DYNAMICS AND DIVERSITY OF MACROZOOBENTHOS IN THE GLACIER FED STREAM BALKHILA AT SIRON IN CHAMOLI GARHWAL

The present study was carried out to investigate the dynamics and diversity of macrozoobenthos at Siron during November, 2018 to October, 2019. The various physico-chemical parameters were analysed on monthly basis throughout the year. The river is represented by seven major benthic orders namely Ephemeroptera (Baetis, Cinygmula, Caenis and Heptagenia), Trichoptera (Glossosoma, Rhyachophila, Agapetus, Hydropsyche, Chimarra and Stenopsyche), Diptera (Tabanus, Atherix, Chironomus), Coleoptera (Psephenus), Neuroptera (Corydalus), Odonata (Euphaea) and Plecoptera (Perla). The maximum density was 355 units. m-2 in the month of March, which was dominated by Ephemeroptera and Trichoptera followed in decreasing order by Coleoptera, Diptera, Plecoptera, Odonata and Neuroptera. This trend of dominance was supported by cluster analysis dendrograms. Benthic population showed negative correlations with current velocity, turbidity and water temperature and positive with pH, DO, Alkalinity and Total hardness. Highest similarity in taxa was obtained in winter and summer months and least in monsoon. Shannon-Wiener diversity index was maximum (2.17) in October and minimum (1.28) in August which showed conducive environmental conditions during autumn. The Canonical correspondence analysis (CCA) represented that four benthic organisms [Cinygmula (Ephemeroptera), Hydropsyche and Stenopsyche (Trichptera) and Psephenus (Coleoptera)] were dominant and available round the year. The maximum density and diversity was found in winter season and minimum in monsoon. Coefficient of Similarity was traced between the total benthic population round the year.