Organic pollutants in mussels and sediments of the coastal waters off Perth, Western Australia

The results of a survey of organic pollutants in the marine sediments and the common mussel, Mytilus edulis, from the southern metropolitan coastal waters off Perth are presented. Organophosphorus and organochlorine pesticides, polychlorinated biphenyls, aliphatic and polycyclic aromatic hydrocarbons and organotin compounds were analysed in surficial (top 20 mm) sediments from 175 sites and in mussel tissue from 35 sites over an area of 500 km2. Detectable concentrations of pesticides, polychlorinated biphenyls and aliphatic hydrocarbons were recorded at approx. 5% of the sediment sites and 10% of the mussel sites. Contamination was generally confined to areas within or immediately adjacent to shipping facilities and marinas. By contrast, contamination of sediments and mussels with polycyclic aromatic hydrocarbons and organotin compounds, particularly tributyltin, was widespread throughout the study area. Areas of highest contamination occurred in harbours and boat mooring areas and along the eastern side of Cockburn Sound. Comparisons with the results of similar Australian and overseas studies indicate that, in general, sediments and mussels from these waters are not significantly contaminated with pesticides, polychlorinated biphenyls or hydrocarbons. In contrast, elevated concentrations of tributyltin in the sediments and mussels are amongst the highest recorded in Australia and, coupled with the known toxicity of this compound to marine animals, are cause for major concern. The high frequency of imposex in the neogastropod, Thais orbita, collected from the study area underlines this concern.