.3 3.5 – 4.9 10 – 14.2 0.2 – 0.9
TCVN 5942 [5] 9.0 80 > 2.0 < 25.0 < 35.0 1 15 1
Remarks on the characteristics of 10 lakes analyzed based on the data in table 1:

- The five small lakes such as: Thanh Nhan, Ba Mau, Phuong Mai, Giam and Hai Ba Trung,
have been in the eutrophic level. All these lakes are received domestic sewage and storm
drainage without treatment.
- The five large lakes such as: Xa Dan, Giang Vo, Thanh Cong, Thien Quang and Ngoc
Khanh have been in the mesotrophic level. Because these lakes received only storm
drainage, not received domestic sewage.
- The DO values of all the eutrophic lakes were lest than 4.0mgl -1. The DO values of all the
mesotrophic lakes were higher than 6.0mgl -1.
- The BOD5 values ranged from 19.8mg l -1 (Thanh Cong lake) to 87.0mg l -1 (Phuong Mai)
- The lowest COD values were recorded in Thanh Cong lake. COD concentration was 32mg
l -1. And the highest COD values were recorded in Giang Vo lake. COD concentration was
156mg l -1.
- The high concentration of NH4-N and PO4 -P in water were recorded in the eutrophic lakes.
3.2. Composition of Algae, Cyanobacteria
Results of phytoplankton surveys, using only the criteria of presence or absence are
shown in table 2. One hundred thirty nine species and subspecies of phytoplankton were
recorded. They belong to 5 classes, they are Cyanobacteriophyta, Bacillariophyta,
Cryptophyta, Euglenophyta and Chlorophyta [2,3].
Table 2. Species composition of Algae and Cyanobacteria
of the sampling lakes in Hanoi
No Species Lakes No Species Lakes
Cyanobacteriophyta Chlorophyta
1 Oscillatoria homogenea Frộmy
1,4,6,
9,10
73 Chlamydomonas chrysomonadis 8
2 O. brevis (Kuetz.) ex. Gom. 2,4 74 Cladophora crispata 9
3 O. rupicola Hansg. 1,7 75 Closterium parvulum Nag. 9
4 O. formosa Bory ex. Gomont 3 76
Crucigenia tetrapedia (Kirchn) W.et
W
1,8,9,10
5 O. curviceps C.AG.ex Gom. 8 77 C. fenestrata (Schmid) Schmidle 7
6 O. chlorina 8 78 C. retangularis 1,6,7
7 O. irrigua 9, 10 79 C. quadrata Morren. 1,6,7,9,10
8 O. tenuis AG. ex Gom. 8, 9 80 C. cambricum var. intermedium 1
9
Spirulina platensis (Nordst.)
Geitl.
2 81
10 S. hanoiensis Duong. 10 82
11 S. major Kuetz. ex Gomont 10 83
12 Lyngbya circumcreta G.S.West 1 84
13 L. aerugino-coerulea Kuetz. 1 85
14 L. sp.1 1,4 86
Scenedesmus acuminatus var.
biseratus Reinsch
S. acuminatus (Lagerh.) Chod. var.
acuminatus
S. quadricauda (Turp.) Brelis var.
vesiculosus
S. arcuatus (Lemm.) Lemm. var.
arcuatus
S. bicaudatus (Hanag.) Chod. var.
bicaudatus
S. bijugatus (Turp.) Kuet. var.
bijugatus
1,3,6,7,8
1,3,6,7
7
1
1,6,8,9,10
1,6,7,8,9

15 L. sp 2 6 87
16 Rivularia planctonica Elenk. 1 88
17
Merismopedia minima G.
Beck.
1,3,4,6,7,
9,10
S. bijugatus var. alternans
(Reinsch) Hangg.
S. quadricauda (Turp.) Brelis var.
quadricauda
89 S. denticulatus var.linearis Hansg. 1,9
1,6,7,9
1,6,8,9
18 Microcystis aeruginosa Kỹtz. 2,5,9 90
S. obliquus Kuetz. var. alternans
Christ.
7,8,9
19
M. pulverea f. minor (lemm.)
Hollerb
1,6,8,9,10 91
S. obliquus (Turp.) Kuetz. var.
obliquus
3,8,9
20 M. elegans A. Br. 9 92
S. acuminatus (Lagerh.) Chod. var.
acuminatus
8,9,10
21 M. punctata Meyen 8, 9, 10 93
S. acuminatus (Lagerh.) Chod. var.
elongatus
9
22
Gloeocapsa minuta (Kutz.)
Hollarb. Ampl.
8, 9, 10 94
S. bicaudatus var. intermedius
(Chod.) Ergashev
8
Bacillariophycophyta 95
S. bicaudatus var. skabitschevskii
(Skabitsch.) Ergashev
9
23 Cyclotella sp. 4,6,7 96
S. denticulatus Lagerh
var.denticulatus
9
24 Navicula subtilissima Cl. 1,7 97 S. ellipsoideus Chod. 9
25 N. sp. 6 98 S. hortobagyi (Hortob.) Ergashev 9
26 Cymbella ventricosa (Kỹtz.) 6,10 99
S. quadricauda var. abundans
Kirchn.
9,10
27 Cymbella affinis Kutz. 8 100 Oedogonium sp 1,4,7,8,9,10
28
Gomphonema angustatum
( Kỹtz.) Rabenh.
9,10 101 Hyaloraphidium contortum 2
29 G. parvulum (Kutz.) Grun. 8,10 102 Tetraëdron constrictum 7
30
G. quadripunctatum (Ostr.)
Wisl.
8, 10 103 T. lunula 3
31 G. olivaceum (Lyngb.) Kutz. 8,10 104 T. trilobulatum 1,8
32 G. tergestinum (Grun.) 10 105 T. caudatum 9
33 Navicula confervacea Kỹtz 9,10 106 T. minimum 9
34 N. cryptocephala 10 107 T. reticulatum (Reinsch.) Hansg. 9
35 N. gracilis Ehr. 9,10 108
T. trigonum (Naeg.) Hasnsg. var.
trigonum
9
36 N. tuscula (Ehr.) Grun. 10 109 T. triangulare Korsch. 10
37 N. exigua (Greg.) 8 110 Tetrastrum heteracanthum 9
38
Pinnularia interrupta f. minor
Boye P.
8 111
T. staurogeniaeforme (Schroed.)
Lemm.
39 Stauroneis anceps Ehr. 10 112 Ankistrodesmus gracilis 1
40
Hantzschia amphioxys (Ehr.)
Grun. var. compacta Hust.
10 113 A. bibraianus (Reinsch.) Korschik 7,10
41
Nitzchia gracilis var. capitata
Wisl. et Poretzky
8 114 A. acicularis var. acicularis 1
42 Nitzchia sublinearis Hust. 10 115 A. acicularis 10
43
Achnanthes gibberula Grun.
var. interrupta
8 116 A. angutus (Bern.) Korschik. 9
Cryptophyta 117 Hyaloraphidium curvatum Korsch 8,9
44 Cryptomonas ovata 6,7,8 118 Cladophora sp. 1,4,7,8,10
45 C. erosa 1,8,10 119 Coelastrum microporum Naeg. 1,5,6
46 C. sp1. 8 120
Pediastrum tetras (Ehr.) Ralfs var.
tetras
1,6,9
47 C. sp2. 10 121
P. tetras var. tetraodon (Corda)
Rabenh.
1,8,9
Euglenophyta 122 P. duplex Meyen var. duplex 1,8,9
48 Euglena splendes Dang. 3,7 123 P. duplex var. reticulatum Lagerh 1,9
9

49 E. elastica Prescott 2 124
P. simplex var. duodenarium
(Bailey) Rabenh.
1
50 E. viridis Ehr. 1,8 125
P. biradiatum var. longecornutum
Gutw.
9
51 E. oxyuris Schmarda 2 126
P. boryanum (Turp.) Menegh. var.
boryanum
9
52 E. sociabilis 6,9 127
Schroederia spiralis (Printz.)
Korchikow
8,9,10
53 Euglena acus 9 128 Staurastrum limneticum Schmidle 1
54 E. acutissima 9 129
Actinastrum hantzchii Lagerh. var.
hantzchii
1,3,5,6,7,8,9
55 E. caudata 9 130 Chlorella vulgaris Beijerinck 1,3
56 E. minima 9 131 Golenkinia pancispina 8
57 E. polymorpha Dang. 8 132 Trebouxia arboricola Puymali 10
58 E. proxima 9 133 Dictyosphaerium pulchellum Wood. 9
59 E. rostrifera n. sp. 9 134 Franceia ovalis (France) Lemm. 9
60 E. sp. 9 135 Euastrum sp. 9
61 Phacus longicauda 1,9 136 Cosmarium phaseolus Breb. 9
62 P. longicauda f. curta Lefevre 2 137
Kirchneriella contorta (Schmidle)
Bohlin
63 P. tortus (Lemm.) Swin. 2 138 K. lunaris (Korchn.) Moebius 9
64
P. hispidulus f. suecicus
(Lemm.)
65 P. pleuronectes (Ehr.) Duj. 6
66 P. mentaweiensis Conrad 7
67
P. platalea var. major de
Poucques
68 P. contortus Bourr. 1,6,7
69 P. acuminata 8,9
70
Lepocinclis fusiformis (Carter)
Lemm.
2
71 Lepocinclis ovum 9
72 Trachelomonas volvocina Ehr. 1,3,6
shown that:
6,7 139 K. obesa (West) Schmidle 9,10
7
8,9
1-Thanh Nhan; 2-Ba Mau; 3-Phuong Mai; 4-Xa Đan; 5-
Giam;
6-Giang Vo; 7- Ngoc Khanh; 8-Thanh Cong, 9-Hai Ba
Trung;
10-Thien Quang
Results of phytoplankton surveys, using only the criteria of presence or absence are
- Thanh Nhan lake has 39 species and sub-species of algae and Cyanobacteria. It has
Chlorophyta that is dominated by families of Scenedesmaceae and Hyrodictyaceae.
- Ba Mau lake has only 9 species belonging to 3 classes. The dominate of Euglenophyta
shows that water in Ba Mau lake is enrichment nutrients.
- Xa Dan lake has 10 species and sub-species. Phuong Mai lake is in the algae blooming
period by 10 species belonging to Chlorophyta, Euglenophyta and Cyanobacteria.
- Microcystis aerugiosa is the main component contributing to the algae blooming state in
Giam Lake. It produces microcystin, the most common in Microcystis genus. It is a poison
that can prevent the activities of enzyme protein phosphatase.
- Giang Vo and Ngoc Khanh lakes both have 24 species with fairly similar composition of
species. Chlorophyta and Euglenophyta are seen in both lakes, especially representatives of
Scenedesmaceae family and Phacus genus.

- 38 species were recorded in Thanh Cong lake and 35 species were recorded in Thien
Quang lakes.
- Hai Ba Trung lake has 65 species. The dominate of Chlorophyta shows that water in Hai
Ba Trung lake is enrichment nutrients.
Acknowledgment
We thank Bui Thi Hoa for kind help in sampling, Nguyen Thuy Lien for indentifycation and
her helpfulcomments of phytoplankton diversity. This work was supported by the QT 05-24
project (Vietnam National University)
Reference:
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Hanoi, 1996 (Phân loại Vi khuẩn lam ở Việt Nam).
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reproduction), Prentice- Hall, INC., Englewood Cliffs, New Jersey 07632, 1978.
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London, 1968.
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