A Biological Survey of Oil Platforms in the Santa Barbara Channel

Abstract

During 1975 biologist-divers surveyed the marine life found on and near two offshore structures in the Santa Barbara Channel. The detailed biological and chemical inventory performed showed a great abundance of many specks, large sizes of some organisms, and a lack of contamination. Introduction The objectives of the studies reported in this paper were to obtain facts about the present status of the sea life on and near two offshore structures and to compare the quantity and quality of life there now with that which lived at the towers several years ago and with that at nearby control sites. The undisturbed muddy and rocky bottoms that were used for controls offer conditions similar to those that would exist if the platforms had not been built. Studies of the biology of both platforms by California Dept. of Fish and Game biologists in 1960 and 1970 provided historical data for comparison. Having made repeated direct observations, measurements of oceanographic parameters, precise chemical analyses of many samples, and extensive biological studies, we found that life on and around the two platforms is healthy and shows no indication of the uptake of any toxicant. Species diversity and abundance are greater than at the control sites. The number of fish now living under each platform is 20 to 50 times the number that lived in the area before construction. Platforms Hilda and Hazel were installed by the Standard Oil Co. of California in 1958 and 1960, respectively. These structures are about 100 ft (34 m) square and stand in water depths of about 100 ft (31 m) about 2 nautical miles south of Loon Point in the Santa Barbara Channel (Fig. 1). Of the 25 wells drilled from Hazel, eight are now producing 290 B/D of 28- to 40-degrees API-gravity oil. Of the 24 wells drilled from Hilda, seven are now producing 318 B/D of similar crude. No special precautions were taken to prevent pollution during the uneventful development of this field. The cuttings were dumped in a heap on the sea floor under the platforms, where they make broad cones about 5 m high (to which 1 meter of mussel shells has been added). Shortly after the platforms were installed, marine biologists began to study the effects of these new manmade reefs by diving to make direct examinations. Fish counts and collections of organisms were made over a 29-month period. The scientists found (1) 47 species of fish, 40 species of invertebrates, and 14 species of algae around the platforms; (2) little life on the cuttings pile; and (3) the fish population under Hazel stabilized at 6,000 fish (after a temporary peak at 62,000 fish caused by schools of transient fish). In Aug. 1970 another group of California Fish and Game biologists resurveyed the site and found the resident fish population had increased to 12,500 under Hilda and 18,000 under Hazel. Numerous other biological studies of the area made after the Santa Barbara oil spill of Jan. 1969 (from Platform A, only about 4 miles away) did not address the question of the resident platform fauna. In early 1975 the Southern California Coastal Water Research Project received a grant from the Institute of Marine Resources of the U. of California to update the past work and investigate more thoroughly the effects of these platforms on marine ecology. The Institute of Marine Resources was in turn supported by API. JPT P. 1280^