productivity, system metabolism and structure, and species diversity. 

 Non-lethal incorporation of hydrocarbons in organisms is of interest 

 because of potential accumulation of aromatic hydrocarbons, especi- 

 ally carcinogens, in various marine organisms, and because of taint- 

 ing (developing an objectionable taste) of edible organisms with 

 hydrocarbons. 



The biological effects of oil spills are determined by the following 

 factors [5]: 



Type of oil spilled, in particular, the concentration of lower- 

 boiling aromatic hydrocarbons 

 Amount of oil 



Physiography of the spill area 

 Weather conditions at the time 

 Biota in the area 

 Season of the year 

 Previous exposure of the area to oil 

 Exposure to other pollutants 

 Method of treatment of the spill. 



Oil on Shore : When an oil slick reaches the shore, its behavior 

 depends on the nature of the oil, its emulsions, and the shore. Usually, 

 much of the oil will be carried to the beach along the high-water mark 

 by successive tides. Well -weathered or heavy oils mixed with sand or 

 plant debris during this process form oil-cakes that sink into sand 

 and gravel or cling to seaweeds. 



Pebble beaches are troublesome to clean, because the oil may sink 

 among the pebbles to a depth of several inches. Oil does not sink so 

 readily into wet sand. Breakers may, however, throw fresh sand over the 

 oil-containing sand, burying it. In this way a beach may appear clean 

 shortly after an oil slick has come ashore. Later removal of surface 

 layers during storms or in seasonal sand-movements exposes the oil. 



Oil may also persist on dry rock surfaces or among weeds, barnacles 

 and mussels, where it slowly erodes or flakes off because of drying and 

 hardening, or because it incorporates with sand particles. Oils cling to 

 the byssus-threads of mussels and to the outer layer of shells and cer- 

 tain upper-shore weeds, which have a naturally oil surface. Oil also 

 contaminates some marine grasses and flowering plants. 



Toxic Effects : Sensitivities of phytoplankton to petroleum vary 

 over a wide range. Kelp and other large marine plants are apparently 

 reasonably resistant perhaps due to coatings of mucous substances on the 

 stems and fronds of the plant. Long-term impacts of spilled oils on 



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