animal to lose heat and eventually cause death by hypothermia or 

 by lowered resistance to disease. Caged sea otters inadvertently 

 contaminated with oil died within a few hours, apparently from 

 exposure [175]. 



In Gulf Coast marshes, fur-bearing mammals (muskrat, nutria, otter) 

 get oil in their coats which destroys their insulating qualities and may 

 impede swimming. During cold weather death usually results from over- 

 exposure and in summer overheating may occur. Marsh grasses usually 

 recover in 1 year, especially if the marsh is burned. Animals will re- 

 turn to the marsh when the spilled oil is no longer present [175]. 



Birds, being warm-blooded, must likewise insulate themselves against 

 heat loss; furthermore, their insulation must be waterproof. Some species 

 of oceanic birds rarely come into contact with oil, whether floating or 

 beached, and thus are not especially endangered. Swimming birds are 

 continually subject to contact with floating oil slicks. Often their 

 first reaction upon coming in contact with oil is to dive beneath it, 

 invariably resurfacing in the slick, compounding the problem. Oil causes 

 the insulating layer of feathers to mat, reducing or destroying their 

 insulating qualities and causing the bird to freeze or die of disease 

 caused by lowered body temperatures. The buoyancy maintained by the air- 

 filled feathers is also disturbed and the bird may drown. Feeding may 

 become difficult, because the bird may have difficulty moving and food 

 sources may also be contaminated by oil. Only limited success has been 

 achieved in cleaning oil from birds and releasing them; high mortalities 

 commonly occur although new techniques and materials are being developed 

 [173] [174]. 



Persistence : Once mixed in ocean waters, oil is usually absorbed 

 into the surfaces of suspended particles, eventually settling to the 

 bottom. The amount of oil absorbed by sediments is related to particle 

 surface area. In general, the smaller the sediment particles have a 

 larger total surface area. Thus, all other things being equal, there 

 will be more oil associated with clay sediments than with sands [173]. 



Once incorporated into sediments, oil generally degrades slowly. 

 At the sediment surface, aerobic (oxygen utilizing) bacteria can degrade 

 some fractions of the oil. Deeper in the sediment, there is usually no 

 oxygen and only anaerobic bacteria (which avoid free oxygen) can function. 

 Anaerobic degradation of oil is much slower than in aerobic conditions. 

 Oil in sediments frequently persists for months or years before it breaks 

 down, assuming no new oil is introduced. In the meantime, waves or 

 unusually strong currents can resuspend the oil so that it can be moved 

 into other areas. (Some possible synergistic effects were discussed in 

 a previous section.) 



Sediment particle sizes also play a major role in determining 

 which organisms live in the sediments. Detritus feeders such as many 



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