Yes what you said was correct, most of the international studies mainly concentrated on wadeable rivers because of the organisms richness, light penetration and the availability of substratum as pebbles. Unfortunately in large river or in higher depth the sampling will be a challenging one.

River side monitoring may help in this regard instead of assessing in the middle of the flow.

Thank you for your efforts; and my prayers to succeed in this study.

did you have a look at www.fliessgewaesserbewertung.de ?

here you find the description of PERLODES, the german assessment system for macroinvertebrates. At the pdf: http://www.fliessgewaesserbewertung.de/downloads/abschlussbericht_20060331_anhang_IX.pdf

you will find the instructions-document, including sampling methodologies for large rivers as practised in Germany for Assessment according to EG-Waterframework-Directive. Perhaps that helps too.

regards, Andre

Many analyses from wadeable rivers/brooks are based on some form of netting and using the flow to catch invertebrates.

For large rivers with a low water speed, you may want to look at methods used in standing waters and lakes including grabs, corers for taking sediment samples (for benthic organisms depending on the depth where they occur in the sediment) and/or devices that are colonised by invertebrates. There are a good many number of publications available on RG: e.g. A comparative study of seven grabs used for sampling benthic macroinvertebrates in rivers by ELLIOTT and DRAKE

Article On the reliability of Ponar grab samples for the quantitativ...

I wonder if this situation can be equated with the Himalayan rivers and their major glacierfed tributaries that are difficult to sample across the width where dredge can not be used because of large boulders and cobble on the bottom and secondly because remaining static at one place is a challenge in torrential rivers due to high gradient. Any experiences or methods that suit such situation.

Can i suggest treating these rivers as marine environments and use marine sampling techniques on a smaller scale. Ocean expeditions regularly sample for micro and macroinvertebrates using there techniques or adapting these techniques may provide some useful results

Take a look at this report by the US EPA,

http://water.epa.gov/type/rsl/monitoring/riverssurvey/upload/non-wadeable_full_doc.pdf

Use a vessel and trawl a large and heavy dredge with relativelly small mesh; it should work for mussels and large epibenthic animals; or mega box corers for small infauna

The report by the team which designed a bio assessment program for the Mekong River would be useful too.

Reference is MRC (2010) Biomonitoring Methods for the Lower Mekong Basin. Mekong River Commission, Vientiane. 65 pp.

from the publications section of the MRC website - www.mrcmekong.org

Air-lift sampler – operates using compressed air and can access benthic habitats from 2-5 m deep

Coir samplers – provides a standard structure typical of root mat habitats; can be deployed over a range of depths.

Dear Angelo,

Thanks a lot - a nice publication with a lot of interesting data. Maybe, we can use a wider dataset to try to extend the study. We also used different sampling methods. If you are interested, after the hollidays and field work period (sometime in October, let say), we can continue discussion and try to compare the data from different areas.

Regards,

Momir