TIDAL AREA DISPERSANT EXPERIMENT, SEARSPORT MAINE: AN OVERVIEW

On August 19, 1981, two test spills of Murban crude oil were carried out in Long Cove, Searsport, Maine. One spill was chemically dispersed; the other was not. Measurements were made to make quantitative comparisons of the chemical fates and biological effects of the two spills. Hydrocarbon analyses were carried out on water samples, animal tissue samples, intertidal sediment samples, and subtidal sediment samples. Biological measurements were carried out at the community level, whole animal level, and biochemical level of organization. No significant biological effects attributable to the dispersed oil spill were observed. This lack of effects is, in part, a result of changes in the physical and chemical properties of dispersed oil which help limit its availability and toxicity. The chemical fate and biological effects of the undispersed oil spill were typical of those reported from actual oil spill sites. Oil was incorporated into sediments and animal tissue. On the community level of organization mortality, reduced diversity and evenness, increased population density, and increased dominance by opportunists were all observed immediately after the spill, and up to 1 year later. On the whole animal level of organization, no effects on scope-for-growth were observed in two filter feeding bivalves. On the biochemical level of organization, activities of two sensitive enzyme systems were elevated.