Merri Creek

By assessing sediment quality, CAPIM isolated the primary land-uses responsible for degrading the ecological condition of the Merri Creek, thereby helping target management actions in the catchment.

Merri Creek highlighting agricultural activities that occur towards the top of the catchment.
Credit: Dave Sharley.
Merri Creek at Somerton. Credit: Dave Sharley.

Merri Creek

What was the problem?

Over the past 30 years, significant land-use changes have occurred within the Merri Creek catchment, with the middle and upper reaches of the catchment becoming increasingly urbanised, threatening some of Australia’s most vulnerable ecosystems. CAPIM conducted a study to identify the priority stressors affecting the health of Merri Creek to inform management actions within the catchment.

How did CAPIM address it?

Using a sediment quality triad assessment approach (sediment chemistry, sediment toxicity and benthic fauna assessment) in conjunction with land-use analysis of the catchment, this study enabled us to isolate the primary catchment activities degrading the ecological condition of the creek.

What was the outcome?

We were able to identify the link between land-use activities and sediment pollution. We found that point source pollution originated from industrial and new residential areas, and was likely to contribute to an increase in the toxicity of stream sediments and changes in the composition of the benthic fauna. Industrial areas were associated with increased heavy metal and hydrocarbon concentration while new residential areas were linked to increased synthetic pyrethroids levels, most likley due to pest-control applications.

We concluded that reducing the direct discharges of industrial run-offs into Merri Creek and the use synthetic pyrethroids in nearby residential areas would likely improve sediment quality and the ecological health of the creek. Findings from this study will help water managers target management actions within the catchment.

For more information on this study, please contact Associate Professor Vincent Pettigrove