International Science Community Association Research Journal of Marine Sciences 2321 - 1296 1 1 2013 April 8 Seasonal variability of Ulva species (Green seaweed) in Tirunelveli region, the south east coast of Tamil Nadu, India 14 17 EN John Peter Paul J 1 PG and Research Department of Botany, St. Xavier’s college (Autonomous), Palayamkottai–627 002, Tamil Nadu, INDIA S.D.K. Shri Devi 2 Department of Botany, Sri Sarada College for Women (Autonomous), Salem–636 016, Tamil Nadu, INDIA > Research Paper 2013 3 21 2013 April 8 The present study was carried out to explore the seasonal variation of Ulva species in Tirunelveli region, the south east coast of Tamil Nadu, India. Tirunelveli region was divided in to four stations namely Kootapuzhi, Perumanal, Idinthakarai and Koothankuzhi for the collection and identification of seasonal variability of Ulva species. Monthly survey was conducted regularly for a period of four years from January 2007 to December 2010. The Ulva species were enumerated at random using a quadrate (0.5m2 ). A total of four species of Ulva were collected in the study area such as Ulva fasciata, Ulva intestinalis, Ulva lactuca and Ulva reticulata. The frequency and density were calculated and all the Ulva species showed a similar pattern of seasonal variation. Among the seaweeds collected the highest frequency (71.25%) and density (5.41) were observed in Ulva intestinalis during summer season and the lowest frequency (41.75%) and density (2.75) were recorded in Ulva reticulata during post monsoon season. From the present study it was concluded that all the Ulva species (Chlorophyceae) exhibited the maximum frequency and density during the summer season followed by the declined trend was observed in the successive seasons. During the post monsoon season the frequency and density of Ulva species (Chlorophyceae) was minimum in the selected region of south east coast of Tamil Nadu. Copyright@ International Science Community Association