Tien River Estuary
Location:
 9°45'-10°20'N, 106°02'-106°48'E; 50-120 km south of Ho Chi Minh City, Ben Tre Province.
Area:
c.25,000 ha.
Altitude
 0-1.5m.
Biogeographical Province:
4.5.1.
Wetland type:
 02, 06, 07, 10, 11 & 19.
Description of site:
 The estuarine system of the Tien River, the northernmost of the two main distributaries of the Mekong River. The Tien River has six distributaries which enter the sea along the coast of Ben Tre Province, in the northeastern part of the delta. There are extensive intertidal mudflats and some 16,500 ha of mangrove forest at the river mouths, and cultivated plains with a complicated system of canals inland, in recent years, large areas of mangrove forest have been cleared for shrimp and fish ponds. Salinities range from 0.5-30.0 p.p.t.; the tidal amplitude varies from l.Sm at neap tides to 4.Om at spring tides.
Climatic conditions:
 Tropical monsoonal climate with a pronounced dry season from December to April and a rainy season during the southwest monsoon from May to November. The average annual rainfall is 1,495 mm (maximum 2,285 mm, minimum 955 mm), 85% of the precipitation occurring between May and November. The mean annual temperature is 26.0-27.9°C (mean maximum 32.7°C, mean minimum 23.1°C); the highest temperatures occur in April (34.7°C), and the lowest in January (20.8°C). The mean annual relative humidity is 79.4% (maximum 82.5% in August, minimum 74.1% in April); the mean annual evaporation is 1,159 mm.
Principal vegetation:

Mangrove forest dominated by species of Avicennia, Phoenix, Acanthus, Nypa fruticans and Hibiscus sp. The mangrove forests are now much degraded as a result of over-exploitation for firewood and clearance for aquaculture. The phytoplankton includes 278 species of Bacillariophyta, Pyrrophyta and Cyanophyta. The dominant genera are:

Melosira (9 species) Thalassiosira (5)
Cyclotella (6) Cossinodiscus (20)
Rhizosolenia (20) Bacteriastrum (8)
Chaetoceros (38) Bidduiphia (14)
Thajassionema (4) Achnanthes (4)
Navicula (13) Pleurosigma (4)
Nitzchia (18) Peridinium (23)
Ceratium (28)  

Densities of 114,000 to 3,100,000 individuals per cubic metre have been recorded.

Land tenure:
 Under cooperative ownership.
Conservation measures taken:
 None.
Conservation measures proposed:
  
Land use:
 Fishing, aquaculture and outdoor recreation. Aquaculture is very intensive; in 1980 there were 1,800 ha of shrimp and fish ponds, and this area had been increased to 3,550 ha by the following year. The adjacent plains are under cultivation for rice, sugar cane and coconuts.
Possible changes in land use:
  
Disturbances and threats: The major threat is the clearance of mangrove forest for aquaculture ponds. The loss of mangrove forest is having an adverse effect not only on waterfowl populations but also on the natural estuarine and inshore fisheries.
Economic and social values: The mangrove forests provide breeding and nursery grounds for many commercially important species of fishes and crustaceans. The estuary supports a major fishery, yielding about 5,500 metric tonnes of fishes and 1,300 metric tonnes of shrimps per year. The region is also a popular recreation area for the people of Ben Tre Province.
Fauna:

Thirty-six species have been recorded in the zooplankton, including Rotatoria (1), Cladocera (2), Copepoda (26), Chaetognatha (2), Tunicata (2), Pteropoda (I), Decapoda larvae (1) and Stomapoda larvae (1). The zoobenthos includes 13 families of arthropods and eight families of molluscs. Many species of brackish water shrimp, such as Penaeus indicus, P. monodon, P. merguiensis, Metapenaeopsis barbata and Metapenaeus monoceros, occur along with several species of crabs of the genus Scylla.

The fish fauna includes Lamniformes (1), Rujiiformes (3), Torpediniformes (1), Clupeiformes (15), Scopheliformes (2), Anguilliformes (4), Cypriniformes (2), Betoniformes (1), Gadiformes (1), Syngnathiformes (1), Mugilliformes (3), Polynemiformes (3), Pereiformes (54), Pleuronectiformes (7) and Tetrodontiformes (4). Most of the fishes are marine and brackish water species; freshwater species which sometimes occur include Protus anguileauctatus, Leioeassis siamensis, Siluriliethys phaiosoma, Kryptopterus kryptopterus, Clarias macrocephalus, C. batrachus and Trichogaster trichopterus.

The intertidal mudflats and mangrove swamps are known to be very important for a wide variety of waterfowl, particularly migratory shorebirds, but no details are available.
Special floral values: No information.
Research and facilities: Some research has been carried out on the planktonic fauna and flora and the fishery resources.
Criteria for inclusion: 1b, 1e, 2c, 3b.
References: Vu Trung Tang et al. (1981).
Source:
 Le Dien Due.