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.