Effects of sewage effluent on 'pulse' infaunal assemblages.

This experiment tested the effects of secondary treated sewage effluent on infauna assemblages that were taken from a 'reference' site immediately after a large dump of macroalgae had cleared from the mudflat. Macroalgae cover can have severe effects on infaunal assemblages so it was expected that the recent macroalgae dump would affect the responses of infauna to the effluent dosing. Twelve intact sediment cores were collected from this site on the Western Treatment Plant foreshore (Port Phillip Bay, Victoria) and brought back to the laboratory. Four cores were assigned to each of the two treatments, which were high dose (7mls effluent per minute) or no dose of effluent. The experiment ran for 13 days in October 1999.

Throughout the experimental period, dissolved oxygen levels were measured and animals that migrated from the sediment were collected, counted and identified. At the end of the experiment, sediment chlorophyll levels were measured and infauna remaining in the sediment were counted and identified.