COMPARISON OF HYDROCARBONS IN BENTHIC FISH FROM COAL OIL POINT AND TANNER BANK, CALIFORNIA

Abstract

ABSTRACT Hydrocarbons of rockfish (Sebastes sp.), sanddab (Citharichthys sp.), and sole (Lyopsetta sp.) were analyzed by high resolution glass-capillary gas chromatography, following saponification in methanolic-KOH, extraction by n-hexane, and separation via liquid chromatography. The fish contained a wide range of hydrocarbons, with total concentrations varying from less than 10 µg/g dry weight to values exceeding 100 µg/g DW. Some differences between species were noted: levels of biogenic constituents decreased in the order—sanddab>rockfish>slender sole. Fish collected during the summer exhibited hydrocarbon profiles similar to those taken during winter. Gravid females were characterized by somewhat higher levels of hydrocarbons. Subtle differences were observed between fish collected near Coal Oil Point, a region of intense natural petroleum influx, and Tanner Bank, an area some 140 km offshore. Mean concentrations of hydrocarbons were elevated in COP fish (53.2 ± 38 µg/g), and many samples demonstrated characteristics of petroleum contamination. These characteristics were not accentuated in gravid females. Animals from Tanner Bank contained lesser amounts of hydrocarbons (x = 27.2 ± 15), with biogenic components often predominating over those of petroleum origin. Most fishes from both areas exhibited unresolved complex mixture (UCM) hydrocarbons. These data, in combination with the absence of petrogenic characteristics among resolvable hydrocarbons, suggest that samples were contaminated by low levels of weathered petroleum. The most abundant hydrocarbon was squalene, which was present in every sample. Synthetic chemicals such as p′, p′-DDE, poly chlorinated biphenyls, and plasticizers were present in nearly all fish samples, indicating the ubiquity of these compounds throughout the continental shelf biosphere. The relevance of these findings to marine pollution monitoring strategies is briefly discussed.