Macrobenthos are mainly composed of polychaetes, crustaceans, molluscs, and many other taxonomic groups. The structure and diversity of this community are influenced by riverbed type, bio-physic-cemical characteristics, and depth. Its difficult to answer correlated to for the scoping "not pollutants" because any activities will result in pollutant accumulation/contribution. Once human footprints (fishing, physical movements, livelihood activities, etc) with differing intensities intact with environment indirectly or directly will affect the quality of the stream and furthermore will impact on the macrobenthic existence (diversity) in that stream. It is because its diversity depends on bio-physic-chemical of the water, substrate requirements, and food availability. For example, the more human discharge waste into the stream result in high BOD and give impact on the structure of the macrobenthic fauna community in the stream. Fishing activities (poisoning or electrical rod) could give impact on the composition and diversity of macrobenthic species. As an example, fish poisoning will cause river/riverbed/sediment contamination that will cut energy transfer to macrobenthic level (because the contaminant/toxic will poison the lower trophic level) and affect fishery that lead to human-health problem. More complex, if there is a water flow discharge from farming areas. the fertilizers or pesticide will be washed out to the river and result in river/riverbed/sediment contamination. So each human activity will have consequence (s) to the stream.

Thank you so much for the valuable information dear Sulistiyowati Hari, here i noticed most of the activities are religious and rituals, whereas in some places they do domestic activities like bath, wash; i just need to know the impacts of huge gathering of some ceremonies which are held along the river.

Ok I understand that, so how they do the ritual becoming important. do the people step their feet inside the river or they just prepare the ritual along the riverbank. The physical activities (walking along the river) will impact on flow and riverbed. Do they left over debris/materials (biodegradable or degradable, toxic -nontoxic)? High accumulation of solid waste will block light penetration, sedimentation, other. How frequent is the ritual done? the more frequency people do ethno practices the more impact on the river ecosystem. (the impact is similar to my previous explanation, but different in degree of pollutant) In my country they do ritual once a year by using very small boat (for putting biodegradable material: vegetable, flower, fruits). they do ritual outside the river, lake, ocean ecosystems then they push the boat on the river (let it go through the stream); sometime people taking a bath (put some flower commonly roses and jasmine) in the river. that so far I understand about the ethnic practices.

Thank you so much dear Sulistiyowati Hari, here things are very different, most of the rituals are within the river flow, physical activities are more, left over all materials, biodegradable and non degradable, more often this take place once in a month, they preparing food along the bank areas, and left the remains there itself, starting of monsoon period all debris along the banks were washed into the system, we can see those things along the bank vegetation after the high flow, which are sticky on those plants/trees

So actually, you could investigate the quality of river (water quality, biodiversity, etc) through time (chronosequence) driven by that ethno-practices. you could make a simulation or model ; comparison based on season, based on type of ritual/ceremonial actions; impact analysis; or other purposes (its challenging),. The outputs are good information to do further analysis on socio-cultural valuation, to make policy/decision.

thank you for the sharing, its interesting. Good luck

The problem highlighted by Dr.Kani and the discussions made with Dr.Hari is interesting and such incidence is common along most of the streams & rivers in India. A perennial stream is more affected by such kind of anthropogenic activities and it is obvious that macrobenthic fauna will be affected severely. This can be studied by comparing the diversity of benthos in both impact and non-impact zones of the same stream, as also with neighboring similar kind of stream.

Further consideration besides the introduction of waste in to the river is the physical disturbance and impacts that could be caused by trampling. There is potential to increase physical bank damage through erosion, which can contribute to increased sedimentation in the river and adversely affect invertebrates through smothering, especially considering the size of some ritual gatherings. Also, depending on the scale of people entering the river, direct disturbance effects could also be a significant factor; disturbing the substratum can dislodge invertebrates and mobilise sediments for downstream transport. The dislodgement of invertebrates would reduce invertebrate population densities and if the ritual is regular (monthly) and of a significant scale (dependant on river size and the number of people) there is potential that the locally impacted invertebrate populations may not recover fully until the practice ceases or reduces in regularity or scale. You may therefore encounter higher invertebrate population densities above and below the disturbed area. Not forgetting that there could also be increased impact of sedimentation further downstream too.

Diversity of macrobenthic organism s will decrease with increase of human activities except the population of opportunistic species