3044 Environmental Toxicology and Chemistry, Vol. 22, No. 12, pp. 3044–3048, 2003  2003 SETAC Printed in the USA 0730-7268/03 $12.00 + .00 SUBLETHAL EFFECTS OF ORIMULSION-400 ON EGGS AND LARVAE OF ATLANTIC HERRING (CLUPEA HARENGUS L.) JIM WILLIAMS,*² C AROL RODERICK,² and R OSS ALEXANDER‡ ²Biology Department, Saint Francis Xavier University, P.O. Box 5000, Antigonish, Nova Scotia, Canada B2G 2W5 ‡Department of Fisheries and Oceans, P.O. Box 5030, Moncton, New Brunswick, Canada E1C 9B6 ( Received 21 August 2002; Accepted 9 May 2003) Abstract—Orimulsion-400 is a novel bitumen-emulsion power plant fuel. We exposed Atlantic herring (Clupea harengus L.) eggs to 0, 0.1, 1.0, 10, 100, and 1,000 mg/L concentrations of an oil-in-water dispersion of Orimulsion-400 for a 24-h period. No significant differences were found in daily mortality or percent hatch. The 1,000 mg/L exposure resulted in a significantly higher incidence of premature hatch, indicated by significantly shorter incubation time, significantly smaller total length and notochord length, and significantly greater yolk sac depth. The larvae exposed to the 1,000 mg/L treatment also had a significantly higher incidence of abnormalities than all other treatments. Keywords—Orimulsion Atlantic herring Eggs Larvae Sublethal effects INTRODUCTION Orimulsion-400 (PDVSA-BITOR, Caracas, Venezuela) is a Venezuelan fuel, marketed for use in thermal generation stations as an economical and environmentally friendly alter- native to Fuel Oil No. 6 or coal. Orimulsion-400 is a surfactant- stabilized emulsion consisting of approximately 70% Orinoco Belt bitumen and 30% water [1]. The only power plant in North America that presently burns Orimulsion-400 is located in Dalhousie (NB, Canada), where the New Brunswick Power Corporation (NB Power) has committed to a 20-year contract for tanker delivery of up to 800,000 metric tons of Orimulsion- 400 annually [2]. On November 1, 2001, NB Power announced that it had filed an application with regulatory agencies to refurbish a second power generating station at Coleson Cove (NB, Canada) to begin burning Orimulsion-400 by 2004. If spilled in water, the physical properties of Orimulsion- 400 result in behavior quite different from that of conventional fuel oils [1]. Because of the surfactant, Orimulsion-400 ini- tially disperses and forms a cloud of suspended individual bitumen particles throughout the water column. The aqueous component, which contains most of the hydrocarbons that can be solubilized from the bitumen particles as well as the sur- factant, eventually diffuses throughout the receiving body. The behavior of the suspended bitumen particles over time depends largely on salinity, temperature, and turbulence. In fresh water, the bitumen particles tend to sink, whereas at high salinities, the bitumen particles tend to coalesce and rise to the surface. In brackish water, studies have concluded that the movement of the bitumen in the water column is very difficult to predict [1,3] because even small changes in temperature and salinity have drastic effects on the relative densities. Agitation from waves or currents affects the rate at which all processes take place, and in a dynamic receiving environment, the bitumen particles can spend considerable time mixed in the water col- umn. If the bitumen particles coalesce and rise to the surface, their movement will be influenced primarily by wind, similar * To whom correspondence may be addressed (jwilliam@stfx.ca). to other hydrocarbon slicks. Cleanup at this stage can be com- plicated by the extremely high viscosity of the bitumen, ren- dering many conventional cleanup methods ineffective. The marketing company Bitor (Boca Raton, FL, USA) has recently demonstrated what it considers to be effective recovery tech- nology, but that process requires high temperatures and air injection to be effective. Concern has been expressed by some that this might not be a practical solution for anything but minor spills. Given the potential for extensive dispersal of bitumen in the event of an Orimulsion-400 spill, research ex- amining the potential effects on organisms in the receiving environment is clearly needed. The present study examines the effects of Orimulsion-400 on eggs and larvae of the Atlantic herring (Clupea harengus), a commercially important pelagic fish. The Baie des Chaleurs area adjacent to Dalhousie, where the NB Power generating station is located, is a valuable spawning area for the Atlantic herring [4]. Herring eggs are attached to seaweed and substrate in the intertidal and subtidal zones [5,6], with highest egg concentrations at depths of 1.4 to 4.0 m [7]. Given the spawn- ing period and incubation time, herring eggs would be vul- nerable to exposure to Orimulsion-400 as many as three months of the year in the event of a spill. MATERIALS AND METHODS Eggs of three female herring were stripped, mixed, and fertilized using pooled sperm of five males. Fertilized eggs were allowed to adhere to the bottom of petri dishes, with approximately 250 eggs per dish [8]. Petri dishes containing approximately 35 ml of filtered seawater (salinity 30‰) were incubated at 5°C, with daily water changes using prechilled, filtered seawater. Blastula-stage herring eggs were exposed to five concentrations of Orimulsion-400 in the following manner. Oil-in-water dispersions of Orimulsion-400 were prepared by adding seawater to a weighed quantity of the emulsion [9]. Nominal concentrations of 0.1, 1, 10, 100, and 1,000 mg/L were prepared, although the final concentrations were some- what lower because of the tendency of the Orimulsion-400 to