327 



Hydrocarbons are not foreign to the marine enx^ironment ; they are synthesized 

 by most, if not all, living organisms. Unicellular algae can produce normal 

 parafHn hydrocarbons from carbon dioxide, water and nutrients ; paraflBnic 

 hydrocarbons are found in most living organisms of the sea (Clark, 1966; Clark 

 and Blumer, 1967). 



There are certain characteristic differences, however, between biologically 

 produced hydrocarbons and pollution hydrocarbons, both in the distribution of 

 various hydrocarbon classes and in the molecular size of the hydrcarbons. Crude 

 oil and petroleum products are complex mixtures that contain molecules of 

 different sizes in a fairly even distribution whereas living organisms utilize 

 specific biosynthetic pathways that lead to specific hydrocarbon size groups 

 (Personal communication to D. R. Evans from R. C. Clark, Jr., 1971). 



Hydrocarbons are fat soluble and thus have the potential to be retained and 

 accumulated in organisms (Blumer, et al, 1970, p. 17). The major hydrocarbon 

 components in crude oil and in petroleum products can be classified with refer- 

 ence to known biological effects. These are summarized below. 



Low-boiling, saturated hydrocarbons are related to the fat-soluble anaesthetics 

 and have a narcotic effect on a wide variety of animals. In lower animals at low 

 concentrations they often cause sleep or reversible insensibility. At higher con- 

 centrations they often cause cell damage and death, especially in larval and 

 juvenile .stages of marine organisms. The solubility of these low-molecular-weight 

 hydrocarbons in water is of the order of 0.1 to 1.0 gram per liter (100 to 1,000 

 ppm), comparable to that of many drugs (Goldacre, 1968). 



Low-boiling aromatic hydrocarbons comprise the most toxic petroleum frac- 

 tions. The low-boiling aromatics are acutely poisonous to man and marine 

 o^gani^im alike. Benzene, toluene and phenols, such as found in crude oil, produce 

 in man reactions similar to tho.se of alcohol. The initial reaction is restlessness, 

 then excitement, inebriation, drowsiness, depression and sleep. Death may fol- 

 low from respiratory failure as the concentration rises (Goldacre, 1968). Chronic 

 exposure to low concentrations of some aromatics, especially benzene, may cause 

 bone marrow disease chromosome aberration and leukemia (Finkel, 1960). Low- 

 boiling aromatics, even more water-soluble than the saturates, can cause mor- 

 tality of marine organisms by contact, even with dilute solutions (Blumer, 1970, 

 p. 3). 



Olefinic hydrocarbons are not generally found in crude oils but are plentiful 

 in gasolines and other refined products. The fate of olefins in the marine environ- 

 ment is poorly understood, but this class of compounds is quite reactive and will 

 combine readily with hydrogen, oxygen, chlorine, sulfur and other elements to 

 produce toxic substances. Once incorporated into organisms, olefins remain 

 stable. The full range of olefinic hydrocarbons is reported as likely to interfere 

 with the reception of chemical messengers in the sea by marine organisms (Blu- 

 mer, 1970, p. 6). 



Higher-boiling, saturated hydrocarbons occur naturally in many organisms 

 and, while probably not toxic at low levels, they may interfere with chemo- 

 receptors, the communications system used by some organisms for locating food, 

 responding to sex attractants, and for identifying migration routes (Blumer. 

 1969, p. 7; 1970, p. 6). 



The higher-ceiling aromatics act as slower poisons than the lower-boiling 

 aromatic hydrocarbons, but they are equally severe in their effect ; in addition 

 some are known to cause cancer ! Benzpyrene, 1.2 benzanthracene and alkyl- 

 benzanthracenes have been isolated from crude oil and their carcinogenic effects 

 on animals and man demonstrated (Blumer, 1970, p. 4) . 



A study of the available information on potential effects of oil pollution reveals 

 more unknowns than proven conclusioos. It thus is not at all clear what the 

 acute and long-term effects of oil upon the environment and living marine re- 

 sources of a region would be. Early reviews of the effects of oil upon bacteria 

 and higher organisms (ZoBell, 1962, p. 85-117) reported no great impact of 

 oil upon fishery resources in general, but are inconclu.'->ive because they also reveal 

 incomplete general knowledge, particularly for north temperate, subarctic, and 

 arctic regions. Even fairly recent work, including several studies of the Torrey 

 Canyon, has depended upon on-site visual surveys after occurrence of the oil 

 spill (Nelson-Smith, 196S; Smith. 1968; Simjison, 1968), rather than experiments 

 and detailed study. These investigations have been limited mostly to effects of 

 oil and cleaning or dispersing agents upon primarily adult intertidal organisms 

 and populations. While these observations have contributed more understanding 



