Bacterial Flora of the Water and Sediment in the Edo River Mouth

Abstract

Bacterial flora of the water and sediment in the Edo River mouth, a highly polluted area, was bimonthly investigated from May 1980 to March 1981. Six different agar media were used aerobically and anaerobically. The anaerobic water mass, called “Aoshio”, was observed at the depth of 10 to 15 m from May to July.
In the water column, total viable counts ranged from 10³ to 10⁵ ml^-1, and aerobic gram-negative bacteria, Acinetobacter, Moraxella, Pseudomonas, Flavobacterium and Vibrio-Aeromonas, were vertically, horizontally and seasonally predominant. In spite of the anaerobic condition in bottom water, few anaerobes and many aerobes were isolated from the water in May and July.
In the sediment, total viable counts were 10⁶ g^-1, and aerobic gram-negative bacteria and sporeformers, Bacillus and Clostridium, were seasonally predominant.
The presence of aerobes in the anaerobic water layer and bottom sediment suggests their sedimentation from the upper layer.