The diversity and distribution of phytoplankton, zooplankton community structures were observed in relation to environmental parameters in the coastal waters of the Kayalpattinam coast, Southeast coast of India during February-March 2015. The physico-chemical parameters such as surface water temperature, TDS, Salinity, pH, Dissolved Oxygen, Conductivity were analyzed. The above values were 28.50±1.80⁰C, 30.93±1.46 (mg/l), 34.0±0.50ppt, 8.33±0.51, 7.09±0.68 (mg/ml), 11.63±0.71 (µs/cm), respectively. A total of 11 phytoplankton species and 17 zooplankton species were recorded and a total number of populations of phytoplankton and zooplankton species recorded were 87 and 122 respectively. Among the phytoplankton, the maximum percentages were covered by Coscinodiscus gigas (39.08%) followed by C.excentericus (28.74%), Oscillatoria (6.9%), Biddulphia mobilensis (4.6%) and Leptocylindrus danicus (4.6%). Similarly, the zooplankton population was dominated by species such as Copepod nauplii (29.51%), Oikopleuro dioica (28.69%), Oithona brevicornis (9.84%) Centrophages furgatus (5.74%). Both qualitative and quantitative abundance of phytoplankton and zooplankton communities in this coastal ecosystem are presented and discussed.