The effects of three petroleum products on Pacific oysters (Crassostrea gigas)

Canada is one of the largest producers and exporters of petroleum products in the world. With the rapidly increasing petroleum transportation planned through marine routes in North America, understanding the toxicological repercussions of petroleum exposure and risk to wildlife is essential. Pacific oysters (Crassostrea gigas) were selected as a model bivalve species to determine the ecological implications of potential petroleum spills using marine diesel (MD), crude oil (CO), and diluted bitumen (DB). Toxicity endpoints included the scope for growth (respiration rates, food assimilation, and clearance rates), condition index, health assessment index, gonadal and digestive gland histopathology, as well as larval development. CO water-accommodated fractions (WAFs) contained the highest initial total polycyclic aromatic compound (TPAC) concentrations (350 µg/L), followed by MD (150 µg/L) and DB (128 µg/L). Oyster tissue TPAC concentrations reflected these trends; CO (29 µg/g), MD (4 µg/g), and DB (3 µg/g). No WAF or time-related effects were observed on the measured endpoints in Pacific oysters following a sub-chronic exposure to WAFs of CO, MD, or DB. These results suggest that despite being used as a biomonitor species in the past, Pacific oysters do not retain TPACs for long durations after being removed from a petroleum spill. Consequently, further studies with different exposure conditions and bivalve species are required to assess the impact of these contaminants in a marine environment.