Acute toxicity of crude and dispersed oil to Octopus pallidus (Hoyle, 1885) hatchlings

Abstract

There is an increasing risk of a major oil spill in Australian waters over the next 20 years but there have been few studies on the impact of oil spills, and subsequent remedial action, on native Australian fauna. Octopus pallidus is a native Australian octopus species found in south-eastern Australia. The aim of the experiment was to investigate the effects of acute exposure to crude and dispersed crude oil and 4-chlorophenol (a reference toxicant) on recently hatched O. pallidus by calculating the 48-h LC50. Water-accommodated fraction (WAF) of Bass Strait crude oil was prepared using a ratio of one part crude oil to nine parts filtered seawater and mixing for 23 h. Dispersed-WAF was prepared using a ratio of one part Corexit 9527 to 50 parts crude oil and an oil to water ratio of one to nine and mixing for 23 h. Mean (SE) 48 h LC50 values were 0.39 (0.04), 1.83 (0.64) and 0.89 (0.08) ppm for WAF, dispersed-WAF and 4 chlorophenol, respectively. These results demonstrate that addition of the chemical dispersant Corexit 9527 to WAF does not increase the toxicity of WAF to O. pallidus hatchlings.