Biological study of oil platforms Hilda and Hazel, Santa Barbara Channel, California

Abstract

During 1975, surveys were conducted on the marine life around platforms Hilda and Hazel in the Santa Barbara Channel, southern California.

From the Abstract: "The platform fauna was characterized by an abundance of fish (20,000 to 30,000 of over 45 species) and a heavy growth (up to four feet thick) of attached mussels, anemones, corals, startfish, bryozoans and other invertebrates on platform structures and cuttings piles (tailings). Benthic samples taken at one platform revealed a diverse polychaete fauna including a bed of Dioptra tube worms surrounding the cuttings pile. The polychaete fauna was enhanced in the direction of prevailing subsurface currents, suggesting biostimulation resulting from discharge of organic mateial from the platform organisms.

There were 20 to 50 times more fish under the platforms than at the soft bottom control area of comparable size, and species diversity was similar to a rocky (hard bottom) control site.

Metals and petroleum hydrocarbon levels in platform fish and invertebrates showed no increase over control animals except for vanadium in the rockfish. Petroleum hydrocarbon fractions in sediments were generaly high relative to areas with no natural oil seeps, however the hydrocarbons measured were identified as highly weathered natual seep oil indicating no recent contamination. There also were slight elevations in sediment zinc and hydrocarbons below the towers.

No adverse effects on the fauna were observed; the high abundance of fish and the huge mussels suggest that the platforms are beneficial."