porewaters are presented in Table 6. Although minimal acute mortality occurred, reproduction 

 by both control and treatment organisms was extremely low. Neither group of organisms 

 produced young until the seventh day of the test indicating poor health of the culture, and 

 invalidity of the test results. Therefore, no information concerning the toxicity of the sediments 

 of Pool 15 was gained from the C. dubia survival / reproduction assay during the second year of 

 the studv. 



Source 



No. of Adults % Mortality £ Young / 



Adult 



Sylvan Slough 

 Control 



9 1 1.55 



9 1 1.44 



Table 6. Results from C dubia survival / reproduction assay from the second year of the study. 

 Although adult mortality was minimal in both tests, the production of young by the adults was less than two young 

 per adult. The decreased reproduction by the adults indicated that the lab culture was in poor health. No conclusive 

 information regarding the toxicity of Svlvan Slouch sediments could be obtained from this test. 



3.2.2 Mussel Filtering Assay 



Mean filtering rates of T. truncata exposed to sediment porewaters and control solutions are 

 given in Table 7. One-way ANOVA indicated mussels exposed to Campbell's Slough 

 porewater exhibited significantly lower filtering rates compared to control mussels. Average 

 filtering rates in Sylvan Slough and ALCOA porewaters were not significantly different from 

 corresponding average control filtering rates. 



There was a 53% decline in filtering rates in mussels exposed to Campbell's Slough 

 porewaters and a 21% decline in filtering activity in those mussels exposed to Sylvan Slough 

 porewaters. Personnel detected an odor resembling petroleum from Campbell's Slough 



21 



