RESUMEN
An investigation was made on total heterotrophic bacterial (THB) load in relation with hydrographical features of Pazhayakayal estuary, Tuticorin, from July 2009 to June 2010. The water temperature (25 to 32oC), pH (7 to 10), and salinity (0‰ to 35.7‰) were maximum during summer season (April - June) and minimum during monsoon season (October - December). The dissolved oxygen (do) varied from 0.2 to 9.95 mg l-1. The THB load was high (42.0?0-7cfu ml-1) during monsoon season and low (1.2?0-7cfu ml-1) during summer. The correlation was insignificant between temperature, pH and THB load, however THB load was negatively correlated with salinity. Almost in all the stations (I-VI), THB load were found to be maximum (40.0?0-7,36.0?0-7, 30.0?0-7,36?0-7, 42.0?0?0-7 and 29.6?0-7 cfu ml-1) during monsoon season might be due to the bulk rainfall and freshwater input.