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.