Abstract:

The Nathan E. Stewart tug barge sank on the coast of British Columbia resulting in 110 000 L of marine diesel oil (MDO) and other oil products to spill into waters within Haíɫzaqv (Heiltsuk) First Nation territory. The lack of recovery of the surrounding bivalve populations since has highlighted our limited knowledge of the impact of oil products to these animals. Understanding the biological effects of individual aromatic compounds (ACs) can allow for modelling of the overall effects of oil products to bivalves. This study investigated the acute aquatic toxicity of five ACs to juvenile and adult life stages of Manila clams (Ruditapes philippinarum) using a passive dosing system design. The ACs chosen were styrene, naphthalene, 1-methylnaphthalene, dibenzothiophene, and phenanthrene, and covered mono- and polycyclic classes of ACs within a range of log octanol-water partition coefficient (Kow; 2.9-4.5) values. The passive dosing system design used PDMS O-rings to administer detectable and uniform concentrations of hydrophobic ACs into aquatic environments. Parallel water samples were collected throughout the test period and the analytically confirmed concentrations were used to analyze time-dependent median lethal/effect concentration (L/EC50) values in prepared seawater. All tested individual ACs had significant effects to juvenile R. philippinarum survival with a positive correlation between the toxicity and Kow values. These results were used as a basis to determine methods for adult toxicity testing and preliminary results will be discussed.