RESUMO
Distribution of major groups of enteric bacteria viz., Escherichia coli, Shigella spp., Salmonella spp., Vibrio parahaemolyticus and Vibrio cholerae was studied in the sediment samples collected from different depths of 5, 15, 25 and 35 m in Parangipettai and Cuddalore coast during March, 2009 to February, 2010. Among the bacterial population in Parangipettai, V. parahaemolyticus was found to be maximum with an occurrence of 55% followed by Shigella spp. (15%), V. cholerae (12%), Salmonella spp. (12%) and E. coli (6%). In Cuddalore, as an oddity, Vibrio cholerae emerged as dominant species with an incidence of 60% of the total. V. parahaemolyticus came next in the order with an incidence of 14%, followed by E.coli (11%), Shigella spp. (8%) and Salmonella spp. (7%). Similarly, monsoon and premonsoon seasons registered higher bacterial populations in both the regions. When the depth wise results were viewed, 5 and 15 m depths showed maximum (V. parahaemolyticus 3.7x 10 CFU g-1 in Parangipettai; V. cholera - 8.6x10 CFU g-1 in Cuddalore) bacterial population compared to subsequent depths. Cluster and MDS also showed distinct spatial and seasonal variations of bacterial populations in both the regions. Biota-Environment (BIO - ENV) method revealed the combinations of temperature, salinity and TOC as the best match influencing bacterial population.