Chapter 8 Ecology of a Submarine Petroleum Seep off the California Coast

Abstract

This chapter integrates several current concepts of the ecology of a petroleum seep. Natural seepage is estimated to contribute 10% of the total hydrocarbons entering the oceans annually. Most seeps are small and intermittent and perhaps many emit only gas, but seeps around Coal Oil Point in the Santa Barbara Channel. In the shallow areas around Coal Oil Point, the bottom consists mainly of shale outcrops with rubble and sand. Between these areas are larger regions of less active but observable seepage. Gas bubbles are very common and are often associated with the oil droplets; there appears to be more gas seepage in those areas where oil seepage is most intense. Methane is the predominant gas. Large population pulses from the influx and growth of young infauna account for the lower stability measured at the seep, especially the variance/mean ratio of density. Heterotrophic enrichment, alteration of the sulfur cycle in sediments, and enhanced colonization of oiled sediments are features of the seep area that may be widely applicable to marine oil pollution.