Coliform and escherichia coli bacteria in seawater around penang island, Malaysia

Abstract

The concentrations of coliform and Escherichia coli bacteria were determined in inshore seawater from 15 different areas, embracing more than three quarters of the coastline of Penang Island. Each area included from 3 to 20 sampling sites, each of which was sampled on at least two occasions, once at high tide and once at low tide. Samples were collected from water 100–150 mm below the surface and where, in most cases, the total water depth was about 0.6 m. Logarithmic mean concentrations in samples from areas with hinterlands having small or large human (and/or domestic animal) populations ranged from 493 to 712,000 coliform bacteria and from 72 to 234,700 E. coli bacteria per 100 ml. Samples from an area with a hinterland of natural forest and very few dwellings contained logarithmic mean concentrations of 31 coliform and less than 7 E. coli bacteria per 100 ml. The highest concentrations found in any sample from this area were 1100 coliform and 93 E. coli bacteria per 100 ml. It is suggested that the bacterial concentrations in seawater from this area may approximate to ‘base-line’ contamination levels. The overall results are considered in relation to standards applied elsewhere to bathing waters and to those applied to waters for shellfish culture.