Impact of anthropogenic wastes on diversity of live food spectrum of river Gomti at Daliganj in Lucknow (India)

Abstract

Daliganj site of river Gomti receives sewage and industrial wastes from the thickly populated locality of Lucknow. The water quality was poor with higher nitrate (22.70 mg l-1) and phosphate (2.40 mg l-1). Chlorophyll 'a', 'b' and 'c' were high with Chlorophyceae being the dominant phytoplankton group comprised chiefly Closteridium, Cladophora, Gonatozygon and Cosmarium while zooplankton contents were low. Cladocerans (Moinodaphnia, Ceriodaphnia) and copepodes (Cyclops) dominated the zooplankton fauna. The benthic fauna which serves food for most of the bottom feeding fishes was exceptionally rich. High population density of benthos was due to oligochaetes (Lumbriculus, Limnodrilus, Branchiura, Chaetogaster, Nais and Tubifex) and Chironomus larvae. Branchiura, Tubifex, Chironomus and Diptera (Culicoid larvae), the organic pollution indicators, dominated the fauna. Shannon-Wiener Diversity Index (H) of benthic organisms was less than 1 for oligochaetes, Diptera, Coleoptra and Gastropoda indicating stressed environment. Though the benthic density was high, it may not contribute to the food chain. Relatively low abundance of plankton population and biomass in spite of high nutrient budget of the system appears to be due to the high infestation of water quality by pollutants suggesting extreme state of deterioration of water quality with non-conducive ecological regime for fisheries development.