Exxon Valdez oil spill restoration project final report

Auke Bay Laboratory (Juneau, Alaska)

Many mussel beds in the spill area, particularly those on soft sediment, were not cleaned immediately after the Exxon Valdez oil spill in 1989. Consequently these beds had high concentrations of contaminated sediments and tissues. Surveys documented the geographic extent (primarily Prince William Sound and the Kenai Peninsula) and intensity of oiling. Hydrocarbon concentrations declined naturally from 1992-1995 in some. but not all beds. Distribution of oil in sediments was related to tidal elevation, depth, and grain size. Oil concentration in mussels correlated with that in sediment. Mussel condition was adversely affected by oil; prevalence of digestive gland metaplasia, brown cells, and hemocytic infiltrates ingonads increased, and storage cell abundance decreased. However, some physiological responses (byssal thread production, condition index, feeding rate. or glycogen content) in mussels contaminated 3-4 years were not correlated with oil concentration. Bed restoration caused immediate reductions in oil concentration in surface sediment, but these sediments were later partially recontaminated by remaining oil. Restoration efficacy was less evident in mussels: Concentration reductions were significant in less than half the beds by the end of study. Mussel densities declined in one-half of the beds alter restoration, hut density declines were similar in untreated reference beds.

Miscellaneous

National Marine Fisheries Service (NMFS)