Comparison of the abundance of the fecal sterol coprostanol and fecal bacterial groups in inner-shelf waters and sediments near Sydney, Australia

Abstract

Concurrent measurement of the sewage tracer coprostanol and fecal indicator bacteria were made for water and sediments collected in January 1992 from coastal waters off Sydney, Australia. The coprostanol results were compared with data from an earlier survey conducted in 1989 before the commisioning of Sydney's deepwater ocean outfalls in 1990 and 1991. Good correlations were observed for both water and sediment samples between coprostanol and the two fecal indicator organisms, fecal coliforms and Clostridium perfringens spores, thereby validating the use of coprostanol as a sewage signature in this environment. For sediments, most inner-shelf sites (1–10 km offshore) showed an increase in the concentration of coprostanol between the two surveys. The areas of highest concentration have been shifted further off-shore, to zones adjacent to the diffusers.