CHAPTER 3: SCIENTIFIC SUMMARY AND GENERAL DISCUSSION 



(Olle Linden, Ragnar Elmgren, Lars Westin and John Kineman) 



3.1 Background 



Few field studies of oil spills in the Baltic Sea are available. 

 The Palva accident in 1969 was the object of a study at Abo University 

 (Pelkonen and Tulkki, 1972). One year after the spill, no observable 

 damage was found in the coastal zone, but it should be noted that the 

 accident occurred at the very end of the archipelago of Finland's south- 

 western coast, a highly exposed area. 



The only previous study of the long-term effects of an oil spill in 

 the area exposed to Tsesis oil (Notini, 1977) has been a 5-year study of 

 the recovery following a spill at Gastviken, Musko. The bay was severely 

 contaminated with 400 tons of medium and heavy heating oil from the 

 grounded Irini in the month of October 1970. A widespread recoloni- 

 zation of the littoral fauna occurred quickly in the first summer after 

 the oil spill. The less rapidly moving organisms, such as mussels and 

 snails, reestablished themselves during the following years. Four years 

 after the oil spill, no effects could be discerned in the ecological 

 system of the Fucus belt zone in the bay, but the oil which was incor- 

 porated into the sediments of the bottom remained and was not signifi- 

 cantly degraded. The oil that remained on the beaches had been dras- 

 tically altered. The rapid recuperation of the bay is explained in part 

 by the large effort made to remove the oil by mechanical means, by the 

 small size of the bay, by the good water exchange properties, and by the 

 closeness of undisturbed areas which could serve as sources for recoloni- 

 zation . 



The studies mentioned above appear to illustrate the importance of 

 the relationship between energy in the system, oil degradation, and 

 ecological recovery. This relationship has been described convincingly 

 by several authors, including E.H. Owens (1978) and E. Gundlach et al. 

 (1978). Quantitatively, the largest oil catastrophes have all occurred 

 in areas of high energy, for instance, Metula 1974 (Straughan, 1977), 

 Santa Barbara 1969 (Straughan, 1971), Torrey Canyon 1967 (Southward and 



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