Abstract In the present investigation the water qualityvariables and zooplankton occurrence in freshwaterhabitats (ponds/lake) in and around urban and suburbanenvironments of Chennai city were analysed fromNovember 1999 to May 2001. The surface watertemperature showed a minimum of 23oC which wasrecorded during the post monsoon season. The pH wasfound to be alkaline with a narrow range (8.76) atMadhavaram pond during monsoon season. The highervalue of hardness (608mg/l) and lowest value (60mg/l)were recorded during pre monsoon season andmonsoon season at Chetpet and Madhavaram pondsrespectively. The average alkalinity valueswerehighatChenglepetlake (1804 mg/l) during the Summerseason, it declined(24 mg/l) in the Madhavaram pondduring premonsoon season.The maximum nitrateconcentration (1.94 mg/l) was recorded in the Chetpetpond during post monsoon season and the minimumconcentration (0.001 mg/l) was recorded in the allhabitats during all seasons. The minimum nitrite concentration (0.01 mg/l) was recorded at Chetpet pondduring pre monsoon and summer season respectively. Maximum nitrite concentration (2.57mg/l) was recordedat Chenglepet lake during premonsoon season. Thephosphate values varied between 0.001 to 3.50 ppm. The minimum phosphate values(0.001 mg/l)were found atChetpet pond during monsoonseason and Chenglepet lake during all seasons. The maximum phosphate concentration (3.50 mg/l) was recorded at Chetpet pondduring monsoon season. The average values of silicatevaried between 0.001 to1.60 mg/l. The minimumsilicate (0.001 mg/l) values were recorded at Chetpetpond during summer season and Chenglepet lake duringpost monsoon season and maximum silicate value (1.60mg/l) was recorded at Chenglepet lake during Postmonsoon season. Silicate producedthe highest and significant correlation with othervariables in the matrix during monsoon season. The principal component analyses and their loadings clearly bring out the role of urban environment onthe water chemistry of Chetpet and Madhavaram ponds.The components had clearly identified the processesand cross loadings are absent in the case ofChenglepet lake. A total number of 149 phytoplanktontaxa were identified from three major groups, theBacillariophyceae, Chlorophyceae, and Cyanophyceaeacross the three freshwater habitats. Chlorophyceaewas the dominant abundance (55,000 Cells/m3) during post monsoon season. Cyanophyceae (40,000 Cells/m3)dominant during monsoon season and Bacillariophyceae(13,000 Cells/ m3) was dominant abundance during premonsoon in Chetpet pond. A totalnumber of 235 zooplankton taxa were identified fromfour majorgroups Cladocera, Copepoda, Rotifera andOstracoda. Rotifera was the dominant group ofzooplankton foundin all habitats, represented by 95species across theall habitats. Rotiferea (55,000ind/ m3) was the dominant abundance in Chetpet pondduring monsoon season which is Copepoda (16,000 ind/m3) in Madhavaram pond during premonsoon and Cladocera(16,000 ind/ m3) in Cheglepet lake during summer season. According to thetropic index assessment methods of Wetzel and Carlsonwith Kolavoi lake, Chetpet pond and Madhavarampond data indicated hyper eutrophic conditionimmediate measures for restoration. Address for communication No.2. Thiruvalluvar salai, R.V.Nagar, Chennai -600118,India, Tamil Nadu Email: bharathikod@yahoo.com
key words: limnology,flora,fauna,tracemetal,PCA,CCA,Boxwhisker plots,intercorrelation matrix