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

• Published in: Environmental pollution (1987) Vol. 196; pp. 12 - 20
• Main Authors: Clark, Graeme F., Kelaher, Brendan P., Dafforn, Katherine A., Coleman, Melinda A., Knott, Nathan A., Marzinelli, Ezequiel M., Johnston, Emma L.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.01.2015
• Subjects: Algae; Animals; Aquatic Organisms - classification; Aquatic Organisms - growth & development; Assessments; Australia; Biodiversity; Bioindicators; community structure; Conservation of Natural Resources; Contamination; copper; Correlation; Ecosystem; ecosystems; Environmental Monitoring; Estuaries; fauna; Geologic Sediments - chemistry; Human Activities; humans; Hydroides elegans; industrialization; Introduced species; Invertebrates - classification; Invertebrates - growth & development; Metals; Metals - analysis; Nutrients; Pollution; Pollution abatement; Polychaeta; prediction; sediment contamination; Sediments; South Australia; Stems; tube worms; urbanization; Water Pollutants, Chemical - analysis; South Australia; Australia; Nutrients; Pollution; Introduced species; Bioindicators; Biodiversity; Metals
• ISSN: 0269-7491; 1873-6424; 1873-6424
• DOI: 10.1016/j.envpol.2014.09.017

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. •We measured recruitment of epibiota in heavily modified and unmodified estuaries.•Tested for trends in epibiota relative to modification and environmental covariates.•Species richness and cover were similar with respect to human modification.•Less variation in community composition between modified than unmodified estuaries.•Human impacts may cause biotic convergence, reducing beta diversity. Epibiotic communities in heavily modified estuaries were similar in species diversity and abundance to those in relatively pristine estuaries.