| Fuel oil #6 is the current fuel used for the production of electrical power in the United States. An alternative fuel, called Orimulsion ®, is currently used in Canada, Denmark, Italy, and Japan, and is being considered for use in the United States. The decision of whether to use Orimulsion and of how to regulate its use depends on an accurate estimate of its value and risk, relative to fuel oil #6. This study examined the relative impact of accidental spills into the marine environment of fuel oil #6 and Orimulsion on the microalgal and meiofaunal communities. A microcosm system was developed for the shallow, sandy, subtidal environment and maintained for three months in the laboratory. Treatment microcosms were dosed with a single application of hydrocarbon-coated sand and sampled at intervals throughout the experiment. As indicators of effect on microalgae, I considered microalgal abundance, chlorophyll a to phaeopigment ratio, primary production, and phospholipid to neutral-lipid ratio. As indicators of effect on meiofauna, I considered copepod and nematode abundance and grazing rate as well as copepod species diversity, sex ratio, fecundity, age structure, and neutral-lipid content. Through day 74, abundance of microalgae and nematodes remained the same and abundance of copepods increased (a release from predation). On day 88, the abundance of both meiofaunal taxa declined, indicating the end of the useful duration of these microcosms. A comparison of the hydrocarbon treatments showed no significant differences. The test had adequate power to detect ecologically significant changes. This experiment indicates that a spill of Orimulsion would have approximately the same impact as a spill of fuel oil #6. |
