Figure 9-6. Oil Spill: Comparison of Filtering Activity 
of Mytilus edulis Collected From a Clean Area and from an 
Area Impacted by an Accidental Spill of No. 6 Fuel Oil. 
week after the spill, another collection was made. Test results indicated that 
feeding activity of the oiled mussels had improved to the point that no 
differences could be found between control and oiled groups. 
In conclusion, the investigation demonstrates that (1) under laboratory 
conditions an adverse reduction in filtration rate occurs in Mytilus edulis at 
very low levels of continuous oil exposure; (2) the effect is reversible, since 
recovery will gradually occur if the stressed animals are returned to unpolluted 
conditions; and (3) a similar effect occurs in response to spilled oil in the 
natural environment. 
ACKNOWLEDGEMENTS 
Grateful appreciation is extended to Ms. Terry Richie and Dr. James Heltshe 
for their assistance with the statistical analyses. 
REFERENCES 
l.Abel, P.D. 1976. Effects of Some Pollutants on the Filtration Rate of 
Mytilus. Mar. Pollut. Bull. 7(12): 228-231. 
120 
