sediments, indicating a possible source of toxicity. Mussels exposed to porewater collected 

 from ALCOA sediments displayed a small, insignificant increase in filtering activity (1%) (Table 

 7). 



Table 7. Mean filtering rates (mg yeast • g dry wt mussel' 1 - h" 1 ) for mussels exposed to Sylvan Slough, Campbell's 

 Slough and ALCOA site porewaters. 



Filtering rates of mussels exposed to Sylvan Slough and ALCOA sediment porewaters were not significantly 

 different (indicated by n.s.) from those mussels exposed to the control solution (filtered creek water). Mussels 

 exposed to Campbell's Slough sediment porewaters exhibited significantly lower (indicated by **, p < 0.05) 

 filtering rates compared to mussels exposed to the control solution. 



22 



