Sharma, J. G. and Chakrabarti, R. 2000. Seasonal occurrence of freshwater medusa Limnocnida indica in a lake of river Yamuna, India. Aquatic Ecology 34: 205-207.

A freshwater medusa, Limnocnida indica Annandale, 1912 was observed in the month of April and May of two consecutive years 1994, 1995 in a lake having free connection with the river Yamuna in Delhi. Medusae in the lake were abundant in those areas where the vegetation of Hydrilla sp. was moderately dense, whereas it was absent in areas with Potamogeton sp. The composition of planktonic community in the lake was different before and during the occurrence of medusae and after their disappearance. Moina sp. and Keratella sp. were totally absent and Mesocyclops sp. and nauplii were reduced in number during the occurrence of medusae, which were either present or more in number before the occurrence of the latter. Dinophyceae was maximum in number during this period. These zooplankters reappeared after the disappearance of medusae. It is likely that ecological condition, which prevailed during April and May favour the seasonal occurrence of freshwater medusae.

Anand, C., Akolkar, P. and Chakrabarti, R. 2002. A comparative bio-assessment of water quality on east and west bank of river Yamuna in Delhi. In: Water and Wastewater Perspective of Developing Countries (eds. Devi, R. and Ahsan, N.). 433-441 pp.

An attempt had been made to assess the impact on water quality of diverse anthropogenic activities on east and west bank of river Yamuna in Delhi, from Palla to Okhla Barrage, both biologically as well as chemically. Bioassessment had been done using benthic macroinvertebrates as bioindicators of pollution. Biological water quality in terms of number and type of families at upstream and downstream of river Yamuna in Delhi for the few past years had been analysed with the present status. The study also determines the impact of 3 barrages - Wazirabad, Yamuna (ITO) and Okhla barrage and the impact of substratum type on biological life of the river. Biological life was observed to be more affected on east bank of the river than on west bank, probably due to heavy anthropogenic influence on east bank. Over the years, general numbers of families have increased but low scoring pollution resistant benthic families have replaced the high scoring sensitive benthic families. Favourable habitat at upstream of the barrage supports more biological life than downstream. Biomonitoring gives an overall health of the water body cost-effectively, which could not be done by chemical analysis alone.

Anand, C, Akolkar, P. and Chakrabarti, R. 2004. Benthic Macro-invertebrates of River Yamuna in Delhi stretch at various levels of Physico-chemical water quality parameters. Research Journal of Chemistry and Environment 8: 15-23

River Yamuna in NCT-Delhi, from its upstream at Palla till its downstream at Okhla reservoir was selected to determine benthic macro-invertebrate fauna composition at various levels of physico-chemical water quality parameters. Monthly sampling was conducted at six locations on river Yamuna in Delhi from January 2002 to December 2002. The river in Delhi city is subjected to various anthropogenic influences which result in water quality degradation and hence change in benthic fauna composition. The study determines the ranges of the selected physico-chemical parameters for the benthic families encountered. The physico-chemical characteristics of water quality, supporting benthic macro-invertebrates, were assessed by pH, conductivity, total dissolved solids, dissolved oxygen, chemical oxygen demand (COD) and biochemical oxygen demand (BOD). Annual % abundance of benthic macro-invertebrate taxa encountered was evaluated at all the locations. Benthic fauna composition alters with change in physico-chemical characteristics of water quality. Low levels of physico-chemical parameters supported benthic families viz Caenidae & Hydropsychidae. These benthic families were replaced by families belonging to Mollusca, Hemiptera, Coleoptera, Diptera and Oligochaetes with increase in levels of physico-chemical characteristics.