Artificial habitat in the marine environment.

Abstract

This paper discusses the results of scuba surveys conducted around four offshore oil facilities in southern California: Platforms Hilda and Hazel, the Richfield Oil Island, and the Texaco Platform all located in the Santa Barbara Channel and a platform off Seal Beach. Of these, most effort was put into surveying Platforms Hazel and the oil island. Overall, the structures were surveyed by scuba from 1958 to 1960. Surfpeches (family Embiotocidae) and rockfishes (family Scorpaenidae) dominated the fish assemblages.

From the Conclusions: “Four offshore oil drilling installations near Santa Barbara and one near Seal Beach were visited between May 1958 and December 1960. A total of 246 man-hours was spent underwater around these rigs in 62 days of diving. The Monterey oil platform, Texaco tower and Standard-Humble tower Hilda accounted for only 9 of these 62 days. The routine monthly surveys of the Standard-Humble tower Hazel and Richfield's Rincon oil island required 27 days and 26 days respectively. These drilling sites exhibited similar attractions for fishes. Their respective populations grew from a few scattered fishes to several thousand semi-residents. The deeper water towers attracted pelagic schooling fishes and several species of rockfish that were not associated with the inshore areas. Typical of inshore areas were kelpfishes, croakers, and small sharks. In both areas embiotocid perch were the dominant fishes.

The fish populations increased rapidly for the first year and then exhibited fluctuations apparently correlated to temperature, season, or other natural factors. Encrusting organisms rapidly covered all exposed underwater areas and by December 1960 attachment space was at a premium. These organisms either fed the fishes or sheltered forms that did.

With regard to the two questions this investigation set out to answer, we can state that (i) the changes in habitat brought about by establishing offshore oil-drilling installations were generally beneficial to the flora and fauna, and (ii) depositing washed drill cuttings on the bottom at these sites was neither deleterious nor beneficial to the marine life in the area.

We do feel that if these cuttings were dumped several hundred feet away and capped with stones or other rubble to make suitable habitat, the result would be to establish a spot where anglers could fish without danger from falling objects or being in the way of vessels servicing the rigs.

Eighty-six species of fish were observed on all installations, as well as 142 kinds of invertebrates and 14 species of plants during 132 dives.”