IMPACTS ON INTERTIDAL INFAUNA: EXXON VALDEZ OIL SPILL AND CLEANUP

ABSTRACT Field surveys were conducted throughout Prince William Sound in the summers of 1990 through 1992 to evaluate recovery of infauna from the effects of oiling and shoreline cleaning treatments following the Exxon Valdez oil spill. Infauna were quantitatively sampled at mixed sand/gravel/cobble beaches categorized into treatment groups according to their general degree of disturbance.Category 1: unoiled reference sitesCategory 2: oiled sites, not hot-water-washedCategory 3: oiled sites, “cleaned” with hot-water flushes Shoreline treatments applied in 1989 and 1990 had varied effects on intertidal infauna including organism displacement and burial, thermal stress, oil dispersion, and transformed beach morphology. These treatments resulted in significant reductions in infauna (total abundance and diversity, as well as densities of polychaetes, bivalves, and some crustaceans) at Category 3 beaches. In contrast, Category 2 beaches had a richer and more varied infauna than Category 3 beaches. Multivariate analyses indicate some trends in recovery: namely, a convergence by certain Category 2 sites toward the Outside Bay, Category 1 control site. PAH concentrations in 1990 also suggest that treatments acted to move some hydrocarbons downslope from the upper beach into the shallow subtidal. By 1991, PAH concentrations in the shallow subtidal were no longer at the high levels seen in 1990, but PAH levels at other elevations of Category 3 sites remained at about the same levels as in 1990.