CHAPTER 6: IMPACT OF OIL ON DEEP SOFT BOTTOMS 



(Ragnar Elmgren, Sture Hansson, Ulf Larsson and Brita Sundelin) 



6. 1 Introduction 



6.1.1 Background 



Since the Torrey Canyon catastrophe in 1967, millions of dollars 

 have been invested in research on the biological effects of oil pollu- 

 tion of the seas. Innumerable scientific papers, summarized in many 

 books and reviews (e.g. GESAMP 1977, Mclntyre and Whittle 1977, Cowell 

 1977), have resulted. Most of these studies have, however, been con- 

 cerned either with the surface layer of the sea, where plankton, fish 

 and fish eggs as well as sea birds may be affected by a spill, or with 

 the intertidal zone, where stranded oil may cause extensive destruction 

 of the natural communities . Relatively little attention has been given 

 to the effects of oil on subtidal benthos communities, even if a few 

 good field studies exist (e.g., Addy et al., 1979; the West Falmouth oil 

 spill study, Sanders, 1978). These few studies are all, however, 

 concerned only with the benthic macrofauna, while the smaller meiofauna 

 is totally ignored, even though its importance in energy flow terms is 

 often similar to that of the macrofauna. 



This general picture is also valid for the Baltic Sea. Furthermore 

 the Baltic ecosystem has so many unique features, that the usefulness of 

 studies from tidal and more fully marine areas for risk evaluation 

 concerning various types of pollutants in the Baltic is questionable. 

 Almost the only study of oil impact on a Baltic soft bottom community is 

 that by Leppakoski and Lindstrom (1978), and treats continuous oil 

 pollution from a refinery, rather than an acute spill situation. The 

 small study of the Palva spill by Mustonen and Tulkki (1972) should 

 perhaps also be mentioned, even though it is rather inconclusive. 



This comparative dearth of information is the more unfortunate, as 

 studies from the intertidal zone show that recovery from an oil spill is 

 slowest in fine sediment environments, where oil may persist virtually 



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