every other day. Mussels were fed as described above. One-half volume (approximately 9 L) of 

 aquarium water was replaced with fresh, 20°C, filtered creek water every other day. Mussels 

 were allowed to remain at 20°C for a minimum of two days before testing. 

 2.3 Toxicity Assays for Year 1 



2.3.1. Ceriodaphnia dubia Acute Toxicity Assays 



Fifteen milliliters of porewater solution were placed in 30-ml plastic cups. Neonates 

 were collected from the brood boards and placed in a glass beaker containing 100 ml of culture 

 water. A subsample often neonates was removed from the beaker and then placed in one of the 

 30-ml test cups. A new subsample of neonates was collected for each test cup. Death was 

 defined as the cessation of movement of appendages, a motionless organism at the bottom of the 

 cup, or as failure of an organism to move after gentle prodding. Cups were observed for 

 mortality at 24 h and 48 h, and dead organisms were removed. 



2.3.2. Ceriodaphnia dubia Survival / Reproduction Assays 



A modified C. dubia Survival and Reproduction Test Method (USEPA 1989) was used 

 to assess the chronic toxicity of remaining volumes (approximately 925 ml) of each porewater 

 after conducting the acute toxicity assays. Two to three days before the test, the test brood 

 boards consisting of 60 brood cups were set up with one egg-bearing female each. The day that 

 12 or more brood cups had eight or more young (< 24 h old), the test was started. 



Two control solutions were used in the chronic test. The first was titled ""control" and 

 consisted of hard standard reconstituted water. The second was titled "storage control" and 

 consisted of hard standard reconstituted water stored in the ice chests for the same duration as the 

 sediments. The purpose of the storage control was to assess for any possibile toxic plasticizers, 



10 



