Aleutian Islands), which leads to stagnation and oxygen deficiency at 

 depths below 60-70 m and a consequent severe reduction of the bottom 

 fauna below this zone. The area exposed to Tsesis oil did not include 

 depths below 60 in, however. 



The ecological importance of the above differences cannot be com- 

 pletely evaluated at present, due to lack of experimental data; however, 

 as in the case of studies in controlled ecosystems, some differences may 

 be desirable for the conduct of specific studies. A comparison of 

 significant stresses (Table 2.2.2), for example, suggests that some 

 stresses commonly imposed on marine communities and organisms in Alaska, 

 are either negligible or held constant in the Baltic. This implies a 

 more "controlled" situation in the Baltic and may help to isolate the 

 effects of the spill from other perturbations. On the other hand, as 

 shown in Table 2.2.3, the major differences combine to suggest a longer 

 retention time and slower degradation of oil at the Tsesis site than at 

 most places in Alaska. 



Although there are important differences in physical conditions 

 between the Baltic and Alaskan coastal waters, the similarities 

 mentioned initially still indicate that oil pollution studies in the two 

 areas have important problems of common interest, such as: 



1. Oil degradation in waters of very low temperature, especially 

 studies of oil degradation in deeper (below 20 m) Baltic soft 

 bottoms; these should he highly relevant for Alaskan environ- 

 mental impact studies. 



2. Community level effects in the deep soft bottoms. 



3. Vulnerability of shared species (Table 2.2.1), some of which 

 have been shown to be exceptionally susceptible to oil 

 pollution, e.g., Pontoporeia femorata (Rohrbacher-Carls , 

 1978). 



A. Problems connected with oil spills in ice-covered areas. 



5. Problems connected with oil spills in osmotically stressed 

 environments . 



6. Problems connected with oil spills in environments with a high 

 number of islands (fjords, bays, etc.) that create long coast- 

 lines in a small area. 



36 



