All of these physical, chemical, and biological processes act to keep the level of pe- 

 troleum low in the environment. It is fair to state that the> work effectively. Many 

 large oil spills are dispersed before they become a biological problem. For example, 

 the Argo Merchant spill off Cape Cod and the Ekofisk blow-out did not lead to 

 heavy accumulations. The massive l.xtoc 1 spill did lead to accumulations over a 

 960-km (600-mi) long track; however, foul weather and perhaps biological activity 

 finally removed most of the oil from the Texas coast. Nevertheless, the potential for 

 damage to marine plants and animals by chronic and acute inputs of petroleum is a 

 serious problem. Extensive studies have been done to help define and resolve this 

 problem. 



BIOLOGICAL EFFECTS 



The impact of petroleum on marine plants and animals is of central importance for 

 scientists and regulatory agencies concerned with the petroleum sector. This prob- 

 lem is a real challenge to scientists because it has many levels of expression, all of 

 which are important and perhaps interrelated. Determination of the acute toxicity of 

 petroleum and petroleum products toward marine plants and animals is complicated 

 by the fact that the sensitivity of various marine organisms is highly variable. Gener- 

 alizations are difficult to make. It is somewhat the case that levels of petroleum in the 

 environment high enough to cause acute toxicity are also high enough to trigger 

 cleanup efforts. As a consequence, much of the research on the biological effects of 

 oil during the past decade has been on the sublethal effects of oil. When one considers 

 that a given petroleum may contain more than 300 compounds, many of which may 

 be deleterious to some biota, the magnitude of the problem is clear. 



Research programs dealing with the harmful effects of petroleum form a matrix. 

 One side of the matrix is the level of organization of the biota. This ranges from im- 

 pact on key metabolic reactions such as photosynthesis and nitrogen fixation to ef- 

 fects on bacteria, phytoplankton, microzooplankton, zooplankton, larval animals, 

 invertebrates and large fish and finally to whole communities or ecosystems. The 

 other side of the matrix is individual petroleum compounds, various fuel oils 

 produced by the petroleum industry, and crude oils. The scientific community is 

 divided as to which matrix members are environmentally most critical. Some argue 

 to focus on the effects of oil on key processes such as photosynthesis or respiration, 

 others point to the need to understand the impact on commercial fish and shellfish, 

 while others contend that only the total ecosystem should be studied. The variety of 

 life and the chemically complex nature of petroleum determines that only limited 

 studies can be made of this matrix with the human and financial resources that are 

 available. Proceedings of the National Academy of Sciences workshop on marine 

 environmental quality provided useful guidelines for biological studies (National 

 Academy of Sciences, 1971). This document pointed out the inadequacy of acute 

 toxicity tests. It stated that the greatest scientific benefit would accrue if "intensive 

 research is focused on relatively few kinds of organisms and systems." Suggested 

 criteria for system selection include available basic data, economic importance, 

 magnitude, and exemplary nature. The decade of the 1970s has brought forth studies 

 along these lines ranging from microbes to ecosystems. 



How toxic is petroleum to marine organisms? The answer to this question is vital 

 to an assessment of environmental damage associated with specific petroleum pollu- 

 tion incidents that occur on a daily basis in the coastal zone. The answer is also vital 

 to assessment of the hazards of long-term chronic pollution of harbors, bays, and 

 estuaries. Biological effects observed when experimental organisms are exposed to 

 water-soluble fractions of oil, oil dispersed in seawater (accommodated oil), or spe- 

 cific petroleum components have received detailed study. Mortality of birds and 

 intertidal animals as a direct result of oil coating may be described as a form of acute 

 toxicity but will not be discussed here. 



102 



