• Elsdon, Travis
• Gissi, Francesca
• Robertson, Tim
• Strzelecki, Joanna
• Hook, Sharon
• Golding, Lisa
• Adams, Merrin
• Binet, Monique

Abstract

Petroleum hydrocarbons can be accidentally released into the marine environment during off-shore oil and gas production or as a result of rare oil spills, with potential impacts to marine organisms.Depending on the release scenario, this chemical mixture may be quickly dispersed and diluted in the surrounding seawater and pose minimal risk to biota. Ecotoxciological assays used to characterise risk, expose organisms to durations (24, 28, 96 h) that do not reflect realistic environmental exposure durations (<2 h). To address this, we adapted toxicity tests to represent a short-term pulse exposure to produced water (PW) (discharged from oil rigs during production), or petroleum hydrocarbons from an accidental oil spill. We exposed the copepod, Acartia sinjiensis, a sea urchin Heliocidaris tuberculata and yellowtail kingfish embryos (Seriola lalandi) to PW and water accommodated fractions (WAF) from a condensate and crude oil, at different exposure durations, e.g., 2 h, 4 h, 24 h or continuously (i.e. the standard toxicity test duration, according to standard protocols), and concentrations. After exposure, organisms were transferred into clean seawater and the test continued as normal until continuous test exposure ended. We assessed 48 h survival for the copepod, 72 h larval development for the urchin and 48 h embryo development for the fish. Effects on copepod survival and sea urchin larval development were significantly reduced in the short-term exposures for PWs and WAFs compared to continuous exposures. Fish embryos however were observed to be sensitive to oil induced cardiac toxicity with an increased frequency of deformities at the elevated doses regardless of exposure duration, although there was a trend towards increased severity with continuous exposure. The tests demonstrate that exposure duration can alter toxic response and building exposure duration into ecotoxicology testing may aid interpretation of realistic effects and consequences.

Topics

• toxicity