Sediment Quality in Puget Sound Year 2 - Center for Coastal ...

hi central Puget Sound, the strata in which toxicity was highly significant (i.e., 4 0% of controls)
totaled about 0.7%, 0.2%, and 0.6% of the total area in tests of loo%, 50%, and 25% porewater
concentrations, respectively. These estimates are slightly lower than those calculated for the
northern Puget Sound area where the estimated areas were 5.2%, 1.5% and 0.8% of the total,
respectively.
NOAA estimated the spatial extent of toxicity in urchin fertilization or equivalent tests
performed with pore water in many other regions of the U. S. (Long et al., 1996). These
estimates ranged from 98% in San Pedro Bay (CA) to 0.0% in Leadenwah Creek (SC) (Table
37). As in the amphipod tests, northern Puget Sound ranked near the bottom of this range, well
below the "national average" of 25% calculated with data accumulated through 1997. Equivalent
results in this test were reported in areas such as St. Simons Sound (GA), St. Andrew Bay in
western Florida, and Leadenwah Creek (SC), in which urbanization and industrialization were
restricted to relatively small portions of the estuaries. Therefore, as with the amphipod tests,
these tests indicated that acute toxicity was neither widespread nor severe in sediments from the
northern and central Puget Sound study areas.
Microbial Bioluminescence (MicrotoxTM) - Organic Solvent Extract
The MicrotoxTM tests were performed with organic solvent extracts of the sediments. These
extracts were intended to elute all potentially toxic organic substances from the sediments
regardless of their bioavailability. The tests, therefore, provide an estimate of the potential for
toxicity attributable to complex mixtures of toxicants associated with the sediment particles,
which normally may not be available to benthic infauna. This test is not sensitive to the presence
of ammonia, hydrogen sulfide, fine-grained particles or other features of sediments that may
confound results of other tests. The test endpoint is a measure of metabolic activity, not acute
mortality. These features combined to provide a relatively sensitive test - usually the most
sensitive test performed nationwide in the NOAA surveys (Long et al., 1996).
In northern Puget Sound, the data were difficult to interpret because of the unusual result in the
negative control sample from Redfish Bay (TX). Test results for the control showed the sample
to be considerably less toxic relative to previous tests of sediments from that site and to tests of
negative control sediments from other sites used in previous surveys. Therefore, new analytical
tools weregenerated with the compiled NOAA data to provide a meaningful critical value for
evaluating the northern Puget Sound data (Long et al., 1999a).
Using a critical value of