Blue mussels (Mytilus edulis) as bioindicators of stable water quality in Sydney Harbour during remediation of the Sydney Tar Ponds, Nova Scotia, Canada

Contaminants were measured in blue mussels (Mytilus edulis) in Sydney Harbour (SH) during remediation of the Sydney Tar Ponds (STPs) to assess the spatio-temporal distribution of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and metals during baseline and remediation. Overall distribution of chemicals in mussels was compared to contaminants in other marine indicators. Metal concentrations in mussels showed some minor temporal variability, but did not appear to be directly related to remediation activities. Contaminants showed stable or decreasing concentrations, except Pb and Zn. Individual PAH compounds were mostly undetected, except for fluoranthene and pyrene. Concentrations of fluoranthene in mussels and water were weakly related (R2 = 0.72). PCBs were undetected, except during year 2 remediation at some near-field stations. Contaminants measured during this study were much lower than previously reported in other studies of mussels in SH, likely due to ongoing natural recovery and because of environmental mitigation measures implemented during remediation activities at the STPs. The lack of detection of most individual PAHs, PCBs, and low bioaccumulation of metals during baseline and remediation using mussels as bioindicators reveal subtle improvements in environmental quality in SH.