Biomarker Response of Pink Snapper to Chronic Exposure to Synthetic-Based Drilling Muds

In Western Australia, the discharge of drill cuttings at sea is permitted under certain conditions set by regulatory authorities. These drill cuttings are coated with the drilling muds used during the drilling process. Synthetic-based drilling muds (SBMs) are increasingly used in exploration drilling. However, very little is known of their long-term toxicity in the marine environment. The impetus for the present study arose from the concerns raised regarding the long-term environmental impacts of SBMs on marine biota. The project investigated the chronic toxicity of two SBMs, Syndrill 80:20 and Syndrill 90:10, to a marine fish, the pink snapper (Pagrus auratus Forster). Juvenile fish were exposed under laboratory conditions to the two SBMs for 21 days, after which biomarkers of exposure (ethoxyresorufin-O-deethylase [EROD] activity and biliary metabolites) and biomarkers of effects (condition factor, liver somatic index, serum sorbitol dehydrogenase [SDH], DNA damage and heat shock stress proteins HSP-70)...