EVANS and RICE: EFFECTS OF OIL ON ECOSYSTEMS 



tially (Foster, Charters, and Neushul, 1971), yet 

 biological damage was not reported widespread 

 and the area has started to recover. Foster, 

 Neushul, and Zingmark (1971) observed that 

 much of the damage to intertidal areas corres- 

 ponded to sand movement, probably from storm 

 damage. Cimberg, Mann, and Straughan (1973) 

 concluded that the blowout had less effect on in- 

 tertidal marine organisms than did sand move- 

 ment and substrate stability. Straughan (1971), 

 reporting on investigations at Santa Barbara, 

 noted factors unique to that accident: 1) the long 

 history of natural oil seepage in the Santa Bar- 

 bara Channel and 2) the unusually heavy winter 

 runoff at the time of the spill, which reduced 

 salinities, increased sedimentation, and possibly 

 increased pesticides in the channel. R. L. Kolpack 

 (pers. commun. cited by Kanter, Straughan, and 

 Jessee (1971)) noted that Santa Barbara crude oil 

 is relatively insoluble in seawater and contains a 

 very low percentage of the toxic aromatic com- 

 pounds. Thus, information gathered on the effect 

 of the Santa Barbara spill or any other is of limited 

 utility in predicting the ecological effects of crude 

 oil spills or of other oils in other areas. 



Several studies have provided encouraging re- 

 ports of varying degrees of recovery after some of 

 the recent larger spills. Investigations about 11/2 

 yr after the Torrey Canyon spill revealed that at 

 least the affected shoreline areas were recoloniz- 

 ing and recovering, although recovery was not yet 

 complete at that time (Spooner, 1969). The areas 

 affected by the 1969 Santa Barbara blowout were 

 recently reported to be recovering (Cimberg et al., 

 1973), as was a reef affected by bunker C oil spilled 

 from a tanker collision in San Francisco Bay in 

 January 1971 (Chan, 1973). 



Too few of the controlled field investigations 

 have been designed to bridge the gap between field 

 surveys after spills and simulative laboratory ex- 

 periments. Perkins (1970) exposed periwinkles 

 and other intertidal organisms to the oil disper- 

 sant BP1002 in the laboratory and then released 

 marked individuals in the natural environment. 

 After recapture of the individuals exposed, he 

 found that survival from doses as low as one 

 three-thousandth of the 24 h LCso^ was lower 

 than among the recaptured controls. Crapp 

 (1971a) conducted field experiments by applying 

 crude oil and oil emulsifiers to the intertidal zone. 



^24 h LCso equals that dose of toxicant that resulted in 50% 

 survival after 24-h exposure. 



Physical damage by the oil was observed, but tox- 

 icity damage was not great because the oil had 

 previously been exposed to air; in contrast, the 

 oil-emulsifier mixtures were toxic. Baker (1970) 

 applied a crude oil to salt-marsh plots at different 

 times of the year and monitored the effects on 

 plants. Summer applications of oil severely af- 

 fected annuals but not perennials. 



Laboratory Studies 



Experiments in the laboratory also do not pro- 

 vide all the answers about how an oil spill will 

 affect a marine organism or its environment. 

 Laboratory research has demonstrated the toxic- 

 ity of various crude oils and petroleum products on 

 several forms of marine life. Much of this research 

 has focused on the planktonic life history stages of 

 pelagic and benthic animals. Many of these plank- 

 tonic larvae are phototactic at their earliest stages 

 and concentrate in the surface layer of the sea. 

 This community of the surface 5 cm, the neuston, 

 is the first affected by most oil entering the water. 

 Thus, many organisms are most sensitive to oil 

 pollution at the time of their greatest likelihood of 

 exposure. 



Studies by Mironov (1968) on the development 

 of fertilized eggs of the plaice. Rhombus 

 macoticus , showed extreme sensitivity of the eggs 

 to the influence of the oil products in seawater. He 

 noted that injury to the eggs occurred at concen- 

 trations of lO'^o lO'^ml/liter (0.1 to 0.01 ppm). In 

 these concentrations of oil products, 40 to 100% of 

 the hatched prelarvae showed some signs of de- 

 generation during development and perished. 

 Mironov (1969a) also demonstrated that 0.001 ml 

 of crude oil per liter was toxic to the eggs of an- 

 chovy, scorpionfish, and sea parrots from the 

 Black Sea. 



Newly set spat of Elinius modestus, an Aus- 

 tralian barnacle introduced to Europe, were tol- 

 erant of 100 ppm crude oil but showed reduced 

 cirral activity and retarded shell growth (Corner, 

 Southward, and Southward, 1968). Adults of this 

 species also showed reduced activity at 100 ppm 

 (Corner et al., 1968). 



Mironov (1969b) tested crude oil on several 

 copepods and a cladoceran, and found that 0.001 

 ml/liter accelerated death in all forms and that 

 0.1 ml/liter caused death in less than 1 day. Acar- 

 tia and Calanus died at 0.01 ml/liter oil in sea- 

 water in 72 to 96 h (Mironov, 1968). Larvae of 

 crab and shrimp died at 1 ppm (Mironov, 1969c). 



Little is known of the mechanisms of various 



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