The Washington Department of Ecology annually determines the quality of recently deposited sediments in Puget Sound as a part of Ecology's Urban Waters Initiative. The annual sediment quality studies use the Sediment Quality Triad (SQT) approach, thus relying on measures of chemical contamination, toxicity, and benthic in-faunal effects (Chapman, 1990). Since 2002, the studies followed a rotating sampling scheme, each year sampling a different region of the greater Puget Sound Basin. During the annual studies, samples are collected in locations selected with a stratified-random design, patterned after the designs previously used in baseline surveys completed during 1997-1999 (Long and others, 2003; Wilson and Partridge, 2007).
Sediment samples were collected by personnel from the Washington Department of Ecology, in June of 2010 and shipped to the U. S. Geological Survey (USGS) laboratory in Corpus Christi, Texas (not shown), where the tests were performed. Sediment pore water was extracted with a pneumatic apparatus and was stored frozen. Just before testing, water-quality measurements were made and salinity adjusted, if necessary. Tests were performed on a dilution series of each sample consisting of 100-, 50-, and 25-percent pore-water concentrations.
The specific objectives of this study were to:
* Extract sediment pore water from a total of 30 sediment samples from the Bellingham Bay, Washington area within a day of receipt of the samples.
* Measure water-quality parameters (salinity, dissolved oxygen, pH, sulfide, and ammonia) of thawed pore-water samples before testing and adjust salinity, temperature and dissolved oxygen, if necessary, to obtain optimal ranges for the test species.
* Conduct the fertilization toxicity test with pore water using sea urchin (Stronylocentrotus purpuratus) (S. purpuratus) gametes.
* Perform quality control assays with reference pore water, dilution blanks and a positive control dilution series with sodium dodecyl sulfate (SDS) in conjunction with each test.
* Determine which samples caused a significant decrease in percent fertilization success relative to the negative control.