INTRODUCTION The Santa Barbara Channel@ and to a certain extent@ other areas of the southern California Borderland@ provide a unique opportunity to study the long-term effects of chronic exposure of marine organisms to petroleum. This is not because the human race has been more careless in the handling of petroleum in this area than elsewhere@ but because this is an area where natural petroleum seepage occurs. Hence@ it provides a natural laboratory to study the long-term effects of chronic exposure to petroleum on marine organisms. The presence of these oil seeps is documented prior to the Spanish settlements in the 1780's and by Spanish explorers as early as 1543 [1]. Dibblee [2] reported that the early Chumash Indians of the Santa Ynez region used 'the asphalt material washed up on Coal Oil Point for water-proofing and mending their dug-out canoes. Emery [3] reviewed historical records of natural oil seepage but@ without evidence such as the skeletons of Pleistocene vertebrates that are found in the La Brea Tar Pits@ it was impossible to state how long these submarine oil seeps had been active. However@ Emery [3] presented data which showed the presence of petroleum compounds to depths of over 400 cm in the Santa Barbara Basin. Recently@ several studies mapped many of the oil and gas seeps as well as old tar mounds in the Santa Barbara Channel [4]. Much of this work was associated with oil exploration. Further work determined seepage rates [5@6@7] and observed the type of petroleum emissions and formations on the ocean floor [8@9@10@11]. However@ all of this work is frustrated by the intermittent nature of this seepage and the variability in type of emission. The variability in the seepage rates was dramatically illustrated in June 1973@ when a 'new oil spill' was reported in the Santa Barbara Channel. Investigations showed this to be an increase in oil seepage in an area at Coal Oil Point [10]. The reasons for this increase in oil seepage are still unknown.