The effects of domestic sewage effluent on marine communities at Coffs Harbour, New South Wales, Australia

Studies of the impact of secondary treated domestic effluent have been conducted at Coffs Harbour, NSW, Australia for the last 8 years. During that time, monitoring has shown that impacts are restricted to within approximately 300 m of the outfall for most variables (e.g. algal species richness, changes to the structure of invertebrate communities living in kelp holdfasts) but that the ephemeral green alga Ulva lactuca has significantly greater cover than at reference sites for a distance of 500 m from the point of discharge. Based on the results of this study, a new outfall proposed for the northern area of Coffs Harbour was predicted to have effects over a much smaller spatial scale. It is suggested, therefore, that the recent decision to abandon the plans for the new outfall reflects growing public concern over issues other than cost minimization and biological impact in the use of ocean disposal as an option for the management of human sewage waste.