Making mud pies in Sydney Harbour: manipulative experiments to untangle the effects of multiple stressors on estuarine communities.

Estuaries are diverse and productive ecosystems that are subject to high levels of disturbance from multiple human stressors. Chemical contaminants and nutrients from urban and industrial activities are released into estuaries and accumulate in bottom sediments where they may impact resident animals. To assess the ecological health of sediment animals, the common chemical contaminant stressors are usually targeted (e.g. the metals, PAHs and pesticides with guideline values), but fewer studies consider the influence of nutrient enrichment as well as contaminants.

A large collaborative effort bringing together SIMS researchers, including Dr. Katherine Dafforn with Southern Cross University, CSIRO and OEH scientists aims to address this gap and investigate the ecological relevance of toxic and enriching contaminants to help develop more targeted sampling programs.

Manipulative experiments are underway deploying sediments with varying levels of metal contamination and added fertilizer in benthic recruitment containers. The results will have implications for future management practices in estuaries and increase our understanding of the relative impacts on benthic estuarine communities of nutrients from terrestrial run-off and metal contamination from industrial practices.