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Biomonitoring of the Lower Mekong River and Selected TributariesMRC Technical Paper No  

Biomonitoring of the Lower Mekong River and Selected TributariesMRC Technical Paper No. 13

The ecological health of the Mekong River and its tributaries is vitally important to lives and livelihoods of the more than 60 million people who live in the Lower Mekong Basin (LMB). The Mekong River Commission (MRC) is developing systems that will help to manage the ecological health of the river. Biological assessment (biomonitoring) is one of the tools that will support this management. . The 2004 biomonitoring survey was part of a five-year MRC project aimed to develop a biomonitoring method designed specifically for the environmental conditions of the Mekong River and its tributaries.Accordingly, the principal objective of this survey was to test methodologies rather than to provide definitive information about the ecological health of the river and its tributaries. . The survey sampled 20 sites along the length of the Mekong system from northern Thailand, through Lao PDR and Cambodia, to southern Viet Nam. Data were collected on four groups of organisms, benthic diatoms, zooplankton, littoral macroinvertebrates and benthic macroinvertebrates, which are believed to be best suited for biomonitoring purposes. Physical and chemical data were also collected to assist in interpretation of the biological data. Analysis of these data aimed to: . 1. Examine the diversity, abundance and composition of the aquatic communities at each site; 2. Identify those physical and chemical variables that most strongly associate with spatial variations in the biological communities; 3. Compare the within-site and among-site variability of community composition. . The analyses found that all four groups of organisms are diverse and abundant in the Mekong River system, with considerable variation in abundance and composition from site to site. Spatial variation among sites was related to environmental variables such as temperature, electrical conductivity (an indicator of salinity), pH, and dissolved oxygen concentration. Statistical analyses also showed that in the case of each group, replicate samples from the same site were almost always more similar to one another than to samples from other sites. This shows that the sampling methods are well able to assess biological differences among sites. . The results of the 2004 survey demonstrate that biomonitoring is potentially a valuable tool with which to assess the ecological health of the Lower Mekong river-system. Future surveys will build on the 2004 survey by including additional sites and providing more comprehensive, and representative, coverage of the Lower Mekong Basin. In future the project will also develop and test biological indices that are able to distinguish deleterious human impacts from the effects of natural variation in environmental variables.

Uploaded on: Jul 2008
File size: 3.4 MB - Language: English
Keyword(s): Biodiversity/Protected Areas , Natural Resources Management
Category: Environment