A Study of the Effects of the San Francisco Oil Spill on Marine Organisms

Abstract

ABSTRACT The San Francisco oil spill occurred on January 18, 1971, during the early morning hours when two Standard Oil vessels collided almost directly under the Golden Gate Bridge, releasing 840,000 gallons of Bunker C fuel. This asphalt-like oil was washed up on intertidal shores of the area. Duxbury Reef, northwest of the Golden Gate Bridge, is literally the “backyard” of the author and the College of Marin's Bolinas Marine Station staff. Baseline transects have been established on this reef since 1958. The oil was heavily deposited on the reef's mussel beds and high tidal berm rocks. From comparative transect and laboratory observations, it was determined that marine organisms died from being smothered by the oil, with certain species, such as acorn barnacles and limpets, suffering the highest mortality at Sausalito and on Duxbury Reef. Comparison of pre-oil and post-oil transect counts showed there was a significant decrease in marine life after the oil spill on the reef Marine snails suffered less mortality than the sessile barnacles and other sedentary animals. The normally large population of striped shore crabs is missing from the rocky crevices. Finally, marine algal blooms were also observed in certain reef localities. The present condition of Duxbury Reef (December, 1971) is one of apparent good health; the recruitment of some marine animals appear to be approaching normal levels. The oil has disappeared from much of the reef surfaces and is barely discernible in the most heavily deluged areas. Continued studies will be aimed at watching the effects of oil on the recruitment of marine life throughout the afflicted areas of the Marin County coastline.