Distribution of Heterotrophic Bacteria in Vellar Estuary, East coast of India

Abstract

Density (x 10³.ml^-1)of heterotrophic bacterial population was highest (10.9) in marine zone followed by gradient (3.75),freshwater (3.4)and tidal (1.9) zones of the estuary, <i>Vibrio, Pseudomonas, Micrococcus, Bacillus</i> and <i>Alcaligene</i>s were the most commonly encountered genera. Particulate organic carbon values (mgC.1^-1 were high in marine zone (0.665) followed by the gradient, freshwater and tidal zones. Higher values of POC coincided with the higher densities of both phytoplankton and bacteria. Chl.<i>a</i> varied from 0.005 to 0.018 mg.m^-3, registering higher value in the gradient zone and lower value in the freshwater zone. Higher density of phytoplankton population was encountered from the marine zone (2,480 cells.1^-1) followed by gradient, tidal and freshwater zones and the phytoplankton density decreased with fall in salinity.