What does impacted look like? high diversity and abundance of epibiota in modified estuaries

Graeme F. Clark, University of New South Wales
Brendan P. Kelaher, Southern Cross University
Katherine A. Dafforn, University of New South Wales
Melinda A. Coleman, NSW Department of Primary Industries
Nathan A. Knott, NSW Department of Primary Industries
Ezequiel M. Marzinelli, University of New South Wales
Emma L. Johnston, University of New South Wales

Document Type Article


Ecosystems modified by human activities are generally predicted to be biologically impoverished. However, much pollution impact theory stems from laboratory or small-scale field studies, and few studies replicate at the level of estuary. Furthermore, assessments are often based on sediment contamination and infauna, and impacts to epibiota (sessile invertebrates and algae) are seldom considered. We surveyed epibiota in six estuaries in south-east Australia. Half the estuaries were relatively pristine, and half were subject to internationally high levels of contamination, urbanisation, and industrialisation. Contrary to predictions, epibiota in modified estuaries had greater coverage and were similarly diverse as those in unmodified estuaries. Change in epibiota community structure was linearly correlated with sediment-bound copper, and the tubeworm Hydroides elegans showed a strong positive correlation with sediment metals. Stressors such as metal contamination can reduce biodiversity and productivity, but others such as nutrient enrichment and resource provision may obscure signals of impact.