Toxicity of crude oil and dispersed crude oil to ghost shrimpPalaemon serenus and larvae of Australian bassMacquaria novemaculeata

Abstract

Acute 96-h LC50 values of the water-accommodated fraction (WAF) of crude oil, dispersants (Corexit 9500 and Corexit 9527) and dispersed oil combinations were determined in semistatic bioassays with seawater, using the ghost shrimp Palaemon serenus and larval Australian bass (fish) Macquaria novemaculeata. Sodium dodecyl sulphate (SDS) and zinc sulphate were used as reference toxicants and identical bioassays were conducted using these compounds. Total petroleum hydrocarbon (TPH) uptake of shrimp was also measured on the samples taken from the bioassays. The nominal mean (n=4) 96-h LC50 standard error (SE) values for WAF of crude oil, Corexit 9527, Corexit 9500, dispersed oil (9527) and dispersed oil (9500) were 258,000 ppm (13,000), 49.4 ppm (6.4), 83.1 ppm (5.8), 8.1 ppm (0.3), and 3.6 ppm (0.3) in the shrimp bioassays, respectively. The nominal mean (n=4) 96-h LC50 (SE) values calculated from the fish larval bioassays were 465,000 ppm (16,000), 14.3 ppm (0.9), 19.8 ppm (1.6), 28.5 ppm (1.4), and 14.1 ppm (2.6) for WAF of crude oil, Corexit 9527, Corexit 9500, dispersed oil (9527), and dispersed oil (9500), respectively. These LC50 values indicate that dispersed oil combinations were significantly more toxic to these organisms than WAF of crude oil. TPH uptake of shrimp increased in correlation to exposure concentrations, and the presence of dispersant made oil more available for shrimp. © 2000 John Wiley & Sons, Inc. Environ Toxicol 15: 91–98, 2000