Viet Nam National Mekong Committee Environmental Program. Draft report on Review Biological Assessment of Freshwater Ecosystems in Viet Nam

Viet Nam National Mekong Committee Environmental Program Draft report on Review Biological Assessment of Freshwater Ecosystems in Viet Nam Prepared for VNMC Pham Van Mien National Expert January 2002 1

Table of content CHAPTER 1 INTRODUCTION... 3 CHAPTER 2. THE INLAND WATER BODIES OF THE MEKONG RIVER BASIN IN VIETNAM... 5 a. The Dien Bien waterbody... 5 b. The West Thua Thien Hue water bodies... 5 c. The Tay Nguyen highland waterbodies... 5 d. The Mekong Delta in Vietnam... 5 CHAPTER 3. FINDINGS AND OBSERVATIONS OF FRESHWATER ECOSYSTEM OF THE MEKONG RIVER BASIN IN VIETNAM... 7 a. General... 7 b. The impact of socioeconomic activities on the ecosystem of water bodies in Mekong Delta of Vietnam.... 7 CHAPTER 4. INVENTORY OF THE PAPERS, REPORTS ON BIOLOGICAL MORNITORING AND RESEARCH OF FRESHWATER ECOSYSTEMS OF MEKONG RIVER BASIN IN VIETNAM... 12 CHAPTER 5. LIST OF GOVERNMENTAL AGENCIES AND STAFF EXPERIENCING IN BIOLOGICAL MONITORING AND ASSESSMENT... 16 CHAPTER 6 BASIC CHARACTERISTICS OF THE FRESHWATER ECOSYSTEM OF THE MEKONG RIVER BASIN IN VIETNAM... 17 a. Ecosystem of inland water bodies in Mekong Delta of Vietnam.... 17 b. Migrated phenomenon of marine originated fauna into inland cover the whole canals and rivers in Mekong Delta of Vietnam.... 18 c. Topographic structure of Mekong Delta of Vietnam, there are large wetland areas of acid sulfate soil... 19 d. Ecosystem of Tay Nguyen Highland water bodies.... 20 e. Ecosystem of water bodies in the West Thua Thien Hue region... 22 g. Eecosystem of Dien Bien water bodies.... 23 h. The zoogeography location of these water bodies of Mekong Delta in Vietnam. 24 CHAPTER 7. REVIEW AND ASSESSMENT OF THE MRB FRESHWATER ECOSYSTEMS IN VIETNAM... 25 CHAPTER 8. CONCLUSIONS AND RECOMMENDATIONS... 30 2

CHAPTER 1 INTRODUCTION 1.01 According to the Contract No. PPOQ-159 by the Mekong River Commission, dated November 23 rd, 2001 as well as the request from Vietnam National Mekong Committee, dated on December 5 th, 2001, this report prepared by a Local Freelance Expert who have been joint the research and monitoring activities on biology for 40 years. 1.02 The main objectives of the study are to: Review past and present research and monitoring activities in biological assessment of freshwater ecosystem in Vietnam basing on the attention to the methods, activities, resources and skills. List data, reports as well as local experts concerning the activities on monitoring and research of freshwater in Vietnam. Find and observe during the reviews of the specific studies on the freshwater ecosystem. The main findings focused on the fields of: + Basic characteristics in every freshwater regions of the Mekong River Basin belonging the Vietnam areas + Relation between the freshwater ecosystems in Vietnam and the neighboring regions of the Mekong River Basin through define of zoogeographic locations of those regions. + Changes of inland freshwater ecosystems of Mekong Delta in Vietnam territory caused by the social- economic development activities. 1.03 The report has been prepared based on the following methodology and approach : To collect and inventory the documents on the restricted distribution invertebrate of the landscapes and geographic regions such as Crustacea, Decapoda, Copepoda, Calanoida, Mollusca. In fact, it is the results based the taxonomy studies by the European Experts working in Vietnam. To Analyze, review and evaluate as well as generate the results from the documents concerned that have been prepared by the Vietnamese Experts since 1960 up to now. Consult and compute with the Experts from line-agencies as well as the individual Experts such as Prof. Dang Ngoc Thanh of the Hanoi University, the others Experts from Hue University and Cantho University and the Natural Science University working together at the research carried out in the North Vietnam, Thuathien Hue, Tay Nguyen, Mekong Delta of Vietnam. 3

1.04. The study has been concentrated on the freshwater ecosystem in the Mekong River Basin belonging to the Vietnam areas only. 1.05 The structure of the report includes 8 chapter in which Chapter 2 devoted to inland water bodies in Vietnam. Chapter 3 mentioned about the findings and observations. Chapter 4 inventoried the papers, reports, studies concerning the research and monitoring activities of freshwater ecosystem in Vietnam. Chapter 5 listed the Government Agencies as well as the Staff who are experienced in doing monitoring and research in biology in Vietnam. Chapter 6 presented the characteristics of the freshwater ecosystem of the Mekong River Basin in Vietnam. Chapter 7 assessed and reviewed the freshwater ecosystem in Vietnam and Chapter 8 showed the conclusions and recommendations. Besides, the Annexes and Maps also enclosed the report. 4

CHAPTER 2. THE INLAND WATER BODIES OF THE MEKONG RIVER BASIN IN VIETNAM 2.01 The inland water bodies locate in Vietnam territory belonging to the Mekong River Basin include 4 regions: Dien Bien (Lai Chau Province), A Luoi (Thua Thien Hue Province) The Side of West Truong Son, Tay Nguyen Highland and the Mekong Delta of Vietnam.. The Dien Bien waterbody 2.02 The water bodies of Dien Bien belong to the Mekong River Basin consist of Nam Rom River, tributaries, reservoirs, fish ponds and rice fields. In the history of Dien Bien formation, it have not yet appeared the water bodies of national lake form, but after 1960, reservoirs have constructed. 2.03 Geographic locations of the water bodies located in the West North regions and the North Central of Vietnam, which belong to the Northern climate region The West North climate region with the specific characteristics of winter season character red by less cold and dried whole the season; summer season very hot and coming early; a little rain. In Dien Bien, the yearly average rainfall is around 1,567 mm. b. The West Thua Thien Hue water bodies 2.04 The water bodies in the West Thua Thien Hue region located in the watershed between the West Truong Son and the East Truong Son include rivers, streams flow Xe Bang Hien River, which discharges into the middle Mekong River in Lao. For that reason, the running water is the basic characteristic of water bodies in this area. In A Luoi (Thua Thien Hue), many aquaculture ponds have been dug by the local people. 2.05 Geographic location: These water bodies in the West North and the North Central of Vietnam, belong to the climate region of the East Truong Son Binh Tri Thien with the basic characteristics are the strong weather varies with the cold and humid winter season; the summer is hot, dried and much rain. The rainy season begin and finish lately, the rainfall occurs the concentration in two months of October and November. c. The Tay Nguyen highland waterbodies 2.06 The Tay Nguyen plateau is mountain areas and plateaus in the West side of Truong Son range, it belongs to the geographic region of the South Central and the South of Vietnam. 2.07 The Tay Nguyen plateau belongs to the climate region of the South Vietnam The Tay Nguyen climate region with the specific characteristics of temperature regime very temperate: the soft sunlight summer, the cold winter but not too cold as the mountain areas of the North Vietnam. The yearly average rainfall is so high from 1,852 to 2,447 mm. The dry season is blazing hot and length. 2.08 The water bodies in this region include rivers as Po Co, Sa Thay, Sre Pok, Ia Leo. Lakes are originated from volcano (Bien Ho Pleiku), river (Lac lake Dak Lak), and other reservoirs such as Dak Uy, Ialy have built in recently years,. d. The Mekong Delta in Vietnam 2.09 The Mekong Delta of Vietnam includes two major branches that are the Mekong (Tien) and Bassac (Hau) of Mekong River, tributaries and the interacting canal network connecting with Vaico and Dong Nai river systems. In the formation history, according some 5

specialists said that, the Vaico River was a branch of Mekong River, but in the tectonics process, it was separated to the Mekong river system and joined with the Dong Nai river system. 2.10 No natural lakes and large reservoirs appeared in the Mekong Delta of Vietnam that the water bodies include such as ponds, rice fields, the shallow wet land areas with a lot of aquatic macrophyte. 2.11 Geographic features of the water bodies of Mekong Delta in Vietnam which belong to the climate region of the South Central and South of Vietnam The climate of South Delta region with the yearly average temperature shows little fluctuations (amplitude 3 4 0 C) and high temperature, which has the clearly differentiation in the regime of humidity and rainy suited with the monsoon. 2.12 The basic characteristics of the water bodies in Mekong Delta of Vietnam can be made clearly as: The systems of canals and rivers run across the delta of new tectonics and low plain. The low average slope, from Tan Chau goes toward the sea one-centime length; the slope decreases only one-centime height. Tides have been effected from two directions of the South China Sea and the Thailand Gulf, making the meeting points in the systems of canals and rivers of Mekong Delta of Vietnam, or canals and rivers taken water from two directions (South China Sea and Thailand Bay), have also the meeting points. However, the locations of meeting points have also changed by the water resources development projects. For example, the meeting point changed from the Long My town-let (Can Tho province) to the three-way Vinh Cheo in the Cai Lon river after constructing the Tra Ban Dam. The systems of rivers and canals in the coastal plains are affected by saline water with different levels. By the tectonics in Mekong Delta of Vietnam, which have the large water-logging areas as Dong Thap Muoi, the wet land areas such as the West Hau river, U Minh, with the characteristics of low ph, thick bottom mud of decomposed plants, a lot of aquatic macrophyte, the large difference changes of water levels following seasons. These wet land areas, which have many characteristics of the temporary water bodies. 6

CHAPTER 3. FINDINGS AND OBSERVATIONS OF FRESHWATER ECOSYSTEM OF THE MEKONG RIVER BASIN IN VIETNAM a. General 3.01 The above research situation on inland water bodies ecosystems of Mekong River Basin in Vietnam, shown that: Many hydro-bios organisms have studied a little as insect larva or not yet researched such as Protozoa, Coelenterata, Bryozoa,. About eco-physiology, researchers have only focused to study the breeding objects such as Moina dubia, Macrobrachium rosenbergii (Giant river prawn),. Many hydro-bios organisms have not yet corrected about the classification and identified the natural geography distribution, the landscape geography. Now, the records about the inland water bodies ecosystems of Mekong river basin in Vietnam, which have not yet concentrated, and many specialties agencies have done with different methods. Therefore, the collection and assessment are very difficult. 3.02 The works need to be done including: To consider the overview about aquatic ecosystems in these regions, the collection, evaluation, correction for documents should be done immediately. From above results, to identified the continuously research steps. 3.04 Base on the available sources, however, we can present the basic characteristics on: The characteristics of ecosystems. The quantity structure, the dominant species, the endemic species for every the geographic region, the landscape regions. To identify the relations between the water bodies in Vietnam and the neighboring regions belong to Mekong river basin such as China, Lao, Cambodia, and the North Vietnam. The changes of inland water bodies ecosystems of Mekong river basin in Vietnam caused by the social economic activities. 3.05 In tens of recently years, the economic and social activities have been caused the strong changes for the wetland ecosystems in Mekong delta about geomorphology, hydroregime, flora and fauna resources and biodiversity. b. The impact of socioeconomic activities on the ecosystem of water bodies in Mekong Delta of Vietnam. 7

3.06 As above presented, the inland migrated phenomenon of marine originated species in Mekong Delta of Vietnam is the basic characteristic of this ecosystem. On the other hand, the inland water bodies ecosystems of Mekong Delta in Vietnam is a open ecosystem, but about 20 years recently, the social economic activities in Mekong Delta of Vietnam have evolved following the close ecosystem in tendency, it made the strong changes in the inland water bodies ecosystem. We can show symbol activities: The impact of mangrove deforestation building the shrimp culture extensive. 3.07 At the begin 80 s, when the shrimp price is high in the international market, the trade activities has became effervescent in Mekong Delta of Vietnam. The extensive shrimp culture has developed widely from the inland water areas with low salinity to the coastal waters. The mangrove deforestation has been happened strongly from Ba Ria Vung Tau to Dat Mui (Ca Mau). 3.08 The general characteristics of breeding ponds were the process of the acidification increase, the organic substance deposition, the increase of concentration H 2 S, Al 3+ 2-, SO 4 in the bottom mud. In water layer, the increase of ΣN and the decrease of O 2 have made the development of species Oscillatoria (Cyanophyta), Enteromorpha (aquatic macrophyte) and the biodiversity decrease. (Reports: The records about the environment impact of the shrimp pond constructions in the alluvial ground Dat Mui Ngoc Hien Minh Hai. Doan Canh Pham Van Mien (1992) and The impact of social and economic activities on the biodiversity of mangrove forest in the coastal and estuary areas of the South Vietnam. Pham Van Mien, Do Thi Bich Loc, Vu Ngoc Long, Truong Quang Tam (1993). 3.09 The monitoring results before and after the shrimp pond eradication in the Dat Mui alluvial ground (6/1992, 10/1996, 9/1998) show that after the shrimp pond eradication, this ecosystem has changed the following positive direction in tendency with the decrease of Al 3+, H 2 S concentration in bottom mud. The Zoobenthos in these areas have recovered, and the quantity of Phytoplankton and Zooplankton fauna has distributed more equal in the water bodies comparison with before. 3.10 However, The analyzing results of aquatic flora and fauna composition structure, the quantity and the dominant species, figured that the water quality in the Dat Mui alluvial ground areas have increased the eutrophic level and organic pollution in tendency. 3.11 In fact, the mangrove forests recovery in this area has only developed in surrounding the banks. In ponds, the recovery has happened slowly. Up to now, after 5 years, there are a few mangroves in the old shrimp ponds. Maybe, the decayed mud formation in the bottom mud has been limited the mangrove reforestation. The impacts of forest lake hoà röøng construction. 3.12 After the most serious forest burning (1983), the Ca Mau authority decided to built canals, banks surrounding the sovkhoz such as U Minh I, U Minh II, U Minh III, Vo Doi aimed keeping water for anti-burning in the dry season. These areas are called Forest Lake. 8

3.13 These works have been done in An Giang, Kien Giang, Can Tho, and Dong Thap Muoi, even in Tram Chim Tam Nong National Park (Tam Nong district Dong Thap province). 3.14 The bank construction caused the water bodies pollution because the hydrophyte development such as leaves, pondweed, pondgrass, water hyacinth, waterlily, that have developed strongly, and then it would be died and decomposed making the decayed mud in bottom. The most serious damage, it is a barrier of the fish migrated pass from canals and rivers into the forest caused the white fish lose, there is only the black fish; the decayed mud destroyed the whole of Zoobenthos; in the water bodies, there is only species of Phytoplankton and Zooplankton indicated for the low ph, the saline effect water, and the polluted water as: Phytoplakton: Diatoma hyalinum, Navicula granii, Nitzschia paradoxa, Anadaena affinis, Oscillatoria princeps, Spirogyra hassallii, Phacus curvicauda, Euglena acus, Lepocinclis ovum,. Zooplankton: Trochosphaera solstitialis, Brachionus quadridentatus, Rotaria rotaria, Moina dubia, Moinodaphnia macleayii, Mesocyclops leuckarti, Schmackeria bulbosa, S. speciosa,. 3.15 In 20 samples, there were only 10 species Zooplanton in the field trip (6/1993). In which, the indicators for the low brackish water as Schmackeria bulbosa, Limnoithona sinensis; the low ph water (4,0 5,0) Lecane (Monostyla) bulla, Brachionus quadridentatus; and the eutrophic water Mesocyclops leuckarti, Moina dubia, Polyarthra vulgaris are dominant. 3.16 The habitat has been changed so much as the bird feed source decrease, therefore many bird species have migrated to other areas. This phenomenon has also happened in the Dam Doi bird garden (Ca Mau province). 3.17 Because of waterlogged forest for a long time, the development of planting cajeput is low. When the height of cajeput about 5 m high, it is easy to mass-falling down by strong winds. 2.17 The impact of Forest Lake construction need be considered more other sides as the cajeput eco-physiology changes, the changes of fish and other aquatic fauna and flora because of hydroregime change. The impact of freshwater for Ca Mau Peninsula. 3.19 Over a half of last century, the canal networks have been built in Mekong Delta of Vietnam aimed the agricultural area enlarge, the irrigation and the waterway transportation. In every local areas, they have also constructed the partial freshwater for Cai Nuoc, Dam Doi, Tran Van Thoi, by rainy water. 9

3.20 The freshwater works have reached the noticeable results as the increase of areas and drops, but we need be considered the agricultural and environmental questions in new ecology conditions as following: The decrease of salinity in the inland water bodies. The increase of organic substance deposit. The development of macrophyte as Ceratophullum, Myriophyllum, Nympha sp., floating fern, water hyacinth It would be died and decomposed in bottom mud caused the mud and water environment pollution. 3.21 The results of monitoring time (3/1993) in the Quan Lo Phung Hiep freshwater area, showed that in the high saline water environment as Ninh Hoa Ca Mau (S: 11 22 ), all of the Zooplankton species are the symbol marine and brackish species: Paracalanus parvus, Centropages calaninus, Schmackeria dubia, S. speciosa, Acartia clausi, Euterpina acutifrons,. 3.22 The Zooplankton distribution in the Quan Lo Phung Hiep salinity control areas (Hong Dan, Lang Cham, Ninh Hoa) comparison with Cai Nuoc, Bay Hap, Cua Lon river, Ca Mau point are different so much, it is point out the identical characteristic at the begin of the priod of salinity control. 3.23 The samples collected inner dams in Quan Lo Phung Hiep (12/1997 and 3/1998) figured that, in the rainy season, almost species of Zooplankton are freshwater species; only one species Limnoithona sinensis is typical for the low brackish water (0,3 ). In the dry season (3/1998), the Zooplankton species composition mixed the characteristics between the freshwater and brackish water environment. 3.24 Zoobenthos: Both all the dry and rainy seasons, the marine species are dominant the species composition and the quantity including species of Polychaeta, Isopoda, Amphipoda and Mollusca. The canals in the freshwater areas, only the freshwater species Thiara scabra (Thiaridae) occurs in here. 3.25 Generally, the changes of the hydrobios species composition in the Quan Lo Phung Hiep region have corresponded of salinity changes. The process of salinity control in bottom mud has been happened slower comparison with water layer. 3.26 The general characteristics of the hydrobios development in the freshwater areas and Forest Lake are the abundance and the dominance of the Zooplantkon species composition with the indicator species for the eutrophic environment. The species number and quantity of Zoobenthos decrease strongly in almost these areas. 3.27 The development of Zooplankton in the salinity control Bac Lieu has many similarity points as the salinity control Soc Trang. The status of salinity control in Soc Trang is better than Bac Lieu. 10

The impact of bank construction living together with the flood. 3.28 Recently years, the implementation of living with flood, many local authorities in Mekong Melta have built the flooded prevent banks for the inhabitant areas, the fruit tree gardens, the rice fields, making many the closed ecosystems in the improved areas by Mekong River water. For reason that, hundreds hectar of mango of the Long Vu sovkhoz (Long An) and some other fruit tree gardens were died by waterlogged; the habitat of fish, prawn is limited. In the bank construction areas, the water has receded very slowly, it effected to the new crop. The impact of produce changes from rice field to aquaculture. 2.29 In 2000, in the ecotone areas one of areas, which have happened the strong varies about the salinity and the ecology condition in one year and been carrying out the freshwater project: Tien Giang, Ben Tre, Tra Vinh, Soc Traêng, Bac Lieu, Ca Mau, Kien Giang, and the conflict between the rice plant and the aquaculture have happened strongly. In many areas, local authorities allowed to change from rice field to shrimp culture or a rice crop, one shrimp-breeding season. 2.30 These brackish originated ecosystems have changed to freshwater ecosystem, now it suddenly returns the brackish ecosystem. This event caused the water quality decrease because of the hydrophyte decomposition. The habitat is not stable. The conflicts between rice field and shrimp culture have not yet identified clearly in the ecotone of Mekong delta. 11

CHAPTER 4. INVENTORY OF THE PAPERS, REPORTS ON BIOLOGICAL MORNITORING AND RESEARCH OF FRESHWATER ECOSYSTEMS OF MEKONG RIVER BASIN IN VIETNAM 6.0 The following papers, reports on the biological monitoring and assessment of freshwater can be listed as following: 0. A. Shinota, 1963. The plankton in south Vietnam. 0. B. H. Dussart and D. Delays, 1995. Copepoda. Guides to the Identification of the Macro-invertebrate of the Continental Wates of the World. H. J. F. Dumont: 1 277. 0. Bouvier, E. L., 1925. Crevette de la famille des Atyides Encylopedie entomolologique IV Editem Paul Lecheralier. Paris: 1 365. 0. Dang Huu Dao, 1993. Thematic study on environment impacts Mekong Delta of Vietnam Master Plan (vie/87/031): 1 33. 0. Dang Ngoc Thanh, Ho Thanh Hai, 1998. Review on the taxonomy and geographical distribution of two species of Diaptomidae Crustaceans (Copepoda Calanoida) from freshwater of Vietnam. Journal of Biology. 20 (2): 1-5. 0. Dang Ngoc Thanh, 1998. Freshwater prawn genus Macrobrachium Bate, 1868 (Palaemonidae) from the Southern part of Vietnam. Journal of Biology. 20 (3): 1 3. 0. Darren C. J. Yeo and Nguyen Xuan Quynh, 1999. Description of a new of Somannithephusa (Decapoda Brachyura. Parathephusidae) from Vietnam. Crustacea 72.3: 339 349. 0. Dang Ngoc Thanh Thai Tran Bai Pham Van Mien, 1980. Classification of Freshwater invertebrate Zoology in the North Vietnam. The Science and Technology Publisher. 1 573. 0. Dang Ngoc Thanh, 1980. Freshwater invertebrate Zoology in the North Vietnam. The Science and Technology Publisher. 1 463. 0. Dang Ngoc Thanh, 2000. Palaemoninae (Palaemonidae) of Decapoda Macrura. The Fauna Vietnam (Published not finish): 1 36. 0. Dang Ngoc Thanh, 2000. 12

Parathelphusidae, Potamidae of Decapoda Brachyura. The Fauna Vietnam (Published not finish): 37 63. 0. Dinh Khac Thang, 1978. The studies contribution of Copepoda in the South Vietnam. The graduated subject The Biology Falcuty Hue University. 1 73. 0. Doan Canh, Nguyen Van Tuyen, Tran Truong Luu, 1986. The basic investigation of biology resources in Dong Thap Muoi. The State program 60 02: 1 66. 0. Duong Duc Tien, 1987. The freshwater algue Vietnam Chlorocociales. The Agriculture Publisher. 0. Hoang Bich Mai, 1978. The studies contribution of Amphipoda, Isopoda, Tanaidacea in the South Vietnam. The graduated subject The Biology Faculty Hue University. 1 59. 0. Holthuis, L. B. 1950. The palaemonidae The decapoda of the Siboga expedition. PartX: 1 260. Leiden E. j. Brill. 0. Le Tu Trinh and Marion Van Maren, 1991. Environmentally sensitive ecosystems in the Mekong Delta of Vietnam Nedeco. 0. Nguyen Huu Hien, 1971. The studies contribution of Rotatoria in the North Vietnam. The graduated subject The Biology Faculty Hanoi University. 1 88. 0. Nguyen Huy Yet, 1971. The studies contribution of Decapoda Macrura of families Palaemonidae and Atyidae in the North Vietnam. The graduated subject The Biology Faculty Hanoi University. 1 95. 0. Nguyen Thi Duc, 1971. The studies contribution of Oligochaeta in the North Vietnam. The graduated subject The Biology Faculty Hanoi University. 1 113. 0. Nguyen Thi Hoa, 1971. The studies contribution of Gastropoda of families Pilidae, Viviparidae, Bithyniidae in the North Vietnam. The graduated subject The Biology Faculty Hanoi University. 1 61. 0. Nguyen Xuan Quynh, 1971. The studies contribution of Mollusca Bivalvia of family Unionidae in the South Vietnam. The graduated subject The Biology Faculty Hanoi University. 1 120. 0. Nguyen Thi Hien, 1978. The studies contribution of Rotatoria in the South Vietnam. The graduated subject The Biology Faculty Hue University. 1 72. 0. Nguyen Thi Hong Lien, 1978. 13

The studies contribution of Cladocera in the South Vietnam. The graduated subject The Biology Faculty Hue University. 1 56. 0. Nguyen Van Tuyen, 1980. The freshwater algae in the North Vietnam. The doctorate thesis of biology science Hanoi University. 0. Nguyen Van Tuyen, 1980. Les algues d eaux douces des regions de Lan Co (An Cu Tay) et le A Luoi soumises a le larges gandayes d herbicide CT. 10 80. 0. Nguyen Van Xuan, 1981. Palaemoninae (Palaemonidae) of Decapoda Macrura in the South Vietnam. The magazine of Science and Technology HCMC, V (3). 146 152. 0. Nguyen Van Xuan, 1992. Review of Palaemoninae (Crust. Decap. Caridea) from Vietnam Macrobrachium excepted. Zool Med. Leiden. 66 (2) 31. VII: 19 47. 0. Nguyen Van Trong et al, 1984. The characteristics of water environment, hydrobios and fisheries resources in BenTre province. 0. Pham Hoang Ho, 1969. Quelques algues d eau douce de la re gion de Cantho. 0. Pham Van Mien, Nguyen Van Thuong, Truong Thu Khoa, 1985. The investigation of fisheries resources and the characteristics of hydrobios in the inland water bodies of Hau Giang province. The State program 60 02: 1 82. 0. Pham Van Mien, 1995. The characteristics of hydrobios and environment in the Gia Lai water bodies. 0. Pham Van Mien et al, 2001. The researching studies of Bien Ho (Pleiku) ecosystems The studies of protection approaches of the Bien Ho water quality aimed applying water for Pleiku province capital: C 4.1 C. 4.15. 0. Pham Van Mien et al, 2001. The characteristics of water bodies environment in the produce change areas of Dam Doi and Cai Nuoc, Ca Mau province: 1 35. 0. Pham Van Mien, Dao Thanh Son, Nguyen Thi Mai Linh, Pham Anh Duc, 2001. The aquatic flora and fauna in the Dong Thap Muoi wetland The studies of biodiversity changes in Dong Thap Muoi area served for the produce structure changes. The Environment Ministry Department: 150. 0. Pham Van Mien et al, 1999. The water environment and the aquatic flora and fauna in Ca Mau Pennisula The studies of changes of coastal areas in the South Vietnam. The National Centre of Nature Science and Technology: 124. 14

0. Ralf A. M. Brandt, 1974. The non-marine Mollusca of the Thailand. Frankfurt Am Main: 1 423, with 30 plates. 0. The Subinstitute of Hydraulic Scheme II, 1999. The project of development investment of Tram Chim National Park in Tam Nong district Dong Thap province, the period from 1999 to 2003: 20 21. 0. Tran Ngoc Loi, 1969. Described four species of Polychaeta of family Nereidae in Cantho freshwater areas (The South Vietnam). 0. Tran Truong Luu, et al, 1995. The results of water quality, hydrobios and fisheries resources in Long An province 1994 1995: 1 132. 0. Tran Truong Luu, Nguyen Van Trong, Mai Ngu, 1991. Assessment of the present status of aquatic ecological zones in the Mekong River Delta (Vie 87/031). 0. Tu Thanh Dung, 1986. The records of the classification of Amphipoda, Isopoda, Tanaidacea. The graduated subject The Fisheries Department Cantho University. 1-43. 0. Y. Ranga Reddy, 1994. Copepoda: Calanoida: Diaptomidae Guides to the Identification of the Macroinvertebrate of the Continental Wates of the World. H. J. F. Dumont: 1 216. 0. Mekong Delta Master Plan Project, 1993, NEDECO HASKONING, Environmental Profiles (VIE 87/031). 15

CHAPTER 5. LIST OF GOVERNMENTAL AGENCIES AND STAFF EXPERIENCING IN BIOLOGICAL MONITORING AND ASSESSMENT 5.01 The local consultants who have joint, studied or experienced in monitoring and assessment of the biology in the freshwater ecosystem in Vietnam can be listed as bellow: 0. Prof. Dr. PhD. Dang Ngoc Thanh Invertebrate Zoogology The National Centre of Nature Science and Technology. Nghia Do Hanoi. 0. Dr. Ho Thanh Hai Zooplankton. 0. Dr. Nguyen Xuan Quynh Invertebrate Zoogology The Biology Faculty The Natural Science University in Hanoi. 0. Prof. Dr. PhD. Duong Duc Tien Phytoplankton The Biology Faculty The Natural Sicnece University in Hanoi. 0. Dr. Dang Thi Sy Phytoplankton The Biology Faculty The Natural Sicnece University in Hanoi. 0. Hoang Thi Ty Zooplankton The Institute of Fisheries Studies I. Dinh Bang Hanoi. 0. M.sc. Nguyen My Phi Long Phytoplankton The Biology Faculty The Natural Sicnece University in HCMC. 0. M.sc. Nguyen Phi Nga Aquatic Macrophyte The Biology Faculty The Natural Sicnece University in HCMC. 0. Dr. Nguyen Thanh Tung Phytoplankton The Biology Faculty The Natural Sicnece University in HCMC. 0. Duong Ngoc Dung. Zooplankton The Biology Faculty The Natural Sicnece University in HCMC. 0. Pham Van Mien Invertebrate Zoogology The Environement and Sustainable Development. 152 Nguyen Van Thu Dist. 1 HCMC. 0. Pham Anh Duc Zoobenthos The Institute of Tropical Biology. 85 Tran Quoc Toan Dist. 3 HCMC. 0. Nguyen Thi Mai Linh Zooplankton The Institute of Tropical Biology. 85 Tran Quoc Toan Dist. 3 HCMC. 0. Dao Thanh Son Phytoplankton The Institute of Tropical Biology. 85 Tran Quoc Toan Dist. 3 HCMC. 0. Vu Ngoc Long Aquatic Macrophyte The Institute of Tropical Biology. 85 Tran Quoc Toan Dist. 3 HCMC. 0. M.sc. Nguyen Van Thuong Decapoda The Agriculture Department - Cantho University. 0. M.sc. Nguyen Mong Zooplankton The Biology Faculty Hue University. 0. Dr. Ton That Phap Zooplankton The Biology Faculty Hue University, 0. Tran Truong Luu Phytoplankton The Institute of Fisheries Studies II. 16

CHAPTER 6 BASIC CHARACTERISTICS OF THE FRESHWATER ECOSYSTEM OF THE MEKONG RIVER BASIN IN VIETNAM. 6.01 Based on the researching status of inland water bodies ecosystem in Mekong Delta of Vietnam, especially, as our results. We can present the basic characteristics of these ecosystems: a. Ecosystem of inland water bodies in Mekong Delta of Vietnam. The aquatic flora and fauna of inland water bodies in Mekong delta. 6.02 The species of widely distribution include Algae, Protozoa, Rotatoria, Cladocera, Copepoda Cyclopidae, Harpacticoida, Oligochaeta. These organisms have distributed in small and shallow water bodies with many aquatic macrophyte such as ponds, rice fields, wetland areas (Dong Thap Muoi, U minh, The West Hau river region). In the species composition, there are many indicator species for the acid sulfate water. 6.03 The marine species migrated into inland: Polychaeta, Copepoda Calanoida, Coelenterata, Mollusca, Crustacea, (Amphipoda, Isopoda, Tanaidacea, Mysidacea, Decapoda), Prochordata,. These species organisms occur widely in the estuaries and coastal areas of Mekong River and have the relation with the species in Mekong Delta of Cambodia areas: Zooplankton: The species of Copepoda (Diaptomidae and Pseudodiaptomidae) have distributed in the middle and downstream of Mekong River and the South Asia Pseudodiaptomus beieri, Eodiaptomus draconisignivomi, Vietodiaptomus hatinhensis, V. tridentatus, Allodiaptomus raoi, A. mieni, Neodiaptomus malaiindosinensis, Tropodiaptomus vicinus. The species of Palaemonidae: Macrobrachium mekongense, M. lanchesteri, M. pilimanus, M. equidens, M. rosenbergii, M. mirabile, M. sintangense, M. lar, M. idea, Leandrites indicus, Leptocarpus potamiseus, Exopalaemon vietnamicus, Palaemon curvirostris, P. concinnus, P. serrifer, P. pacificus, P. semmelinvckii. The species of Decapoda Brachyura: Somanniathelphusa germaini, S. dugasti, S. neisi, Siamthelphusa beauvoisi, Ranguna cochinchinensis, R. longipes, R. brousmichei, Larnaudia, larnaudia. The species of Mollusca: Gastropoda: Pila ampulacea, Filopaludina (Filopaludina) doliaris, Indoplanorbis exustus. Bivalvia: Scaphula pinna, Pilsbryochoncha exilis compressa, Corbicula blandiana, C. leviuscula, C. castanea. 17

b. Migrated phenomenon of marine originated fauna into inland cover the whole canals and rivers in Mekong Delta of Vietnam. 6.04 In four water bodies regions of the Mekong River Basin in Vietnam territory: Dien Bien, A Luoi, Tay Nguyen plateau and Mekong Delta. Only Mekong Delta of Vietnam has a migrated phenomenon of marine originated species into the inland water bodies. 6.05 The inland migrated phenomenon, which presented in detail in the report Freshwater invertebrate zoology in the North Vietnam (Dang Ngoc Thanh, 1980: 280 289). 6.06 The inland-migrated phenomenon of marine originated species in Mekong Delta of Vietnam is different with other areas such as the North Vietnam about amplitude and intensity. 6.07 In the North Vietnam, the marine originated invertebrate species migrated in inland such as: Nephthys polybranchia, Namalycastis longicirris, Tylorynchus heterochaetus, Caobangia bibeti (Polychaeta), Grandidierella vietnamica, Corophium minutum, C. intermedium, Metoediceropsis dadoensis, kamaka palmata, Hyale hawaiensens, Eohausforius tandeensis, Melita vietnamica, Cyathura truncata, Tachaea chinensis, Apseudes vietnamensis and some species of Copepoda of Centropagidae, Pseudodiaptomidae, Oithonidae (Crustacea), most of above species have only migrated into inland 50 60 km length with sea. The marine originated species migrated the fareast distance into Chi Ne (Boi River - Hoa Binh province) and the Huong barrage of Cau River (Thai Nguyen province) is Nephthys polybranchia. The species Namalycastis longicirris (Polychaeta), Schmackeria bulbosa (Copepoda) can migrate into Hanoi. 6.08 We have studied the inland-migrated phenomenon of marine originated fauna in Mekong Delta of Vietnam from 1985 (The hydrobios characteristics of water bodies in Hau Giang province The State program 60 02). Especially, in the monograph document The classification of Amphipoda, Isopoda, Tanaidacea in the Hau river area (The graduated subject of Tu Thanh Dung Cantho University Lecturer Pham Van Mien) analyzed and evaluated the distribution of marine originated Crustacea into inland above. 6.09 Continuously, we have considered to this problem in the projects such as the landscape ecology project in the Sai Gon Dong Nai river system including Vaico River, The project of environmental change studies in the coastal areas of South Vietnam (Pham Van Mien, 1999), The project of biodiversity studies in Dong Thap Muoi (Pham Van Mien et al, 1999 2001), The project of hydrobios studies served for the produce structure changes in Dam Doi (Ca Mau 1993) and Dam Doi, Cai Nuoc (Ca Mau 2000), the projects of water quality monitoring in the Sai Gon Dong Nai river system and Mekong Delta of Vietnam. 6.10 The characteristics of inland migrated phenomenon of aquatic marine originated species in Mekong Delta of Vietnam: 18

The inland-migrated organisms have the diversity about species composition: Coelenterata, Polychaeta, Copepoda, Mysidacea, Euphaussacea, Decapoda, Mollusca, Echinodermata, Prochordata. The marine originated organisms occur in the whole of downstream areas in the Mekong river basin (from the Vaico river basin to the system of canals and rivers that discharges to the Gulf of Thailand), even many areas far from sea with hundreds of kilometers such as Chau Doc, Tan Chau, Hong Ngu, Tan Thanh, Vinh Hung, nearly the border between Vietnam and Cambodia. Many completely freshwater areas in Mekong Delta of Vietnam, the aquatic flora and fauna composition structure are typical for marine with the appearance of algae species of Bacillariophyta and the Zooplankton species of Copepoda, Isopoda, Amphipoda, Tanaidacea, Decapoda, Polychaeta. These species are dominant both all the species composition and the quantity. 6.11 The flooded season is good conditions for the marine originated species enlarging widely the distribution area toward the North Mekong Delta of Vietnam. 6.12 In the dry season, the acid sulfate water have limited the development and restricted the distribution of aquatic flora and fauna in many areas of Mekong Delta of Vietnam. 6.13 The studies of the inland migrated phenomenon of marine originated species in Mekong Delta of Vietnam, have contributed to the zonation of environment scheme, the ecology zonation, the agriculture forestry fisheries produce scheme and evaluated the change of ecology conditions and the result of salinity control project of saline effect areas. 6.14 Moreover, we have evaluated the impact of coastal-dyke construction project, the flooded drainage project. And the most important question, we identified the ecotone zone An ecozone with the strong varies, the low biology productivity. 6.15 At present, the ecotone zones have happened the conflict between the agriculture produce and aquaculture in Soc Trang, Bac Lieu, Ca Mau, Kien Giang,. It should be corrected the produced zone scheme. c. Topographic structure of Mekong Delta of Vietnam, there are large wetland areas of acid sulfate soil. 6.16 It can be define these wetland waters in Mekong Delta of Vietnam by the characteristics of low ph (ph < 5,5), the indicator animals and dominant species: Phytoplakton: Closterium acutum, Eunotia sudetica, Phormidium tenue,. Zooplankton: Scaridium longicaudum, Brachionus quadridentatus, Lecane (Monostyla) bulla, Latonopsis australis, Ilyocryptus halyi, Alona davidi,. 19

Zoobenthos: Ablabesmyia sp., Clinotanypus sp., Polypedilum sp., Cryptochironomus sp. (Chironomidae Diptera), Digoniostoma siamense (Mollusca Gastropoda, Bithynidae). The quantity of Phytoplankton and Zooplankton are high. Zoobenthos low. 6.17 In dry season, the acid sulfate waters have been considerably enlarged more comparison with rainy season, and many regions as U Minh, Tu Giac Long Xuyen, the South East Dong Thap Muoi are effected by saline water with different level from 1 to 12. In the rainy season, the low ph waters are closed. 6.18 There are many fish species of high quality: climbing perch (Anabas testudineus), snakehead (Ophiocephalus striatus), yellow catfish (Clarias macrocephalus), gourami (Trichogaster pectoralis). Farmers have enlarged the above fish culture in the acid sulfate water areas (Pham Van Mien, 2000 and 2001). 6.19 The canal constructions drained water from Mekong River into the acid sulfate soil of Dong Thap Muoi, Tu Giac Long Xuyen, the West Hau river region made more specific changes for the acid sulfate waters: The indicators and dominant species for the freshwater ecosystem (Hydrocarbonat Carbonat) with the eutrophic water quality in Mekong Delta of Vietnam have enlarged to the code region of Dong Thap Muoi, Tu Giac Long Xuyen, the West Hau river. Phytoplankton: Synedra ulna, Melosira granulata, Surivella robusta, Nitzschia longissigma, Trachelomonas volvocina,. Zooplankton: Polyarthra vulgaris, Trichocerca similis, Thermocyclops hyalinus, Bosmina longirostris, Neodiaptomus malaidosinensis,. Zoobenthos: Corbicula tenuis, C. cyreniformis, C. blandiana (Mollusca Bivalvia). The quantity of Phytoplankton is lower; maybe result from the turbidity higher comparison with the acid sulfate water. The quantity of Zoobenthos is high because of the development of species of genus Corbicula and Oligochaeta. d. Ecosystem of Tay Nguyen Highland water bodies. 6.20 The basic characteristics of Tay Nguyen water bodies ecosystem are the water of lake forms (natural lakes, reservoirs), the sources rivers as Po Co, Ta Ileo, Ia Kroâng Ana flow Xe Xan river, Sre Pok river in Cambodia that located in the elevations from 300 to 1.700 masl., with an average altitude 500 600 masl.. With occurrence of species of Copepoda Diaptomidae is Dentodiaptomus javanus (Gromalicki). 6.21 This species of Copepoda occurs in the Yunnam plateau (China) and the Java island (Indonesia) and the species of Decapoda Macrura Macrobrachium secamanense Dang collected Secaman River (Lao) and Luoi village (Tay Nguyen) in 1974, and the Dang Ngoc Thanh published this species as new taxa for science (Dang Ngoc Thanh, 1998: 1-4). 20

6.22 The running water characteristic of upstream rivers of tributaries Mekong River with the below species Corbicula baudoni (Corbiculidae Bivalvia), Antimelania costula, Thiara scabra (Thiaridae Gastropoda), Tanytarsus sp. (Chironomidae Diptera). 6.23 The eutrophic characteristics of the lake forming water bodies with the species appearance: Phytoplankton: Oscillatoria subbrevis, O. princeps, Melosira granutala, Fragilaria capucina, Euglena acus, Lyngbya limnotica,. With the trophic index of Nygaard: Total Species Cyanophyta+Total species Bacillariophyta Centrales+Total species Chlorophyta) t : > 1 Total species Desmidides 6.24 The Phytoplankton quantity is high. Table: The quantity structure of Phytoplankton in Bien Ho Pleiku (cell/m 3 ). Bien Ho Reservoirs 6/2000 10/2000 6/2000 10/2000 38.500.000 286.000.000 46.750.000 371.500.000 279.000.000 493.500.000 128.500.000 136.500.000 Chroococcus sp. Lyngbya limnetica Lyngbya limnetica Lyngbya limnetica Closterium acutum var. variabile Zooplankton: Polyarthra vulgaris, Brachionus urceus, Mesocyclops leuckarti, Thermocyclops hyalinus, Moina dubia. 6.25 The Zooplankton quantity is high. Table: The quantity structure of Zooplakton in Bien Ho Pleiku (indv./m 3 ). Bien Ho Reservoirs 6/2000 10/2000 6/2000 10/2000 2.900 176.500 14.700 42.500 66.600 279.700 16.100 23.100 Thermocyclops hyalinus Thermocyclops hyalinus Dentodiaptomus javanus Thermocyclops hyalinus Nauplius copepoda Nauplius copepoda Thermocyclops hyalinus Nauplius copepoda Allodiaptomus sp. Ceriodaphnia laticauda Nauplius copepoda Dentodiaptomus javanus Zoobenthos: Chironomus sp., Limnodrilus hoffmeisteri. The Zoobenthos quantity is low from 20 170 indiv./m 2. 6.26 The analyzing results of the species composition structure and the quantity structure of aquatic flora and fauna in the water bodies of lake form show that Bien Ho (Pleiku) formatted 21

millions of years and Pleiku reservoir constructed in 1981, but they have not yet signed the poor about trophic side. 6.27 The relation of Zoogeography with other regions. With the Yunnam (China): The occurrence of species Dentodiaptomus javanus (Gromalicki). Gromalicki described this species in Java Island Indonesia (1915), Brehm found it in Cambodia (1951), Shen Chia jui and Tai Ai Yung Yannam province China (1964). In 1974, we collected species Dentodiaptomus javanus in Tay Nguyen and published the appearance in Tay Nguyen Vietnam (1979). We figured that this species occurs in the South East Asia regions with the elevations from 300 to 800 MSL. as the mountain area in Indonesia, Cambodia, Vietnam. The relation with the North Vietnam, the occurrence of Mongolodiaptomus formosanus Kiefer (Copepoda Diaptomidae) and Macrobrachium nipponensis de Haan (Decapoda Palaemonidae). With the North Central Vietnam, the occurrence of Vietodiaptomus hatinhensis Dang. The relation with Mekong Deltas (Mekong Delta of the South Vietnam and Mekong Delta of Cambodia), the occurrence of species of Copepoda Diaptomidae: Allodiaptomus mieni Dang, Tropodiaptomus vicinus Kiefer, Neodiaptomus botulifer Kiefer and species of Decapoda Palaemonidae: Macrobrachium lanchesteri. 6.28 The reservoir construction and the water resource exploitation in the Tay Nguyen water bodies serving for living and produce activities caused the changes of water survey by organic substance deposit. 6.29 The effect of herbicide and insecticide persistence used in wars to the water quality of water bodies need be studied more careful. e. Ecosystem of water bodies in the West Thua Thien Hue region. 6.30 It is a narrow land stretch located in the West Truong Son range. In this region, there are the upstream streams of the upstream of Xe Bang Hien River and some fishponds digging from the 80s to now. 6.31 Up to now, we know that only one the field trip organized by lectures of the Biology Falcuty the Hanoi University in 1980 the State Program, it presented above. The analyzing results, Nguyen Van Tuyen published 92 species algae in the report The freshwater algae in the areas effected by insecticide as Lang Co (An Cu Tay) and A Luoi (Nguyen Van Tuyen, CT 10 80). 6.32 Tran Anh Nguyet (The graduated subject the Hue University, 1983), showed the list of species of Crustacea found in A Luoi including Decapoda Macrura (5 species), Decapoda Brachyura (1 species), Copepoda 1 species. 22

6.33 In addition, in the book Vietnam Freshwater algae The classification of Chlorococcales described 4 species found in A Luoi: Pediatrum biradiatrum, Golenkinia paucispina, Oocystis borgei, Ankistrodesmus fusiformis (Duong Duc Tien Vo Thanh, 199). 6.34 Although, there is a little document in this area, but with occurrence of species Vietodiaptomus hatinhensis Dang (Copepoda Diaptomidae) and Caridina weberi sumatrensis De Man (Decapoda Atyidae) show that the West of North Truong Son range have related with the middle and downstream of Mekong River. 6.35 Conclusion, the record ecosystem studies in A Luoi The upstream of Xe Bang Hien is a few. 6.36 The construction of many fishponds The still water bodies have changed the running water characteristic of freshwater ecosystem in this region. g. Eecosystem of Dien Bien water bodies. 6.37 The Dien Bien waters belong to Mekong river basin including Nam Rom River, Huoi Phai reservoir, fishponds and rice fields. 6.38 Up to now, it is only one the field trip in this region organized by Dang Ngoc Thanh, Pham Van Mien. The sample analyzing results recorded: Rotatoria 10 species, Cladocera 7 species, Copepoda 8 species, Decapoda Macrura (2 species), Decapoda Brachyura (4 species). There is new taxa Macrobrachium dienbienphuense Dang et Nguyen Huy, 1972. Unfortunately, the Phytoplankton samples have not yet been classified. 6.39 The occurrence of Allodiaptomus calcarus Shen and Tai in Dien Bien showed that this ecosystem have the relation with Nui Dong areas in the North Vietnam. With the occurrence of two species of Decapoda Barcyura Somanniathelphusa brandti Bott, S. dugasti (Rathbun), species of Gastropoda Antimelania costula (Rafinesque), Sulcospira proteus (Bavay et Dautzenberg) and species of Decapoda Macrura Macrobrachium dienbienphuense Dang et Nguyen Huy (the morphology same as Macrobrachium pilimanus (De Man) distributed in Mekong Delta of Vietnam and Tay Nguyen) show that the relation closely with the freshwater ecosystem in the South of Indochina peninsula. The phenomenon is suitable with the conditions of hot and dried climate in Dien Bien. 6.40 In the field trip (1971), we recorded the occurrence of species of Mollusca Bivalvia Sinanodonta jourdyi (Morlet) in the Huoi Phai reservoir. This species has brought to Dien Bien together with fish species white carp, Chinese carp, grass carp. 23

h. The zoogeography location of these water bodies of Mekong Delta in Vietnam. 6.41 According to the zoogeography zonation system based on the distribution of freshwater invertebrate Starobogotor. J. I. (1970), the Indo - China region has three subregions: 0. The Amua Japan subregion. 0. The China sub-region. 0. The Indo Malai sub-region. 6.42 Thus, the aquatic fauna of the North Vietnam limited to Hai Van mountain pass belongs to the fauna province of the North Vietnam The China sub-region. 6.43 The aquatic fauna of the South Vietnam belongs to the Mekong fauna province including Lao, the East Thailand, Cambodia, and the South Vietnam The Indo-Malai subregion. 6.44 Based on the freshwater invertebrate structure in the North Vietnam, Dang Ngoc Thanh (1980) established a new sub-region for the Indo - China: the Vietnam South China sub-region including the South China province and the North Vietnam. 6.45 Thus, the flora and fauna in the border areas Dien Bien and A Luoi belong to the North Vietnam, the freshwater fauna in Tay Nguyen and Mekong Delta of Vietnam belong to the Mekong fauna province. According to Dang Ngoc Thanh (1980), it can separate the Mekong province to three areas: The area of Lao PDR the West Truong Son range with the endemic species composition of the elevation about 500m MSL. (The middle Mekong river). The area of Southeast Truong Son have the relation with the North Vietnam with the occurrence of fresh water organisms of Decapoda Brachyura and Bivalvia, The North Vietnam characteristic has also been seen in the fresh water fish composition in the Tay Nguyen (Chevey, 1937). 6.46 Pham Van Mien (1980) based on the distribution of Copepoda Diaptomidae merged areas such as the South Lao PDR, the Northeast Cambodia and the Tay Nguyen plateau into the separated region with the Mekong River Deltas (Cambodia and The South Vietnam). 6.47 The species composition in the Mekong river basin need be corrected to divide the zoogeography zonation and the landscape regionization served for the zonation of the economic development and the sensible exploitation of natural resources in the Mekong river basin. 24

CHAPTER 7. REVIEW AND ASSESSMENT OF THE MRB FRESHWATER ECOSYSTEMS IN VIETNAM 7.01 In fact, in 1863, Crosse and Fisher had monitored the inland water bodies ecosystems of Mekong River Basin in Vietnam territory, with the program of freshwater snail and mussel (Gastropoda and Bivalvia of freshwater) studies. They published 45 species of freshwater Gastropoda and Bivalvia in the South Vietnam and Cambodia. Continuously, Mabili and Le Mesle (1860), Morlet (1875), Rochebrune (1881, 1882), published 168 species of freshwater Gastropoda and Bivalvia in the South Vietnam and Cambodia. 7.02 In 1891, Fisher published 323 species of Gastropoda and Bivalvia of freshwater and brackish water in Thailand, Lao, Cambodia and Vietnam. In which, There are 148 species in Vietnam. 7.03 The most important and all-sided field trip in Indochina about these areas of society, geography, geology, biology, which carried out by Pavie group from 1879 to 1895. All samples were brought to France for classification. They published the results in 1904 (Mission Pavie T.III-1904). 7.04 In later periods, Roll (1904), Dautzenberg and Fischer (1905, 1908), Demange (1912), Haas (1912, 1924-1925, 1920), Prashad (1928) added some more new species for science. 7.05 About Decapoda, in 1898, De Man published the analyzing results of freshwater Decapoda samples in Indochina and Myanmar, Malaixia. These samples collected by Pavie group (De Man 1898, 1904 Mission Pavie III). 7.06 25 species found in these areas, there are 3 species in Vietnam: Parathelphusa sinensis, P. cochinchinensis, P. longipes. In which, only Parathelphusa sinensis have seen in the mountain areas of North Vietnam, and then Rathbun (1905) considered that it was a missed classification. According to Rathbun, it is new taxa. Parathelphusa geimaini. Rathbun (1902-1906) had studied all Decapoda - Brachyura samples in whole the world keeping in the Paris Natural History Museum. In which, the species composition of freshwater Decapoda Brachyura in Vietnam were 15 species with 12 species in the South Vietnam, the North Vietnam - 4 species. And then, Balss (1914) supported 2 species and Kemp (1923) added more 5 species in the South Vietnam. 7.07 Dang Ngoc Thanh (1967, 1975), Bott (1970) supported and revised about the taxonomy side of freshwater Decapoda Brachyura in Vietnam. 7.08 The Decapoda Macrura, in the Mission Pavie documents, De Man published only 3 species of Decapoda Brachyura in Vietnam and Thailand, and in 1914, Sollaud added 2 species Coutierella tonkinensis, Leander mani. Leander mani have only occurred in the North Vietnam. Bouvier (1904, 1920, and 1925) supported more 3 species Caridina weberi 25