PETROLEUM AND ANTHROPOGENIC INFLUENCE ON THE COMPOSITION OF SEDIMENTS FROM THE SOUTHERN CALIFORNIA BIGHT1

Biochemical effects of petroleum exposure in hornyhead turbot (Pleuronichthys verticalis) exposed to a gradient of sediments collected from a natural petroleum seep in CA, USA

Concentrations of serum/plasma estradiol, biliary fluorescent aromatic compounds (FACs), levels of hepatic CYP1A expression, and DNA damage were measured in sexually mature hornyhead turbot (Pleuronichthys verticalis) exposed in the laboratory for 7 days to a gradient of sediments collected from a natural petroleum seep in the Santa Barbara Channel. Coal oil point (COP) sediments were homogenized and divided into four treatments containing 0 (sediment from the Orange County Sanitation District's reference location), 33, 66, and 100% (COP) sediments. Sediment concentrations of 20 PAHs ranged from below the detection limit for the 0% COP sediment treatments to 105 microg/g in the 100% treatments with lower molecular weight compounds predominating. Concentrations of biliary FACs were not linear with COP treatment but levels of hepatic DNA damage increased linearly with increasing concentrations of high molecular weight PAHs. Hepatic CYP1A expression was elevated only in the 100% treatments. A reduction of plasma estradiol in male and female fish was observed in all COP exposures. These results demonstrate that acute sediment-only exposure of flatfish to naturally-derived PAHs elicits alterations in biochemical endpoints indicative of PAH bioavailability and adverse effects with different sensitivities.

Observations on the effects of natural oil seeps in the Coal Oil Point area

Available data from population, community, and ecosystem studies from an area of natural marine oil seepage, Coal Oil Point, California, are reviewed and a hypothesis presented to explain the information. This suggests a relation that exists through time and space. Exposure to a large volume of petroleum results initially in total or almost total destruction of all organisms, followed by a stimulatory period, followed by a gradual return to ‘normal’. The time taken for these cycles varies with species, and initial impact varies with the exposure to petroleum. The Coal Oil Point area is a mosaic of small units that are at different stages in this process owing to the patchy distribution of petroleum in space and time, patchiness of habitats, and patchiness of species distribution. This is a possible explanation for the apparent overall enrichment observed in some communities in the area.