Mekong River Commission Cambodia Lao PDR Thailand Viet Nam Office of the Secretariat in Phnom Phenh (OSP) Office of the Secretariat in Vientiane (OSV) 567 National Road, Office of the Chief Execuive Officer #2, Chak Angre Krom, 184 Fa Ngoum Road P.O.Box 623, Phnom Penh, Cambodia P.O. Box 6101, Vientiane, Lao PDR Tel : (855-23) 425 353 Tel : (856-21) 263 263 Fax : (855-23) 425 363 Fax : (856-21) 263 264 Report on the 2011 Biomonitoring Survey of the Lower Mekong River and selected tributaries MRC Technical Paper No.43 | April 2014 ISSN: 1683-1489 MRC Technical Paper No.43 April 2014 Report on the 2011 Biomonitoring Survey of the Lower Mekong River and selected tributaries Report prepared by Mekong River Commision Environment Programme ISSN: 1683-1489 MRC Technical Paper No.43 April 2014 Report on the 2011 Biomonitoring Survey of the Lower Mekong River and selected tributaries Report prepared by Mekong River Commision Environment Programme Published in Vientiane, Lao PDR in April 2014 by the Mekong River Commission Suggested citation: CHHENG Phen, DO Thi Bich Loc, Tatporn KUNPRADID, Henrik LARSEN, NGUYEN Van Duyen, Niane SIVONGXAY and Chavalit VIDTHAYANON (2014). Report on the 2011 Biomonitoring Survey of the Lower Mekong River and selected tributaries, MRC Technical Paper No. 43. Mekong River Commission, Vientiane, 78 pp. The opinions and interpretation expressed within are those of the authors and do not necessarily reflect the views of the Mekong River Commission. Editors: Robyn Taylor, Robert Brown Photographers: © Mekong River Commission © Mekong River Commission Office of the Secretariat in Phnom Penh (OSP) 576 National Road, #2, Chak Angre Krom, P.O. Box 623, Phnom Penh, Cambodia Tel. (855-23) 425 353. Fax (855-23) 425 363 Email: [email protected] Office of the Secretariat in Vientiane (OSV) Office of the Chief Executive Officer 184 Fa Ngoum Road, P.O. Box 6101, Vientiane, Lao PDR Tel (856-21) 263 263. Fax (856-21) 263 264 Website: www.mrcmekong.org Table Of Contents List OF FIGURES IV List OF TABLES V Acknowledgements vi ACRONYMS VII Glossary viii Summary xiii 1. Introduction 1 2. Materials & METHODS 5 Sampling sites 6 Data collection and identification 16 Calculation of biometric indicators 21 Using biological indicators to evaluate sites 21 Designation of reference sites 22 3. RESULTS & DISCUSSIONS 27 Physical environmental variables 28 Benthic diatoms 31 Zooplankton 35 Littoral macroinvertebrates 38 Benthic macroinvertebrates 42 Evaluation of sites 46 4. Conclusions 51 5. REFERENCES 55 APPENDIX 1. List OF participants ON THE SAMPLING FIELD TRIP IN 2011 57 APPENDIX 2. Description OF 41 SAMPLED SITES IN EHM 2011 59 Report on the 2011 Biomonitoring Survey of the Lower Mekong River and selected tributaries iii List of Figures Figure 1.1 Timeline for biomonitoring in the Mekong River and its tributaries 2003 to 2013 _________________________________________3 Figure 2.1 Reference sites (stars) selected and agreed in 2004–2008 biomonitoring activities __________________________________23 Figure 2.2 Sampling sites in the Lower Mekong Basin surveyed in 2011 and their ratings __25 Figure 3.1 Ecological health rating in the Lower Mekong Basin (2011 survey) ____________53 Figure 3.2 Comparison of number of sites per ecological class in 2008 and 2011 _________54 iv Report on the 2011 Biomonitoring Survey of the Lower Mekong River and selected tributaries List of Tables Table 1.1. Lao PDR sites sampled in 2011 and earlier biomonitoring surveys _____________6 Table 1.2. Thailand sites sampled in 2011 and earlier biomonitoring surveys _____________8 Table 1.3. Cambodia sites sampled in 2011 and earlier biomonitoring surveys __________11 Table 1.4. Viet Nam sites sampled in 2011 and earlier biomonitoring surveys ___________14 Table 2.1. Guideline for biological indicators of ecosystem health based on 2004–2007 baseline studies ___________________________________________24 Table 3.1. Physical environmental variables at the 41 sites sampled in 2011 ____________29 Table 3.2. The values of average abundance, richness and ATSPT for benthic diatoms (2005–2011) ________________________________________________________32 Table 3.3. The values of average abundance, richness and ATSPT for zooplankton (2005–2011) __________________________________________37 Table 3.4. The values of average abundance, richness and ATSPT for littoral macroinvertebrates (2005–2011) ______________________________39 Table 3.5. The values of average abundance, richness and ATSPT for benthic macroinvertebrates (2005–2011) _____________________________43 Table 3.6. Assessment of all sites in 2011 following the suggested guidelines ____________45 Table 3.7. Site assessment (2005–2011) __________________________________________47 Report on the 2011 Biomonitoring Survey of the Lower Mekong River and selected tributaries v Acknowledgements The authors would like to express their The authors also express their appreciation appreciation for the support given to the to Mr. Hans Guttman, Dr. Truong Hong Tien, study by the representatives from the Dr. Tran Duc Cuong and Mr. Xiong Tsech- National Mekong Committees of Cambodia, licha for their comments, reviewing and Lao PDR, Thailand, and Viet Nam, partic- suggestions in drafting the report. ularly for supporting logistics both in the field and in the workshop platforms for the 2011 monitoring programme. vi Report on the 2011 Biomonitoring Survey of the Lower Mekong River and selected tributaries Acronyms ATSPT Average Tolerance Score Per Taxon BDP Basin Development Programme of the MRCS EHM Environmental Health Monitoring LMB Lower Mekong Basin MRC Mekong River Commission MRCS Mekong River Commission Secretariat NMC National Mekong Committee SDS Site Disturbance Score Report on the 2011 Biomonitoring Survey of the Lower Mekong River and selected tributaries vii Glossary Abundance A measurement of the number of individual plants or animals belonging to a particular biological indicator group counted in a sample. Low abundance is sometimes a sign that the ecosystem has been harmed. Average richness The average number of taxa (types) of plants or animals belonging to a particular biological indicator group (e.g. diatoms, zooplankton) counted in the samples from a site. Average Tolerance Each taxon of a biological indicator group is assigned a score that relates to its Score per Taxon tolerance to pollution. ATSPT is a measure of the average tolerance score of the (ATSPT) taxa recorded in a sample. A high ATSPT may indicate harm to the ecosystem, as only tolerant taxa survive under these disturbed conditions. Benthic In this report, this term refers to animals that live in the deeper parts of the macroinvertebrates riverbed and its sediments, well away from the shoreline. Because many of these species are immobile, benthic macroinvertebrates respond to local conditions and, because some species are long living, they may be indicative of environmental conditions that are long standing. Biological indicator Groups of animals or plants that can be used to indicate changes to aquatic groups environments. Members of the group may or may not be related in an evolutionary sense. So, while diatoms are a taxon that is related through evolution, macroinvertebrates are a disparate group of unrelated taxa that share the characteristic of not having a vertebral column, or backbone. Different biological indicator groups are suitable for different environments. Diatoms, zooplankton, littoral and benthic macroinvertebrates and fish are the biological indicator groups most commonly used in aquatic freshwater environments. In addition, although not strictly a biological group, planktonic primary productivity can also be used as an indicator. However, for a number of logistical reasons, fish and planktonic primary production are not suitable for rapid ecosystem health assessment in the Mekong. Diatoms Single-celled microscopic algae (plants) with cell walls made of silica. They drift in river water (benthic/planktonic) or live on substrata such as submerged rocks and aquatic plants (benthic/benthonic). They are important primary producers in aquatic food webs and are consumed by many invertebrates and fish. Diatoms are a diverse group and respond in many ways to physical and chemical changes in the riverine environment. Diatom communities respond rapidly to environmental changes because of their short generation times. viii Report on the 2011 Biomonitoring Survey of the Lower Mekong River and selected tributaries Environmental Chemical and physical parameters that were recorded at each sampling site variables at the same time as samples for biological indicator groups were collected. The parameters include altitude, water transparency and turbidity, water temperature, concentration of dissolved oxygen (DO), electrical conductivity (EC), activity of hydrogen ions (pH), and concentrations of chlorophyll-a, as well as the physical dimensions of the river at the site. Littoral In this report, the use of this term refers to animals that live on, or close to, macroinvertebrates the shoreline of rivers and lakes. This group of animals is most widely used in biomonitoring exercises worldwide. They are often abundant and diverse, and are found in a variety of environmental conditions. For these reasons littoral macroinvertebrates are good biological indicators of environmental changes. Littoral organisms Organisms that live near the shores of rivers, lakes, and the sea. Macroinvertebrates An informal name applied to animals that do not have a vertebral