Abstract:

Marine diesel oil (MDO) is a ubiquitous fuel used by marine traffic on all coasts of Canada. Despite its common use, its environmental effects in the event of spills are difficult to predict due to the variation in its composition. The Haíɫzaqv (Heiltsuk) First Nation has identified the need for better understanding of the effects of MDO due to its presence in vessels in their territory (and the broader coast), to inform stewardship work and mitigation of any potential spills. In MDO, polycyclic aromatic compounds (PACs) are attributed as the primary toxic ingredients. Testing the effects of individual PACs can allow for modelling of overall impacts of petroleum products on a given species. The species of interest in this study, the Pacific purple sea urchin (Strongylocentrotus purpuratus), was chosen due to ecological and cultural significance to the Haíɫzaqv First Nation. Consequently, in collaboration with and at the request of the Haíɫzaqv Nation, this study is assessing acute toxicity of 5 individual PACs on the purple sea urchin by investigating the effects on behaviour. The individual PACs used cover a range of affinities for lipids, described by octanol-water partition coefficient values (logKOW; 2.9-4.5). Sea urchins were exposed to artificial seawater with known concentrations of PACs present over a 48-hour period. A righting response assay was used to quantify the effect of PAC exposure on urchin vigour. Preliminary findings of behavioural tests will be presented, along with predictions on how PACs combined might affect urchins and the broader marine environment.