EVANS and RICE: EFFECTS OF OIL ON ECOSYSTEMS 



Mytilus edulis. was noted by Lee, Sauerheber, and 

 Benson ( 1972 ). Smith ( 1968) reported the presence 

 of oil and benzene-ring compounds in the feces of 

 limpets browsing on an oily deposit, and in top 

 shells, Monodonta, and limpets, Pa te//a, living on 

 oiled rocks. He reported that analysis of the gut 

 indicated "the proportion of oil in material in- 

 gested by these animals was estimated as about 

 20-30 percent in Patella and 5-50 percent in 

 Monodonta ." 



Organisms at the highest trophic levels may be 

 affected directly by the oil itself or indirectly by 

 hydrocarbons that have reached them through the 

 food web. Horn, Teal, and Backus (1970) found 

 large amounts of tar in the stomachs of three 

 saury, Scomberesox saurus, from a sample often 

 in the Mediterranean Sea near Gibraltar. Al- 

 though saury are generally considered to be car- 

 nivorous, the occurrence of tar and also of "vege- 

 table debris" in one of the stomachs examined by 

 Horn et al. ( 1970) suggests that the species is not a 

 vei-y discriminate feeder. Although all ingested oil 

 was obviously not incorporated into the tissues 

 (some oil was found in feces), such feeding be- 

 havior does describe a pathway for hydrocarbons 

 to be directly taken up into the tissues of the or- 

 ganism. Thus, oil ingested, absorbed, and even 

 adsorbed may enter the food chain when contami- 

 nated organisms are eaten. 



Carcinogenicity 



Some doubt may remain as to the direct car- 

 cinogenicity to man of crude oil and crude oil res- 

 idues in marine organisms (Blumer, 1969), but 

 evidence pointing toward this is accumulating 

 (Blumer, 1970, see footnote 3; 1972). A literature 

 search and evaluation conducted for the U.S. 

 Coast Guard by Battelle Memorial Institute 

 (1967) noted that shellfish, although alive, may 

 have been unfit for consumption because of the 

 carcinogenic hydrocarbon 3, 4-benzpyrene in their 

 bodies. Oysters that were heavily polluted and 

 contaminated with ship fuel oil were reported to 

 contain 3, 4-benzpyrene. The Battelle review also 

 reported that barnacles attached to creosoted 

 poles contained the same carcinogenic hydrocar- 

 bon (3, 4-benzpyrene). Sarcomas were elicited 

 when extracts from the barnacles were injected 

 into mice. The endem.ic occurrence of papillary 

 tumors around the rectal opening of soft-shell 

 clam, Mya arenario , was reported, but the author 

 (Battelle Memorial Institute, 1967) did not feel 



these were due to oil pollution, even though the 

 clams were taken from waters adjacent to areas 

 highly polluted by ship fuel oil. Hyperplasia in 

 reproductive cells of a bryozoan in response to coal 

 tar derivatives was observed by Powell, Sayce, 

 and Tufts (1970). They noted that similar abnor- 

 malities may also have occurred in coastal faunas 

 exposed to spills such as the Torrey Canyon and 

 the Santa Barbara blowout. However, most obser- 

 vations on these spills were concerned with gross 

 mortality and may not have detected the sublethal 

 effects. 



ZoBell (1971) reported the natural synthesis 

 and metabolism of carcinogenic hydrocarbons by 

 several marine organisms. Thus, oil pollution is 

 certainly not the only source for carcinogenic hy- 

 drocarbon introduction into marine food webs. 

 Suess (1972) recognized that carcinogens were in 

 seafoods but concluded that they would probably 

 not be dangerous unless the foods contained an 

 excess amount of polynuclear aromatic hydrocar- 

 bon carcinogens. Carcinogenesis from oil- 

 contaminated marine organisms has not been 

 proved, but Ehrhardt (1972) expressed a need for 

 carcinogenic testing of hydrocarbon fractions ex- 

 tracted from marine organisms contaminated by 

 exposure to oil. 



Observed Toxic Effects 



A study of the available information on poten- 

 tial toxic effects of oil pollution reveals more un- 

 knowns than proven conclusions. Only a decade 

 ago, ZoBell ( 1963) reviewed the literature on the 

 effects of oil on bacteria and higher organisms and 

 concluded that oil pollution had no great adverse 

 impact on fishery resources in general. He did 

 point out, however, a few reports of toxic effects, 

 tainting of flesh, and damage to vessels and 

 fishing gear. 



The quantity of literature on effects of oil spills 

 has increased since the Torrey Canyon incident of 

 1967. Most of the recent work has depended on 

 onsite visual surveys after occurrence of an oil 

 spill rather than on experiments and detailed 

 study. The surveys have been limited mostly to 

 the effects of oil and of cleaning or dispersing 

 agents on primarily adult intertidal organisms 

 and populations. These observations on a restrict- 

 ed segment of the affected ecosystem include only a 

 few of the factors that influence the total impact of 

 oil. Wilson, Cowell, and Beynon (1973) noted that 

 the absence of results from studies at the commu- 



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