A decadal observation on taxonomic composition of benthic macro-invertebrates with respect to water quality of River Yamuna.

摘要

The River Yamuna is divided into five distinct segments due to characteristic ecological segments. Present study reveals the status of water quality of River Yamuna almost ten years ago. In Himalayan segment water quality represented biologically clean water quality Class 'A' supported by Ephemeroptera > Plecoptera > Trichoptera. Water Temperature ranging between 6.5-21.50C, pH 7.35-7.95, Conductivity 83-247.5 micromhos/cm, DO 8.9-9.24 mg/l, BOD 1-1.2 mg/l, and COD 2-4 mg/l. There was significant increase in Total Coliform (27540-47151 Nos./100 ml) and Faecal Coliform (429-931 Nos./100 ml) during 2004-2005. In Upper segment, the biological water quality gradually deteriorated in this segment from Class 'A' at Lakhwar Dam D/s to Class 'C' at Wazirabad supporting benthic invertebrates belonging to Coleoptera > Plecoptera > = Hemiptera > = Diptera > = Crustacea > = Mollusca. Delhi segment of River Yamuna at U/s Okhla Barrage biological water quality of Heavy pollution Class 'D' with dominance of Mollusca > Hemiptera > = Diptera > = Hirudinea > Coleoptera. The DO levels were significantly reduced to 0.55 mg/l in Delhi segment. Thus depletion in DO levels of River Yamuna is deleterious to aquatic life and required improvement in water quality. In Eutrophicated segment dominance of Coleoptera > = Mollusca > Odonata > = Hemiptera supported Class 'C' (Moderate pollution) in water quality. There was an abrupt increase in pH 7.55-8.25 and Conductivity (793.5-1171.5 micromhos/cm) in water. There was no change in biological water quality (Class 'C') of Diluted segment of River Yamuna supporting dominance of Mollusca > Hemiptera > Coleoptera. In this segment, the level of Total Coliform (74122916 Nos./100 ml) and Faecal Coliform levels (1442886 Nos./100 ml) were mainly contributed through Delhi segment of River Yamuna.