
Zooplanktons are good indicators for changes of water quality, because they are strongly affected by environmental conditions and respond quickly for the changes in environmental quality. The present study was carried out to examine the diversity and density of zooplankton in Ukkadam lake, Coimbatore, Tamil Nadu, India, for the period of one year from May 2003 to April 2004. During the present study period, a total of 36 genera of zooplankton composed of 8 genera of protozoa, 6 genera of Rotifera, in which 7 genera belonged to Cladocera and 6 to Copepoda were recorded in all the three stations during the period of study. Rotifera were observed to be maximum during summer (March, April and May) and dominated other genera. Species Diversity Index calculated for zooplankton population varied from 1.74 to 3.63. Maximum numbers of zooplankton were recorded in the months of March and October. Dominance of Rotifers is indicated the eutrophic status of lake. The present study result was clearly indicating intensified eutrophication of lake.