Key Words: Tidal flat, Tra Vinh, Coastal area, Depositional environment, Hard clam, Clam farming ground.
J. Bio. Env. Sci. 13(2), 58-67, August 2018.
Tra Vinh is a coastal province in the Mekong River Delta, Vietnam with about 65 km coastline located between the Co Chien and Bassac rivers and bordered to the south east by the East sea. In Tra Vinh coast, tidal flats occupy the widespread area along the coastline to -5 m water depth, consisting of mud and sand flats. On the mud flats, especially around the river mouths, extensive mangroves distribute and provide abundant food for aquatic species. These natural conditions are very favorable for the development of marine brackish water aquaculture especially hard clams Meretrix lyrata. Clam farming is considered a potential aquaculture and has contributed considerably to socio-economic development of the locality. However, the cultured area only accounts for about 20% of the total tidal flat area, the development is not commensurate with the potential and available advantages. In order to exploit effectively and reasonably potential of tidal flat and develop sustainably clam farming in Tra Vinh coastal area, it is necessary to study the natural and environmental characteristics for planning suitable culture areas. Combining methods of topography survey, boring cores and analysis of grain size, environmental factors in laboratory, main natural and eco-environmental factors affecting clam culture process are clarified. Morph-sedimentary of tidal flats, meteorological, marine hydrological and environmental characteristics of Tra Vinh coastal area are favorable for hard clam culture. Clam grounds in coastal tidal flat and river mouth bar are characterized by75- 90% fine sand, stable and flat topography slightly sloping towards the sea, mean 4 – 8 h/day exposure time in 2.5- 3m water depth corresponding to topography -1.5 to -2.6 m. Depending on geographical location of tidal flats, adverse factors would affect heavily to the clam grounds also are defined.
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