Dear Dhiya,

It may be that the high/fast flows you describe may not provide suitable habitat for the aquatic species you wish to investigate, or if so you might be able to first target suitable habitat to sample by conducting a physical habitat assessment (PHA). Obviously, concreted surfaces provide other complications for habitat for aquatic biota (i.e. high velocities, laminar flow problems, etc). Here is a citation for a paper recently published for such assessments in urban rivers/streams:

Hooper, L., and J.A. Hubbart. 2016. A Rapid Physical Habitat Assessment of Wadeable Streams for Mixed-Land-Use Watersheds. Hydrology, 3(4), 37; DOI: 10.3390/hydrology3040037

This publication along with included citations may help provide you a way forward as it covers PHA and also by virtue of citations included biomonitoring methods (particularly macroinvertebrates). Best wishes and best of luck! Jason Hubbart

Dr. Hubbart's ideas are great to consider, apply.  Since habitat is so limited, you might try installing some home or lab made, portable habitat boxes, with substrates of suitability as rocks, stems, mossy wood pieces, etc.  Select some rocks where the macrointebrates can hide or attach without being blasted off. I dont have any publications on making artificial habitats for sampling.  Something like a crab pot may work to hold subtrates.  Use anchor or tie to bank with strong rope or cable.  You may have to be inventive if you expect to install it in wide deep, fast channel by using a strong piece of rebar or pipe secured to bank and carefully pushed out in the flow and secured.  Otherwise it is apt to be rolled or moved on rope with high current to along bank.  Perhaps you would need ropes on both banks.  Come back in a week or two, or monthly and see if anything present.  Best to install, check in periods of low flow. If you get nothing or afraid organisms will leave when disturbed,  you might try adding some mesh or even filter fabric, or securing to a bottom pan so it can be dragged out with less interruption or escape.  I cannot guarantee you will get much in concrete habitat of urban waters, but even urban streams may get some sediments or bedload from headwaters.

Hi Dr Hubbart and Sir William, so great to receive your feedback! Thank you.

Yes, actually we did an experiment by putting old tyres anchored to river bank/stones, somehow it flushed away and missing within two weeks.

I will check on the paper mentioned on PHA and also alternative habitat creation for invertebrates for biomonitoring.

Thank you!

There are standardised colonisation chambers for sampling macroinvertebrates in sites with poor physical habitat. In the UK there are cylindrical chambers made of plastic which are about 20cm in height/diameter. I haven't used them for many years but I presume they are still available. I think other standard chambers are used elsewhere around the world. I think you would be able to screw/bolt something like that directly to a concrete channel.

Another possibility is air-lift sampling, which in the UK is used in deep rivers but generally with soft sediments. This method sucks up invertebrates remotely, so you will actually be sampling what is there in the habitat provided rather than sampling what would be there if the habitat were better (which is what you sample using a colonisation chamber).

What you do really depends on what questions you are trying to answer. Clearly you are dealing with a hostile artificial environment which has limited physical habitat provision, so if you are trying to highlight this then you need a method that will sample the invertebrates that manage to cope with that habitat - modified airlift sampling might work. If you're trying to highlight the recolonisation potential following some form of physical habitat restoration or improvement, then recolonisation chambers would be better. These better reflect the potential for invertebrate drift from upstream areas (hopefully of better physical habitat quality, and also of good watger quality) to provide colonists for restored habitat through the urban section. Using both types of method would provide information about both the quality of existing habitat conditions and the benefits of habitat improvement.

Hi Sir Chris, thank you for the suggestions. I will study the methods suggested. Thank you Sir.